Zinc

What is zinc and what does it do?

Zinc is a nutrient that people need to stay healthy. Zinc is found in cells throughout the body. It helps the immune system fight off invading bacteria and viruses. The body also needs zinc to make proteins and DNA, the geneticmaterial in all cells. During pregnancy, infancy, and childhood, the body needs zinc to grow and develop properly. Zinc also helps wounds heal and is important for proper senses of taste and smell.

How much zinc do I need?

The amount of zinc you need each day depends on your age. Average daily recommended amounts for different ages are listed below in milligrams (mg):

Life Stage Recommended Amount
Birth to 6 months 2 mg
Infants 7–12 months 3 mg
Children 1–3 years 3 mg
Children 4–8 years 5 mg
Children 9–13 years 8 mg
Teens 14–18 years (boys) 11 mg
Teens 14–18 years (girls) 9 mg
Adults (men) 11 mg
Adults (women) 8 mg
Pregnant teens 12 mg
Pregnant women 11 mg
Breastfeeding teens 13 mg
Breastfeeding women 12 mg

What foods provide zinc?

Zinc is found in a wide variety of foods. You can get recommended amounts of zinc by eating a variety of foods including the following:

  • Oysters, which are the best source of zinc.
  • Red meat, poultry, seafood such as crab and lobsters, and fortified food products
  • Beans, nuts, whole grains, and dairy products, which provide some zinc.

What kinds of zinc dietary supplements are available?

Zinc is present in almost all multivitamin/mineral dietary supplements. It is also available alone or combined with calcium, magnesium or other ingredients in dietary supplements. Dietary supplements can have several different forms of zinc including zinc gluconate, zinc sulfate and zinc acetate. It is not clear whether one form is better than the others.

Zinc is also present in some denture adhesive creams. Using large amounts of these products, well beyond recommended levels, could lead to excessive zinc intake and copper deficiency. This can cause neurological problems, including numbness and weakness in the arms and legs.

Am I getting enough zinc?

Most people in the Western world get enough zinc from the foods they eat.

However, certain groups of people are more likely than others to have trouble getting enough zinc:

  • People who have had gastrointestinal surgery, such as weight loss surgery, or who have digestive disorders, such as ulcerative colitis or Crohn’s disease. These conditions can both decrease the amount of zinc that the body absorbs and increase the amount lost in the urine.
  • Vegetarians because they do not eat meat, which is a good source of zinc. Also, the beans and grains they typically eat have compounds that keep zinc from being fully absorbed by the body. For this reason, vegetarians might need to eat as much as 50% more zinc than the recommended amounts.
  • Older infants who are breastfed because breast milk does not have enough zinc for infants over 6 months of age. Older infants who do not take formula should be given foods that have zinc such as pureed meats. Formula-fed infants get enough zinc from infant formula.
  • Alcoholics because alcoholic beverages decrease the amount of zinc that the body absorbs and increase the amount lost in the urine. Also, many alcoholics eat a limited amount and variety of food, so they may not get enough zinc.
  • People with sickle cell disease because they might need more zinc.

What happens if I don’t get enough zinc?

Zinc deficiency is rare in North America. It causes slow growth in infants and children, delayed sexual development in adolescents and impotence in men. Zinc deficiency also causes hair loss, diarrhea, eye and skin sores and loss of appetite. Weight loss, problems with wound healing, decreased ability to taste food, and lower alertness levels can also occur.

Many of these symptoms can be signs of problems other than zinc deficiency. If you have these symptoms, your doctor can help determine whether you might have a zinc deficiency.

What are some effects of zinc on health?

Scientists are studying zinc to learn about its effects on the immune system (the body’s defense system against bacteria, viruses, and other foreign invaders). Scientists are also researching possible connections between zinc and the health problems discussed below.

Immune system and wound healing

The body’s immune system needs zinc to do its job. Older people and children in developing countries who have low levels of zinc might have a higher risk of getting pneumonia and other infections. Zinc also helps the skin stay healthy. Some people who have skin ulcers might benefit from zinc dietary supplements, but only if they have low levels of zinc.

Diarrhea

Children in developing countries often die from diarrhea. Studies show that zinc dietary supplements help reduce the symptoms and duration of diarrhea in these children, many of whom are zinc deficient or otherwise malnourished. The World Health Organization and UNICEF recommend that children with diarrhea take zinc for 10–14 days (20 mg/day, or 10 mg/day for infants under 6 months). It is not clear whether zinc dietary supplements can help treatdiarrhea in children who get enough zinc, such as most children in the United States.

The common cold

Some studies suggest that zinc lozenges or syrup (but not zinc dietary supplements in pill form) help speed recovery from the common cold and reduce its symptoms if taken within 24 hours of coming down with a cold. However, more study is needed to determine the best dose and form of zinc, as well as how long it should be taken before zinc can be recommended as a treatment for the common cold.

Age-related macular degeneration (AMD)

AMD is an eye disease that gradually causes vision loss. Research suggests that zinc might help keep early AMD from worsening into advanced AMD. In a large study, older people with AMD who took a daily dietary supplement with 80 mg zinc, 500 mg vitamin C, 400 IU vitamin E, 15 mg beta-carotene, and 2 mg copper for about 6 years had a lower chance of developing advanced AMD and less vision loss than those who did not take the dietary supplement. In the same study, people at high risk of the disease who took dietary supplements containing only zinc also had a lower risk of getting advanced AMD than those who did not take zinc dietary supplements. More research is needed before doctors can recommend zinc dietary supplements for patients with AMD. However, people who have or are developing the disease might want to talk with their doctor about taking dietary supplements.

Can zinc be harmful?

Yes, if you get too much. Signs of too much zinc include nausea, vomiting, loss of appetite, stomach cramps, diarrhea, and headaches. When people take too much zinc for a long time, they sometimes have problems such as low copper levels, lower immunity, and low levels of HDL cholesterol (the “good” cholesterol).

The safe upper limits for zinc are listed below. These levels do not apply to people who are taking zinc for medical reasons under the care of a doctor:

Life Stage Upper Safe Limit
Birth to 6 months 4 mg
Infants 7–12 months 5 mg
Children 1–3 years 7 mg
Children 4–8 years 12 mg
Children 9–13 years 23 mg
Teens 14–18 years 34 mg
Adults 40 mg

 Are there any interactions with zinc that I should know about?

Yes. Zinc dietary supplements can interact or interfere with medicines that you take and, in some cases, medicines can lower zinc levels in the body. Here are several examples:

  • Taking a zinc dietary supplement along with quinolone or tetracycline antibiotics (such as Cipro®,Achromycin®, and Sumycin®) reduces the amount of both zinc and the antibiotic that the body absorbs. Taking the antibiotic at least 2 hours before or 4–6 hours after taking a zinc dietary supplement helps minimize this effect.
  • Zinc dietary supplements can reduce the amount of penicillamine (a drug used to treat rheumatoid arthritis) that the body absorbs. They also make penicillamine work less well. Taking zinc dietary supplements at least 2 hours before or after taking penicillamine helps minimize this effect.
  • Thiazide diuretics, such as chlorthalidone (brand name Hygroton®) and hydrochlorothiazide (brand namesEsidrix® and HydroDIURIL®) increase the amount of zinc lost in the urine. Taking thiazide diuretics for a long time could decrease the amount of zinc in the body.

Resources

http://ods.od.nih.gov/factsheets/Zinc-QuickFacts/

oysters

Omega 3 & Omega 6

What is Omega-3 and Omega-6 fatty acids & their known functions?

There are two major classes of polyunsaturated fatty acids (PUFAs): the omega-3 and the omega-6 fatty acids. They are distinguished by their chemical structure. Only the fatty acids alpha-linolenic acid (ALA) and linoleic acid (LA) must come from the diet because they cannot be made by the body. ALA, an omega-3 fatty acid, is converted in the body to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA also occur naturally in some foods. LA, an omega-6 fatty acid, is converted in the body to arachidonic acid (AA). Both EPA and DHA are metabolized through the same biochemical pathways as AA. Studies show that omega-3 fatty acids in general decrease triglyceride and very-low-density lipoprotein blood levels in hyperlipidemic individuals but may increase or have no effect on low-density lipoprotein (LDL) levels.

Both AA and EPA are further metabolized to produce hormone-like agents called eicosanoids, which include prostaglandins, thromboxanes, and leukotrienes. Eicosanoids regulate fundamental physiological processes such as cell division and growth, blood clotting, muscle activity, secretion of digestive juices and hormones, and movement of substances like calcium into and out of cells. However, AA and EPA lead to the production of different subgroups of eicosanoids with sometimes opposing effects. Eicosanoids formed from AA (particularly the series-2 prostaglandins and series-4 leukotrienes) are released in the body in response to injury, infection, stress, or certain diseases. They increase platelet aggregation and enhance vasoconstriction and the synthesis of substances involved with the inflammatory process. Eicosanoids derived from EPA (particularly the series-3 prostaglandins), in contrast, decrease excessive series-2 prostaglandin production. As a result, adequate production of EPA-derived series-3 prostaglandins may help protect individuals against heart attacks and strokes as well as certain inflammatory diseases such as arthritis, systemic lupus erythematosus, and asthma.

The omega-3 fatty acid DHA, while not involved in eicosanoid formation, is the major polyunsaturated fatty acid found in the brain and is important for brain development and function. Synapses are rich in DHA, which suggests that this fatty acid is involved in signal transmission along neurons. DHA is also required to produce one member of a family of compounds called resolvins that participate in the body’s response to inflammation in the brain. The DHA-derived resolvin in particular helps to reduce inflammation brought about by ischemic insults (reductions in blood flow). (EPA also helps to temper inflammatory responses by decreasing production of proinflammatory compounds such as cytokines.)

Most Western diets provide at least 10 times more omega-6 than omega-3 fatty acids. There is now general scientific agreement that individuals should consume more omega-3 and fewer omega-6 fatty acids for good health. It is not known, however, whether a desirable ratio of omega-6 to omega-3 fatty acids exists for the diet or to what extent high intakes of omega-6 fatty acids interfere with any benefits of omega-3 fatty acid consumption.

What foods contains Omega 3 (ALA – alpha-linolenic acid)?

  • Leafy green vegetables
  • Nuts
  • Vegetable oils such as canola and soy, and especially in flaxseed and flaxseed oil.
  • Good sources of EPA and DHA are fish (both finfish and shellfish and their oils and eggs) and organ meats.

What foods contains Omega 6 (LA – linolenic acid)?

  • Meat
  • Vegetable oils (e.g., safflower, sunflower, corn, soy)
  • Processed foods made with these oils.

The Institute of Medicine has established Adequate Intakes for ALA and LA (1.1-1.6 g/day and 11-17 g/day, respectively, for adults) but not for EPA and DHA.

Products available

Omega-3 fatty acids are found in a variety of dietary supplements. For example, products containing flaxseed oil provide ALA, fish-oil supplements provide EPA and DHA, and algal oils provide a vegetarian source of DHA.

Omega-3 fatty acids for cardiovascular health and disease

Epidemiological studies first published in the late 1970s noted relatively low cardiovascular mortality in populations such as Eskimos with high fish consumption. The apparent health benefits of fish are explained, at least in part, by the EPA and DHA they contain.

The three reports by the Tufts EPC focused on different areas of research concerning this relationship between omega-3 fatty acids and cardiovascular health and disease and involved systematic reviews of the available scientific-medical literature.

Cardiovascular risk factors and intermediate markers of CVD

Overall, strong evidence showed that fish-oil supplements had a substantial and beneficial effect on triglycerides that was greater with larger intakes of fish oil; most studies reported a net decrease of about 10-33%. There is also evidence of a very small beneficial effect of fish oils on blood pressure and possible beneficial effects on coronary artery restenosis after angioplasty, exercise capacity in patients with coronary atherosclerosis, and heart rate variability (particularly in patients with recent myocardial infarctions).

Cardiovascular disease

Overall, evidence from both the primary and secondary prevention studies supports the hypothesis that consumption of omega-3 fatty acids, fish, and fish oil reduces all-cause mortality and various CVD outcomes such as sudden death, cardiac death, and myocardial infarction. The evidence is strongest for fish or fish oil whereas the potential effects of ALA are largely unknown and the relative effects of ALA versus fish oil are not well defined. In the only RCT that directly compared ALA and fish oil, both treatments reduced CVD outcome.

The lessons to be drawn from all these studies to date regarding use of omega-3 fatty acids for preventing and treating CVD are not completely clear. Because the studies involved a variety of methods of estimating fish or omega-3 fatty acid intake, background diets, background risk for heart disease, settings, and methods for reporting results, the validity of applying the results of studies conducted outside the United States to the U.S. population is uncertain. Furthermore, dietary intervention trials are limited by the multiple and complex dietary changes in the trials that make it difficult to distinguish among components and determine which specific components or combinations of these diets are most beneficial. For example, the different types of fish consumed and the method of food preparation may cause different effects.

Omega-3 fatty acids for asthma

Basic research suggests that omega-3 fatty acids may affect asthma because they influence substances that are part of the inflammatory process involved with asthma, such as the series-2 prostaglandin PGE2.

Whether omega-3 fatty acids are effective in the primary prevention of asthma is unknown. Four observational studies in children support a positive association for dietary patterns that include all fish or oily fish, but a prospective study of adult nurses found no association between asthma onset and dietary fish intake.

Omega-3 fatty acids for other diseases

The RAND EPC conducted a comprehensive search of published and unpublished scientific-medical literature on the health effects of omega-3 fatty acids in type II diabetes and metabolic syndrome, inflammatory bowel disease, rheumatoid arthritis, renal disease, systemic lupus erythematosus, and bone density/osteoporosis.

Type II diabetes and metabolic syndrome

Eighteen of the 34 RCTs whose subjects had type II diabetes or metabolic syndrome provided sufficient statistics to be included in a meta-analysis. The analysis found that omega-3 fatty acids had a favorable effect on triglyceride levels when compared with placebo but had no effect on total, LDL, or HDL cholesterol; fasting blood sugar; or glycosylated hemoglobin. A qualitative analysis of 4 studies concluded that omega-3 fatty acids had no effect on plasma insulin or insulin resistance in subjects with either disorder.

Inflammatory bowel disease (Crohn’s disease and ulcerative colitis)
In the 13 studies that reported outcomes in patients with inflammatory bowel disease, omega-3 fatty acids had variable effects on assessment scores (clinical, sigmoidoscopic, and histologic), induced remission, and relapse rates.

Rheumatoid arthritis

A meta-analysis of nine studies of patients with rheumatoid arthritis concluded that omega-3 fatty acids had no effect on patients’ reports of pain and disease severity, swollen joint count, or erythrocyte sedimentation rate (a measure of disease activity). However, an earlier meta-analysis found that the omega-3 fatty acids produced a statistically significant improvement in tender joint count as compared with placebo. A qualitative analysis of seven studies that assessed the effect of omega-3 fatty acids on anti-inflammatory drug or corticosteroid requirements found that six demonstrated reduced requirements. Overall, omega-3 fatty acids appear to reduce tender joint counts in individuals with rheumatoid arthritis and may reduce requirements for corticosteroids.

Omega-3 fatty acids and cognitive function, dementia, and neurological diseases

Omega-3 fatty acids appear to be important in brain development and function. Their effects on cognitive function in normal aging, incidence and treatment of dementia, incidence of several neurological diseases, and progression of multiple sclerosis were evaluated. A comprehensive search of the published and unpublished scientific-medical literature identified 12 studies that met inclusion criteria.

Multiple sclerosis and other neurological diseases

The quantity and strength of evidence for the effects of omega-3 fatty acids on cognitive function and decline, dementia, and neurological diseases vary greatly. Given the overall small number of studies and generally poor quality of clinical trials, substantive conclusions about the value of these compounds for these conditions cannot be drawn.

Omega-3 fatty acids for organ transplantation

Several laboratory, animal, and human studies suggest that omega-3 fatty acids from fish oil may improve outcomes in organ transplantation (e.g., decrease rejection; reduce hyperlipidemia, hypertension, and blood viscosity; and decrease the toxicity of the immunosuppressive agent cyclosporin A).

Resources

http://ods.od.nih.gov/factsheets/Omega3FattyAcidsandHealth-HealthProfessional/

Mixed Nuts

Chromium

What is Chromium?

Chromium is a mineral that humans require in trace amounts, although its mechanisms of action in the body and the amounts needed for optimal health are not well defined. It is found primarily in two forms: 1) trivalent (chromium 3+), which is biologically active and found in food, and 2) hexavalent (chromium 6+), a toxic form that results from industrial pollution. This fact sheet focuses exclusively on trivalent (3+) chromium.

Chromium is known to enhance the action of insulin, a hormone critical to the metabolism and storage of carbohydrate, fat, and protein in the body. In 1957, a compound in brewers’ yeast was found to prevent an age-related decline in the ability of rats to maintain normal levels of sugar (glucose) in their blood. Chromium was identified as the active ingredient in this so-called “glucose tolerance factor” in 1959.

Chromium also appears to be directly involved in carbohydrate, fat, and protein metabolism, but more research is needed to determine the full range of its roles in the body. The challenges to meeting this goal include:

  • Defining the types of individuals who respond to chromium supplementation;
  • Evaluating the chromium content of foods and its bioavailability;
  • Determining if a clinically relevant chromium-deficiency state exists in humans due to inadequate dietary intakes; and
  • Developing valid and reliable measures of chromium status.

What foods provide chromium?

Chromium is widely distributed in the food supply, but most foods provide only small amounts (less than 2 micrograms [mcg] per serving). Meat and whole-grain products, as well as some fruits, vegetables, and spices are relatively good sources. In contrast, foods high in simple sugars (like sucrose and fructose) are low in chromium.

Dietary intakes of chromium cannot be reliably determined because the content of the mineral in foods is substantially affected by agricultural and manufacturing processes and perhaps by contamination with chromium when the foods are analyzed. Therefore, Table 1, and food-composition databases generally, provide approximate values of chromium in foods that should only serve as a guide.

Table 1: Selected food sources of chromium
Food Chromium (mcg)
Broccoli, ½ cup 11
Grape juice, 1 cup 8
English muffin, whole wheat, 1 4
Potatoes, mashed, 1 cup 3
Garlic, dried, 1 teaspoon 3
Basil, dried, 1 tablespoon 2
Beef cubes, 3 ounces 2
Orange juice, 1 cup 2
Turkey breast, 3 ounces 2
Whole wheat bread, 2 slices 2
Red wine, 5 ounces 1–13
Apple, unpeeled, 1 medium 1
Banana, 1 medium 1
Green beans, ½ cup 1

What are recommended intakes of chromium?

Recommended chromium intakes are provided in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine of the National Academy of Sciences. Dietary Reference Intakes is the general term for a set of reference values to plan and assess the nutrient intakes of healthy people. These values include the Recommended Dietary Allowance (RDA) and the Adequate Intake (AI). The RDA is the average daily intake that meets a nutrient requirement of nearly all (97 to 98%) healthy individuals. An AI is established when there is insufficient research to establish an RDA; it is generally set at a level that healthy people typically consume.

In 1989, the National Academy of Sciences established an “estimated safe and adequate daily dietary intake” range for chromium. For adults and adolescents that range was 50 to 200 mcg. In 2001, DRIs for chromium were established. The research base was insufficient to establish RDAs, so AIs were developed based on average intakes of chromium from food as found in several studies. Chromium AIs are provided in Table 2.

Table 2: Adequate Intakes (AIs) for chromium
Age Infants and children
(mcg/day)
Males
(mcg/day)
Females
(mcg/day)
Pregnancy
(mcg/day)
Lactation
(mcg/day)
0 to 6 months 0.2
7 to 12 months 5.5
1 to 3 years 11
4 to 8 years 15
9 to 13 years 25 21
14 to 18 years 35 24 29 44
19 to 50 years 35 25 30 45
>50 years 30 20

mcg = micrograms

Adult women in the United States consume about 23 to 29 mcg of chromium per day from food, which meets their AIs unless they’re pregnant or lactating. In contrast, adult men average 39 to 54 mcg per day, which exceeds their AIs.

The average amount of chromium in the breast milk of healthy, well-nourished mothers is 0.24 mcg per quart, so infants exclusively fed breast milk obtain about 0.2 mcg (based on an estimated consumption of 0.82 quarts per day). Infant formula provides about 0.5 mcg of chromium per quart. No studies have compared how well infants absorb and utilize chromium from human milk and formula.

What affects chromium levels in the body?

Absorption of chromium from the intestinal tract is low, ranging from less than 0.4% to 2.5% of the amount consumed, and the remainder is excreted in the feces. Enhancing the mineral’s absorption are vitamin C (found in fruits and vegetables and their juices) and the B vitamin niacin (found in meats, poultry, fish, and grain products). Absorbed chromium is stored in the liver, spleen, soft tissue, and bone.

The body’s chromium content may be reduced under several conditions. Diets high in simple sugars (comprising more than 35% of calories) can increase chromium excretion in the urine. Infection, acute exercise, pregnancy and lactation, and stressful states (such as physical trauma) increase chromium losses and can lead to deficiency, especially if chromium intakes are already low.

When can a chromium deficiency occur?

Chromium has been found to correct glucose intolerance and insulin resistance in deficient animals, two indicators that the body is failing to properly control blood-sugar levels and which are precursors of type 2 diabetes. However, reports of actual chromium deficiency in humans are rare. Three hospitalized patients who were fed intravenously showed signs of diabetes (including weight loss, neuropathy, and impaired glucose tolerance) until chromium was added to their feeding solution. The chromium, added at doses of 150 to 250 mcg/day for up to two weeks, corrected their diabetes symptoms. Chromium is now routinely added to intravenous solutions.

Who may need extra chromium?

There are reports of significant age-related decreases in the chromium concentrations of hair, sweat and blood, which might suggest that older people are more vulnerable to chromium depletion than younger adults. One cannot be sure, however, as chromium status is difficult to determine. That’s because blood, urine, and hair levels do not necessarily reflect body stores. Furthermore, no chromium-specific enzyme or other biochemical marker has been found to reliably assess a person’s chromium status.

There is considerable interest in the possibility that supplemental chromium may help to treat impaired glucose tolerance and type 2 diabetes, but the research to date is inconclusive. No large, randomized, controlled clinical trials testing this hypothesis have been reported in the United States. Nevertheless, this is an active area of research.

What are some current issues and controversies about chromium?

Chromium has long been of interest for its possible connection to various health conditions. Among the most active areas of chromium research are its use in supplement form to treat diabetes, lower blood lipid levels, promote weight loss, and improve body composition.

Type 2 diabetes and glucose intolerance

In type 2 diabetes, the pancreas is usually producing enough insulin but, for unknown reasons, the body cannot use the insulin effectively. The disease typically occurs, in part, because the cells comprising muscle and other tissues become resistant to insulin’s action, especially among the obese. Insulin permits the entry of glucose into most cells, where this sugar is used for energy, stored in the liver and muscles (as glycogen), and converted to fat when present in excess. Insulin resistance leads to higher than normal levels of glucose in the blood (hyperglycemia).

Chromium deficiency impairs the body’s ability to use glucose to meet its energy needs and raises insulin requirements. It has therefore been suggested that chromium supplements might help to control type 2 diabetes or the glucose and insulin responses in persons at high risk of developing the disease. A review of randomized controlled clinical trials evaluated this hypothesis. This meta-analysis assessed the effects of chromium supplements on three markers of diabetes in the blood: glucose, insulin, and glycated hemoglobin (which provides a measure of long-term glucose levels; also known as hemoglobin A1C). It summarized data from 15 trials on 618 participants, of which 425 were in good health or had impaired glucose tolerance and 193 had type 2 diabetes. Chromium supplementation had no effect on glucose or insulin concentrations in the non-diabetic subjects nor did it reduce these levels in subjects with diabetes, except in one study. However, that study, conducted in China (in which 155 diabetics were given either 200 or 1,000 mcg/day of chromium or a placebo) might simply show the benefits of supplementation in a chromium-deficient population.

Overall, the value of chromium supplements for diabetics is inconclusive and controversia. Randomized controlled clinical trials in well-defined, at-risk populations where dietary intakes are known are necessary to determine the effects of chromium on markers of diabetes.

Lipid metabolism

The effects of chromium supplementation on blood lipid levels in humans are also inconclusive [1,8,37]. In some studies, 150 to 1,000 mcg/day has decreased total and low-density-lipoprotein (LDL or “bad”) cholesterol and triglyceride levels and increased concentrations of apolipoprotein A (a component of high-density-lipoprotein cholesterol known as HDL or “good” cholesterol) in subjects with atherosclerosis or elevated cholesterol or among those taking a beta-blocker drug. These findings are consistent with the results of earlier studies.

However, chromium supplements have shown no favorable effects on blood lipids in other studies. The mixed research findings may be due to difficulties in determining the chromium status of subjects at the start of the trials and the researchers’ failure to control for dietary factors that influence blood lipid levels.

Body weight and composition
Chromium supplements are sometimes claimed to reduce body fat and increase lean (muscle) mass. Yet a recent review of 24 studies that examined the effects of 200 to 1,000 mcg/day of chromium (in the form of chromium picolinate) on body mass or composition found no significant benefits. Another recent review of randomized, controlled clinical trials did find supplements of chromium picolinate to help with weight loss when compared to placebos, but the differences were small and of debatable clinical relevance. In several studies, chromium’s effects on body weight and composition may be called into question because the researchers failed to adequately control for the participants’ food intakes. Furthermore, most studies included only a small number of subjects and were of short duration.

What are the health risks of too much chromium?

Few serious adverse effects have been linked to high intakes of chromium, so the Institute of Medicine has not established a Tolerable Upper Intake Level (UL) for this mineral. A UL is the maximum daily intake of a nutrient that is unlikely to cause adverse health effects. It is one of the values (together with the RDA and AI) that comprise the Dietary Reference Intakes (DRIs) for each nutrient.

Chromium and medication interactions

Certain medications may interact with chromium, especially when taken on a regular basis (see Table 3). Before taking dietary supplements, check with your doctor or other qualified healthcare provider, especially if you take prescription or over-the-counter medications.

Table 3: Interactions between chromium and medications [14,52-54]
Medications Nature of interaction
  • Antacids
  • Corticosteroids
  • H2 blockers (such as cimetidine, famotidine, nizatidine, and rantidine)
  • Proton-pump inhibitors (such as omeprazole, lansoprazole, rabeprazole, pantoprazole, and esomeprazole)
These medications alter stomach acidity and may impair chromium absorption or enhance excretion
  • Beta-blockers (such as atenolol or propanolol)
  • Corticosteroids
  • Insulin
  • Nicotinic acid
  • Nonsteroidal anti-inflammatory drugs (NSAIDS)
  • Prostaglandin inhibitors (such as ibuprofen, indomethacin, naproxen, piroxicam, and aspirin)
These medications may have their effects enhanced if taken together with chromium or they may increase chromium absorption

Supplemental sources of chromium

Chromium is a widely used supplement. Chromium is sold as a single-ingredient supplement as well as in combination formulas, particularly those marketed for weight loss and performance enhancement.

The safety and efficacy of chromium supplements need more investigation. Please consult with a doctor or other trained healthcare professional before taking any dietary supplements.

Chromium supplements are available as chromium chloride, chromium nicotinate, chromium picolinate, high-chromium yeast, and chromium citrate. Chromium chloride in particular appears to have poor bioavailability. However, given the limited data on chromium absorption in humans, it is not clear which forms are best to take.

The Dietary Guidelines for Americans describes a healthy diet as one that:

  • Emphasizes a variety of fruits, vegetables,  whole grains and dairy (try and avoid too much dairy)
  • Whole grain products and certain fruits and vegetables like broccoli, potatoes, grape juice, and oranges are sources of chromium.
  • Includes lean meats, poultry, fish, beans, eggs, and nuts.
    Lean beef, oysters, eggs, and turkey are sources of chromium.
  • Is low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars.
  • Stays within your daily calorie needs.

Resources

http://ods.od.nih.gov/factsheets/Chromium-HealthProfessional/

Iodine

What is iodine and what does it do?

Iodine is a mineral found in some foods. The body needs iodine to make thyroid hormones. These hormones control the body’s metabolism and many other important functions. The body also needs thyroid hormones for proper bone and brain development during pregnancy and infancy. Getting enough iodine is important for everyone, especially infants and women who are pregnant.

How much iodine do I need?

The amount of iodine you need each day depends on your age. Average daily recommended amounts are listed below in micrograms (mcg).

Life Stage Recommended Amount
Birth to 6 months 110 mcg
Infants 7–12 months 130 mcg
Children 1–8 years 90 mcg
Children 9–13 years 120 mcg
Teens 14–18 years 150 mcg
Adults 150 mcg
Pregnant teens and women 220 mcg
Breastfeeding teens and women 290 mcg

 What foods provide iodine?

Iodine is found naturally in some foods and is also added to salt that is labeled as “iodized”. You can get recommended amounts of iodine by eating a variety of foods, including the following:

  • Fish (such as cod and tuna), seaweed, shrimp, and other seafood, which are generally rich in iodine.
  • Dairy products (such as milk, yogurt, and cheese) and products made from grains (like breads and cereals), which are the major sources of iodine in American diets.
  • Fruits and vegetables, which contain iodine, although the amount depends on the iodine in the soil where they grew and in any fertilizer that was used.
  • Iodized salt, which is readily available in the United States and many other countries. Processed foods, however, such as canned soups, almost never contain iodized salt.

What kinds of iodine dietary supplements are available?

Iodine is available in dietary supplements, usually in the form of potassium iodide or sodium iodide. Many multivitamin-mineral supplements contain iodine. Dietary supplements of iodine-containing kelp (a seaweed) are also available. However, for a healthy person with a nutritious and balanced diet, it should not be necessary to take supplements with iodine.

Am I getting enough iodine?

Most people get enough iodine from foods and beverages. However, certain groups of people are more likely than others to have trouble getting enough iodine:

  • People who do not use iodized salt. Adding iodine to salt is the most widely used strategy to control iodinedeficiency. Currently, about 70% of households worldwide use iodized salt.
  • Pregnant women. Women who are pregnant need about 50% more iodine than other women to provide enough iodine for their baby. Surveys show that many pregnant women in the United States may not get quite enough iodine, although experts do not know whether this affects their babies.
  • People living in regions with iodine-deficient soils who eat mostly local foods. These soils produce crops that have low iodine levels. Among the regions with the most iodine-poor soil are mountainous areas, such as the Himalayas, the Alps, and the Andes regions, as well as river valleys in South and Southeast Asia.
  • People who get marginal amounts of iodine and who also eat foods containing goitrogens. Goitrogens are substances that interfere with the way the body uses iodine. They are present in some plant foods includingsoy, and cruciferous vegetables such as cabbage, broccoli, cauliflower and Brussels sprouts. For most people in the United States who get adequate amounts of iodine, eating reasonable amounts of foods containing goitrogens is not a concern.

What happens if I don’t get enough iodine?

Iodine deficiency is uncommon in the western world. People who don’t get enough iodine cannot make sufficient amounts of thyroid hormone. This can cause many problems. In pregnant women, severe iodine deficiency can permanently harm the fetus by causing stunted growth, mental retardation, and delayed sexual development. Less severe iodine deficiency can cause lower-than-average IQ in infants and children and decrease adults’ ability to work and think clearly. Goiter, an enlarged thyroid gland, is often the first visible sign of iodine deficiency.

What are some effects of iodine on health?

Scientists are studying iodine to understand how it affects health. Here are some examples of what this research has shown.

Fetal and infant development

Women who are pregnant or breastfeeding need to get enough iodine for their babies to grow and develop properly. Breastfed infants get iodine from breast milk. However, the iodine content of breast milk depends on how much iodine the mother gets.

To make adequate amounts of iodine available for proper fetal and infant development, several national and international groups recommend that pregnant and breastfeeding women and infants take iodine supplements. In the United States and Canada, the American Thyroid Association recommends that pregnant and breastfeeding women take prenatal vitamin/mineral supplements containing iodine (150 mcg/day). However, only about half the prenatal multivitamins sold in the United States contain iodine.

Cognitive function during childhood

Severe iodine deficiency during childhood has harmful effects on the development of the brain and nervous system. The effects of mild iodine deficiency during childhood are more difficult to measure, but mild iodine deficiency might cause subtle problems with neurological development.

Giving iodine supplements to children with mild iodine deficiency improves their reasoning abilities and overall cognitive function. In children living in iodine-deficient areas, iodine supplements seem to improve both physical and mental development. More study is needed to fully understand the effects of mild iodine deficiency and of iodine supplements on cognitive function.

Fibrocystic breast disease

Although not harmful, fibrocystic breast disease causes lumpy, painful breasts. It mainly affects women of reproductive age but can also occur during menopause. Very high doses of iodine supplements might reduce the pain and other symptoms of fibrocystic breast disease, but more study is necessary to confirm this. Check with yourhealth care provider before taking iodine for this condition, especially because iodine can be unsafe at high doses.

Radiation-induced thyroid cancer

Nuclear accidents can release radioactive iodine into the environment, increasing the risk of thyroid cancer in people who are exposed to the radioactive iodine, especially children. People with iodine deficiency who are exposed to radioactive iodine are especially at risk of developing thyroid cancer. The U.S. Food and Drug Administration has approved potassium iodide as a thyroid-blocking agent to reduce the risk of thyroid cancer in radiation emergencies.

Can iodine be harmful?

Yes, if you get too much. Getting high levels of iodine can cause some of the same symptoms as iodine deficiency, including goiter (an enlarged thyroid gland). High iodine intakes can also cause thyroid gland inflammation and thyroid cancer. Getting a very large dose of iodine (several grams, for example) can cause burning of the mouth, throat, and stomach; fever; stomach pain; nausea; vomiting; diarrhea; weak pulse; and coma.

The safe upper limits for iodine are listed below. These levels do not apply to people who are taking iodine for medical reasons under the care of a doctor.

Life Stage Upper Safe Limit
Birth to 12 months: Not established
Children 1–3 years: 200 mcg
Children 4–8 years: 300 mcg
Children 9–13 years: 600 mcg
Teens 14–18 years: 900 mcg
Adults: 1,100 mcg

Are there any interactions with iodine that I should know about?

Yes. Iodine supplements can interact or interfere with medicines that you take. Here are several examples:

  • Iodine supplements might interact with anti-thyroid medications such as methimazole (Tapazole®), used totreat hyperthyroidism. Taking high doses of iodine with anti-thyroid medications could cause your body to produce too little thyroid hormone.
  • Taking potassium iodide with medicines for high blood pressure known as ACE inhibitors could raise the amount of potassium in your blood to an unsafe level. ACE inhibitors include benazepril (Lotensin®), lisinopril (Prinivil® and Zestril®), and fosinopril (Monopril®).
  • The amount of potassium in your blood can also get too high if you take potassium iodide with potassium-sparing diuretics, such as spironolactone (Aldactone®) and amiloride (Midamor®).

Resources

http://ods.od.nih.gov/factsheets/Iodine-QuickFacts/

Magnesium

What is Magnesium and it’s functions?

Magnesium is an essential mineral for human nutrition and serves several important functions:

  • Contraction and relaxation of muscles
  • Function of certain enzymes in the body
  • Production and transport of energy
  • Production of protein

Food Sources

Most dietary magnesium comes from vegetables, such as dark green, leafy vegetables. Other foods that are good sources of magnesium:

  • Fruits or vegetables (such as bananas, dried apricots, and avocados)
  • Nuts (such as almonds and cashews)
  • Peas and beans (legumes), seeds
  • Soy products (such as soy flour and tofu)
  • Whole grains (such as brown rice and millet)

Approximately 30% to 40% of the dietary magnesium consumed is typically absorbed by the body.

Selected Food Sources of Magnesium
Food Milligrams
(mg) per
serving
Percent
DV*
Almonds, dry roasted, 1 ounce 80 20
Spinach, boiled, ½ cup 78 20
Cashews, dry roasted, 1 ounce 74 19
Peanuts, oil roasted, ¼ cup 63 16
Cereal, shredded wheat, 2 large biscuits 61 15
Soymilk, plain or vanilla, 1 cup 61 15
Black beans, cooked, ½ cup 60 15
Edamame, shelled, cooked, ½ cup 50 13
Peanut butter, smooth, 2 tablespoons 49 12
Bread, whole wheat, 2 slices 46 12
Avocado, cubed, 1 cup 44 15
Potato, baked with skin, 3.5 ounces 43 11
Rice, brown, cooked, ½ cup 42 11
Yogurt, plain, low fat, 8 ounces 42 11
Breakfast cereals, fortified with 10% of the DV for magnesium 40 10
Oatmeal, instant, 1 packet 36 9
Kidney beans, canned, ½ cup 35 9
Banana, 1 medium 32 8
Salmon, Atlantic, farmed, cooked, 3 ounces 26 7
Milk, 1 cup 24–27 6–7
Halibut, cooked, 3 ounces 24 6
Raisins, ½ cup 23 6
Chicken breast, roasted, 3 ounces 22 6
Beef, ground, 90% lean, pan broiled, 3 ounces 20 5
Broccoli, chopped and cooked, ½ cup 12 3
Rice, white, cooked, ½ cup 10 3
Apple, 1 medium 9 2
Carrot, raw, 1 medium 7 2

Side Effects of too Much Magnesium

Side effects from increased magnesium intake are not common because the body removes excess amounts. Magnesium excess almost always occurs only when magnesium is supplemented as a medication.

Lack of magnesium (deficiency) is rare. The symptoms include:

  • Hyperexcitability
  • Muscle weakness
  • Sleepiness

Deficiency of magnesium can occur in people who abuse alcohol or in those who absorb less magnesium due to:

  • Burns
  • Certain medications
  • Low blood levels of calcium
  • Problems absorbing nutrients from the intestinal tract (malabsorption)
  • Surgery

Symptoms due to a lack of magnesium have three categories.

Early symptoms:

  • Anorexia
  • Apathy
  • Confusion
  • Fatigue
  • Insomnia
  • Irritability
  • Muscle twitching
  • Poor memory
  • Reduced ability to learn

Moderate deficiency symptoms:

  • Heart (cardiovascular) changes
  • Rapid heartbeat

Severe deficiency:

  • Continued muscle contraction
  • Delirium
  • Numbness
  • Seeing or hearing things that aren’t there (hallucinations)
  • Tingling

Recommendations

These are the recommended daily requirements of magnesium:

  • Children
    • 1 – 3 years old: 80 milligrams
    • 4 – 8 years old: 130 milligrams
    • 9 – 13 years old: 240 milligrams
    • 14 – 18 years old (boys): 410 milligrams
    • 14 – 18 years old (girls): 360 milligrams
  • Adult females: 310 – 320 milligrams
  • Pregnancy: 350 – 400 milligrams
  • Breastfeeding women: 310 – 360 milligrams
  • Adult males: 400 – 420 milligrams

Magnesium and Health

Habitually low intakes of magnesium induce changes in biochemical pathways that can increase the risk of illness over time. This section focuses on four diseases and disorders in which magnesium might be involved: hypertension and cardiovascular disease, type 2 diabetes, osteoporosis, and migraine headaches.

Hypertension and cardiovascular disease

Hypertension is a major risk factor for heart disease and stroke. Studies to date, however, have found that magnesium supplementation lowers blood pressure, at best, to only a small extent. A meta-analysis of 12 clinical trials found that magnesium supplementation for 8–26 weeks in 545 hypertensive participants resulted in only a small reduction (2.2 mmHg) in diastolic blood pressure. The dose of magnesium ranged from approximately 243 to 973 mg/day. A diet containing more magnesium because of added fruits and vegetables, more low-fat or non-fat dairy products, and less fat overall has proven to lower systolic and diastolic blood pressure by an average of 5.5 and 3.0 mmHg, respectively.

Several prospective studies have examined associations between magnesium intakes and heart disease.  A systematic review and meta-analysis of prospective studies found that higher serum levels of magnesium were significantly associated with a lower risk of cardiovascular disease, and higher dietary magnesium intakes (up to approximately 250 mg/day) were associated with a significantly lower risk of ischemic heart disease caused by a reduced blood supply to the heart muscle.

Higher magnesium intakes might reduce the risk of stroke. In a meta-analysis of 7 prospective trials with a total of 241,378 participants, an additional 100 mg/day magnesium in the diet was associated with an 8% decreased risk of total stroke, especially ischemic rather than hemorrhagic stroke.

Type 2 diabetes

Diets with higher amounts of magnesium are associated with a significantly lower risk of diabetes, possibly because of the important role of magnesium in glucose metabolism. Hypomagnesemia might worsen insulin resistance, a condition that often precedes diabetes, or it might be a consequence of insulin resistance. Diabetes leads to increased urinary losses of magnesium, and the subsequent magnesium inadequacy might impair insulin secretion and action, thereby worsening diabetes control.

Most investigations of magnesium intake and risk of type 2 diabetes have been prospective cohort studies. In 2008, the American Diabetes Association stated in its nutrition recommendations for people with diabetes, “Health care providers should focus on nutrition counseling rather than micronutrient supplementation in order to reach metabolic control of their patients.

Osteoporosis

Magnesium is involved in bone formation and influences the activities of osteoblasts and osteoclasts. Magnesium also affects the concentrations of both parathyroid hormone and the active form of vitamin D, which are major regulators of bone homeostasis. Several population-based studies have found positive associations between magnesium intake and bone mineral density in both men and women. Other research has found that women with osteoporosis have lower serum magnesium levels than women with osteopenia and those who do not have osteoporosis or osteopenia. These and other findings indicate that magnesium deficiency might be a risk factor for osteoporosis.

Migraine headaches

Magnesium deficiency is related to factors that promote headaches, including neurotransmitter release and vasoconstriction. People who experience migraine headaches have lower levels of serum and tissue magnesium than those who do not.

However, research on the use of magnesium supplements to prevent or reduce symptoms of migraine headaches is limited.

In their evidence-based guideline update, the American Academy of Neurology and the American Headache Society concluded that magnesium therapy is “probably effective” for migraine prevention. Because the typical dose of magnesium used for migraine prevention exceeds the UL (upper limit), this treatment should be used only under the direction and supervision of a healthcare provider.

Resources

http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/

http://www.nlm.nih.gov/medlineplus/ency/article/002423.htm

Coenzyme Q10

Although several naturally occurring forms of coenzyme Q have been identified, Q10 is the predominant form found in humans and most mammals, and it is the form most studied for therapeutic potential.

What is Coenzyme Q10 ?

  • Coenzyme Q10 is made naturally by the human body.
  • Coenzyme Q10 helps cells to produce energy, and it acts as an antioxidant.
  • Coenzyme Q10 has shown an ability to stimulate the immune system and to protect the heart from damage caused by certain chemotherapy drugs.
  • Low blood levels of coenzyme Q10 have been detected in patients with some types of cancer.
  • No report of a randomized clinical trial of coenzyme Q10 as a treatment for cancer has been published in a peer-reviewed scientific journal.
  • Coenzyme Q10 is marketed in the United States as a dietary supplement.

What foods contains Coenzyme Q10?

Meat and Fish

Relatively good food-based sources of CoQ10 include animal products such as beef, pork and chicken with organ meats such as the heart ranking highest. Oily fish such as sardines, herring, salmon and mackerel offer useful quantities of dietary CoQ10. According to the Linus Pauling Institute at Oregon State University, a 3 oz. serving of fried beef contains 2.6 mg of CoQ10 with herring offering 2.3 mg and fried chicken 1.4 mg. Getting all the CoQ10 needed from food presents challenges because of the relatively low amounts available even in foods with the highest content values.

Oils

Two cooking oils provide CoQ10: canola and soybean. Soybean oil contains polyunsaturated fatty acids and a tbsp of soybean oil provides 1.3 mg of CoQ10. To ensure a healthy lifestyle, stay away from hydrogenated soybean oils; select instead the new, low-saturate soybean varieties. Nutritionists and health care providers including those from MayoClinic.com recommend canola oil for its low saturated fat and high proportion of monounsaturated fat. A tablespoon of canola oil provides 1 mg of CoQ10.

Fruits and Vegetables

Small amounts of CoQ10 (less than .5 mg per serving) come from fruits and vegetables. The best sources include spinach, cauliflower and broccoli with strawberries a distant fourth providing only .1 mg in a 1/2 cup serving. Although frying vegetables reduces CoQ10 by approximately 14 to 32 percent, the vegetable’s CoQ10 content did not change when boiled. Adding pistachios or peanuts to vegetable dishes increases the CoQ10 available.

Resources

http://www.cancer.gov/cancertopics/pdq/cam/coenzymeQ10/HealthProfessional

http://www.livestrong.com/article/256149-what-foods-are-rich-in-coq10/

Vitamin B6

What is vitamin B6 and what does it do?

Vitamin B6 is a vitamin that is naturally present in many foods. The body needs vitamin B6 for more than 100 enzyme reactions involved in metabolism. Vitamin B6 is also involved in brain development during pregnancy and infancy as well as immune function.

How much vitamin B6 do I need?

The amount of vitamin B6 you need depends on your age. Average daily recommended amounts are listed below in milligrams (mg).

Life Stage Recommended Amount
Birth to 6 months 0.1 mg
Infants 7–12 months 0.3 mg
Children 1–3 years 0.5 mg
Children 4–8 years 0.6 mg
Children 9–13 years 1.0 mg
Teens 14–18 years (boys) 1.3 mg
Teens 14–18 years (girls) 1.2 mg
Adults 19–50 years 1.3 mg
Adults 51+ years (men) 1.7 mg
Adults 51+ years (women) 1.5 mg
Pregnant teens and women 1.9 mg
Breastfeeding teens and women 2.0 mg

What foods provide vitamin B6?

Vitamin B6 is found naturally in many foods and is added to other foods. You can get recommended amounts of vitamin B6 by eating a variety of foods, including the following:

  • Poultry, fish, and organ meats, all rich in vitamin B6.
  • Potatoes and other starchy vegetables.
  • Avocado
  • Lentils, chickpeas, beans
  • Fruit (other than citrus)

What kinds of vitamin B6 dietary supplements are available?

Vitamin B6 is available in dietary supplements, usually in the form of pyridoxine. Most multivitamin-mineral supplements contain vitamin B6. Dietary supplements that contain only vitamin B6, or vitamin B6 with other B vitamins, are also available.

Am I getting enough vitamin B6?

Most people in the United States get enough vitamin B6 from the foods they eat. However, certain groups of people are more likely than others to have trouble getting enough vitamin B6:

  • People whose kidneys do not work properly, including people who are on kidney dialysis and those who have had a kidney transplant.
  • People with autoimmune disorders, which cause their immune system to mistakenly attack their own healthy tissues. For example, people with rheumatoid arthritis, celiac disease, Crohn’s disease, ulcerative colitis, or inflammatory bowel disease sometimes have low vitamin B6 levels.
  • People with alcohol dependence.

What happens if I don’t get enough vitamin B6?

Vitamin B6 deficiency is uncommon in the United States. People who don’t get enough vitamin B6 can have a range of symptoms, including anemia, itchy rashes, scaly skin on the lips, cracks at the corners of the mouth, and a swollen tongue. Other symptoms of very low vitamin B6 levels include depression, confusion, and a weak immune system. Infants who do not get enough vitamin B6 can become irritable or develop extremely sensitive hearing or seizures.

What are some effects of vitamin B6 on health?

Scientists are studying vitamin B6 to understand how it affects health. Here are some examples of what this research has shown.

Heart disease

Some scientists had thought that certain B vitamins (such as folic acid, vitamin B12, and vitamin B6) might reduce heart disease risk by lowering levels of homocysteine, an amino acid in the blood. Although vitamin B supplements do lower blood homocysteine, research shows that they do not actually reduce the risk or severity of heart disease or stroke.

Cancer

People with low levels of vitamin B6 in the blood might have a higher risk of certain kinds of cancer, such as colorectal cancer. But studies to date have not shown that vitamin B6 supplements can help prevent cancer or lower the chances of dying from this disease.

Cognitive Function

Some research indicates that elderly people who have higher blood levels of vitamin B6 have better memory. However, taking vitamin B6 supplements (alone or combined with vitamin B12 and/or folic acid) does not seem to improve cognitive function or mood in healthy people or in people with dementia.

Premenstrual Syndrome

Scientists aren’t yet certain about the potential benefits of taking vitamin B6 for premenstrual syndrome (PMS). But some studies show that vitamin B6 supplements could reduce PMS symptoms, including moodiness, irritability, forgetfulness, bloating, and anxiety.

Nausea and Vomiting in Pregnancy

At least half of all women experience nausea, vomiting, or both in the first few months of pregnancy. Based on the results of several studies, the American Congress of Obstetricians and Gynecologists (ACOG) recommends taking vitamin B6 supplements under a doctor’s care for nausea and vomiting during pregnancy.

Can vitamin B6 be harmful?

People almost never get too much vitamin B6 from food. But taking high levels of vitamin B6 from supplements for a year or longer can cause severe nerve damage, leading people to lose control of their bodily movements. The symptoms usually stop when they stop taking the supplements. Other symptoms of too much vitamin B6 include painful, unsightly skin patches, extreme sensitivity to sunlight, nausea, and heartburn.

The safe upper limits for vitamin B6 are listed below. These levels do not apply to people who are taking vitamin B6 for medical reasons under the care of a doctor.

Life Stage Upper Safe Limit
Birth to 12 months Not established
Children 1–3 years 30 mg
Children 4–8 years 40 mg
Children 9–13 years 60 mg
Teens 14–18 years 80 mg
Adults 100 mg

Are there any interactions with vitamin B6 that I should know about?

Yes, vitamin B6 supplements can interact or interfere with medicines that you take. Here are several examples:

  • Vitamin B6 supplements might interact with cycloserine (Seromycin®), an antibiotic used to treat tuberculosis, and worsen any seizures and nerve cell damage that the drug might cause.
  • Taking certain epilepsy drugs could decrease vitamin B6 levels and reduce the drugs’ ability to control seizures.
  • Taking theophylline (Aquaphyllin®, Elixophyllin®, Theolair®, Truxophyllin®, and many others) for asthma or another lung disease can reduce vitamin B6 levels and cause seizures.

Resources

http://ods.od.nih.gov/factsheets/VitaminB6-QuickFacts/

Vitamin K

What is Vitamin K?

Vitamin K is a fat-soluble vitamin.

Function

Vitamin K is known as the clotting vitamin, because without it blood would not clot. Some studies suggest that it helps maintain strong bones in the elderly.

Food Sources

The best way to get the daily requirement of vitamin K is by eating food sources. Vitamin K is found in the following foods:

  • Green leafy vegetables, such as kale, spinach, turnip greens, collards, Swiss chard, mustard greens, parsley, romaine, and green leaf lettuce
  • Vegetables such as Brussels sprouts, broccoli, cauliflower, and cabbage
  • Fish, liver, meat, eggs, and cereals (contain smaller amounts)

Vitamin K is also made by the bacteria that line the gastrointestinal tract.

Side Effects

Vitamin K deficiency is very rare. It occurs when the body can’t properly absorb the vitamin from the intestinal tract. Vitamin K deficiency can also occur after long-term treatment with antibiotics.

People with vitamin K deficiency are usually more likely to have bruising and bleeding.

If you take blood thinning drugs (such as anticoagulant/antiplatelet drugs), you may need to limit vitamin K foods. You should know that vitamin K or foods containing vitamin K can affect how these drugs work.

It is important for you to keep vitamin K levels in your blood about the same from day to day. Ask your health care provider how much vitamin K-containing foods you should eat.

Recommendations

The Food and Nutrition Board at the Institute of Medicine Recommended Intakes for Individuals – Adequate Intakes (AIs) for vitamin K:

Infants

  • 0 – 6 months: 2.0 micrograms per day (mcg/day)
  • 7 – 12 months: 2.5 mcg/day

Children

  • 1 – 3 years: 30 mcg/day
  • 4 – 8 years: 55 mcg/day
  • 9 – 13 years: 60 mcg/day

Adolescents and Adults

  • Males and females age 14 – 18: 75 mcg/day
  • Males and females age 19 and older: 90 mcg/day

Resources

http://www.nlm.nih.gov/medlineplus/ency/article/002407.htm

parsley

Vitamin C

What is vitamin C and what does it do?

Vitamin C, also known as ascorbic acid, is a water-soluble nutrient found in some foods. In the body, it acts as anantioxidant, helping to protect cells from the damage caused by free radicals. Free radicals are compounds formed when our bodies convert the food we eat into energy. People are also exposed to free radicals in the environment from cigarette smoke, air pollution, and ultraviolet light from the sun.

The body also needs vitamin C to make collagen, a protein required to help wounds heal. In addition, vitamin C improves the absorption of iron from plant-based foods and helps the immune system work properly to protect the body from disease.

How much vitamin C do I need?

The amount of vitamin C you need each day depends on your age. Average daily recommended amounts for different ages are listed below in milligrams (mg).

Life Stage Recommended Amount
Birth to 6 months 40 mg
Infants 7–12 months 50 mg
Children 1–3 years 15 mg
Children 4–8 years 25 mg
Children 9–13 years 45 mg
Teens 14–18 years (boys) 75 mg
Teens 14–18 years (girls) 65 mg
Adults (men) 90 mg
Adults (women) 75 mg
Pregnant teens 80 mg
Pregnant women 85 mg
Breastfeeding teens 115 mg
Breastfeeding women 120 mg

If you smoke, add 35 mg to the above values to calculate your total daily recommended amount.

What foods provide vitamin C?

Fruits and vegetables are the best sources of vitamin C. You can get recommended amounts of vitamin C by eating a variety of foods including the following:

  • Citrus fruits (such as oranges and grapefruit) and their juices, as well as capsicum (which has almost three times the amount of vitamin c than oranges) and kiwifruit.
  • Broccoli, strawberries, cantaloupe
  • Some foods and beverages that are fortified with vitamin C – read the product labels.

The vitamin C content of food may be reduced by prolonged storage and by cooking. Steaming may lessen cooking losses. Fortunately, many of the best food sources of vitamin C, such as fruits and vegetables, are usually eaten raw.

What kinds of vitamin C dietary supplements are available?

Most multivitamins have vitamin C. Vitamin C is also available alone as a dietary supplement or in combination with other nutrients. The vitamin C in dietary supplements is usually in the form of ascorbic acid, but some supplements have other forms, such as sodium ascorbate, calcium ascorbate, other mineral ascorbates, and ascorbic acid with bioflavonoids. Research has not shown that any form of vitamin C is better than the other forms. Through a healthy diet with lots of fruits and vegetables is should not be necessary to take Vitamin C supplements.

Am I getting enough vitamin C?

Most people in the United States get enough vitamin C from foods and beverages. However, certain groups of people are more likely than others to have trouble getting enough vitamin C:

  • People who smoke and those who are exposed to secondhand smoke, in part because smoke increases the amount of vitamin C that the body needs to repair damage caused by free radicals. People who smoke need 35 mg more vitamin C per day than nonsmokers.
  • Infants who are fed evaporated or boiled cow’s milk, because cow’s milk has very little vitamin C and heat can destroy vitamin C. Cow’s milk is not recommended for infants under 1 year of age. Breast milk and infant formula have adequate amounts of vitamin C.
  • People who eat a very limited variety of food.
  • People with certain medical conditions such as severe malabsorption, some types of cancer, and kidney diseaserequiring hemodialysis.

What happens if I don’t get enough vitamin C?

Vitamin C deficiency is rare in the United States and Canada. People who get little or no vitamin C (below about 10 mg per day) for many weeks can get scurvy. Scurvy causes fatigue, inflammation of the gums, small red or purple spots on the skin, joint pain, poor wound healing, and corkscrew hairs. Additional signs of scurvy include depressionas well as swollen, bleeding gums and loosening or loss of teeth. People with scurvy can also develop anemia. Scurvy is fatal if it is not treated.

What are some effects of vitamin C on health?

Scientists are studying vitamin C to understand how it affects health. Here are several examples of what this research has shown.

Cancer prevention and treatment

People with high intakes of vitamin C from fruits and vegetables might have a lower risk of getting many types of cancer, such as lung, breast, and colon cancer. However, taking vitamin C supplements, with or without other antioxidants, doesn’t seem to protect people from getting cancer.

It is not clear whether taking high doses of vitamin C is helpful as a treatment for cancer. Vitamin C’s effects appear to depend on how it is administered to the patient. Oral doses of vitamin C can’t raise blood levels of vitamin C nearly as high as intravenous doses given through injections. A few studies in animals and test tubes indicate that very high blood levels of vitamin C might shrink tumors. But more research is needed to determine whether high-dose intravenous vitamin C helps treat cancer in people.

Vitamin C dietary supplements and other antioxidants might interact with chemotherapy and radiation therapy for cancer. People being treated for cancer should talk with their oncologist before taking vitamin C or other antioxidant supplements, especially in high doses.

Cardiovascular disease

People who eat lots of fruits and vegetables seem to have a lower risk of cardiovascular disease. Researchers believe that the antioxidant content of these foods might be partly responsible for this association because oxidative damageis a major cause of cardiovascular disease. However, scientists aren’t sure whether vitamin C itself, either from food or supplements, helps protect people from cardiovascular disease. It is also not clear whether vitamin C helps prevent cardiovascular disease from getting worse in people who already have it.

Age-related macular degeneration (AMD) and cataracts

AMD and cataracts are two of the leading causes of vision loss in older people. Researchers do not believe that vitamin C and other antioxidants affect the risk of getting AMD. However, research suggests that vitamin C combined with other nutrients might help keep early AMD from worsening into advanced AMD.

In a large study, older people with AMD who took a daily dietary supplement with 500 mg vitamin C, 80 mg zinc, 400 IU vitamin E, 15 mg beta-carotene, and 2 mg copper for about 6 years had a lower chance of developing advanced AMD. They also had less vision loss than those who did not take the dietary supplement.

More research is needed before doctors can recommend dietary supplements containing vitamin C for patients with AMD. However, people who have or are developing the disease might want to talk with their doctor about taking dietary supplements.

The relationship between vitamin C and cataract formation is unclear. Some studies show that people who get more vitamin C from foods have a lower risk of getting cataracts. But further research is needed to clarify this association and to determine whether vitamin C supplements affect the risk of getting cataracts.

The common cold

Although vitamin C has long been a popular remedy for the common cold, research shows that for most people, vitamin C supplements do not reduce the risk of getting the common cold. However, people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms when they do have a cold. Using vitamin C supplements after cold symptoms start does not appear to be helpful.

Can vitamin C be harmful?

Taking too much vitamin C can cause diarrhea, nausea, and stomach cramps. In people with a condition calledhemochromatosis, which causes the body to store too much iron, high doses of vitamin C could worsen iron overload and damage body tissues.

The safe upper limits for vitamin C are listed below:

Life Stage Upper Safe Limit
Birth to 12 months Not established
Children 1–3 years 400 mg
Children 4–8 years 650 mg
Children 9–13 years 1,200 mg
Teens 14–18 years 1,800 mg
Adults 2,000 mg

Are there any interactions with vitamin C that I should know about?

Vitamin C dietary supplements can interact or interfere with medicines that you take. Here are several examples:

  • Vitamin C dietary supplements might interact with cancer treatments, such as chemotherapy and radiation therapy. It is not clear whether vitamin C might have the unwanted effect of protecting tumor cells from cancer treatments or whether it might help protect normal tissues from getting damaged. If you are being treated for cancer, check with your health care provider before taking vitamin C or other antioxidant supplements, especially in high doses.
  • In one study, vitamin C plus other antioxidants (such as vitamin E, selenium, and beta-carotene) reduced the heart-protective effects of two drugs taken in combination (a statin and niacin) to control blood-cholesterollevels. It is not known whether this interaction also occurs with other statins. Health care providers should monitor lipid levels in people taking both statins and antioxidant supplements.

Where to buy Vitamin C

Vitamin C is available in bulk from from online supplement retailers like Powdercity.com. They offer Vitamin C Supplements (Ascorbic Acid) in variants of: 100g, 500g and 1kg. All of their products are 3rd party lab tested and they offer free shipping to orders over $25 in the US!

Resources

http://ods.od.nih.gov/factsheets/VitaminC-QuickFacts/

Iron

Iron: What is it?

Iron, one of the most abundant metals on Earth, is essential to most life forms and to normal human physiology. Iron is an integral part of many proteins and enzymes that maintain good health. In humans, iron is an essential component of proteins involved in oxygen transport. It is also essential for the regulation of cell growth and differentiation. A deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work performance, and decreased immunity. On the other hand, excess amounts of iron can result in toxicity and even death.

Almost two-thirds of iron in the body is found in hemoglobin, the protein in red blood cells that carries oxygen to tissues. Smaller amounts of iron are found in myoglobin, a protein that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions. Iron is also found in proteins that store iron for future needs and that transport iron in blood. Iron stores are regulated by intestinal iron absorption.

What foods provide iron?

There are two forms of dietary iron: heme and nonheme. Heme iron is derived from hemoglobin, the protein in red blood cells that delivers oxygen to cells. Heme iron is found in animal foods that originally contained hemoglobin, such as red meats, fish, and poultry. Iron in plant foods such as lentils and beans is arranged in a chemical structure called nonheme iron. This is the form of iron added to iron-enriched and iron-fortified foods. Heme iron is absorbed better than nonheme iron, but most dietary iron is nonheme iron. A variety of heme and nonheme sources of iron are listed in Tables 1 and 2.

Table 1: Selected Food Sources of Heme Iron
Food Milligrams
per serving
% DV*
Chicken liver, pan-fried, 3 ounces 11.0 61
Oysters, canned, 3 ounces 5.7 32
Beef liver, pan-fried, 3 ounces 5.2 29
Beef, chuck, blade roast, lean only, braised, 3 ounces 3.1 17
Turkey, dark meat, roasted, 3 ounces 2.0 11
Beef, ground, 85% lean, patty, broiled, 3 ounces 2.2 12
Beef, top sirloin, steak, lean only, broiled, 3 ounces 1.6 9
Tuna, light, canned in water, 3 ounces 1.3 7
Turkey, light meat, roasted, 3 ounces 1.1 6
Chicken, dark meat, meat only, roasted, 3 ounces 1.1 6
Chicken, light meat, meat only, roasted, 3 ounces 0.9 5
Tuna, fresh, yellowfin, cooked, dry heat, 3 ounces 0.8 4
Crab, Alaskan king, cooked, moist heat, 3 ounces 0.7 4
Pork, loin chop, broiled, 3 ounces 0.7 4
Shrimp, mixed species, cooked, moist heat, 4 large 0.3 2
Halibut, cooked, dry heat, 3 ounces 0.2 1
Table 2: Selected Food Sources of Nonheme Iron
Food Milligrams
per serving
% DV*
Ready-to-eat cereal, 100% iron fortified, ¾ cup 18.0 100
Oatmeal, instant, fortified, prepared with water, 1 packet 11.0 61
Soybeans, mature, boiled, 1 cup 8.8 48
Lentils, boiled, 1 cup 6.6 37
Beans, kidney, mature, boiled, 1 cup 5.2 29
Beans, lima, large, mature, boiled, 1 cup 4.5 25
Ready-to-eat cereal, 25% iron fortified, ¾ cup 4.5 25
Blackeye peas, (cowpeas), mature, boiled, 1 cup 4.3 24
Beans, navy, mature, boiled, 1 cup 4.3 24
Beans, black, mature, boiled, 1 cup 3.6 20
Beans, pinto, mature, boiled, 1 cup 3.6 21
Tofu, raw, firm, ½ cup 3.4 19
Spinach, fresh, boiled, drained, ½ cup 3.2 18
Spinach, canned, drained solids ½ cup 2.5 14
Spinach, frozen, chopped or leaf, boiled ½ cup 1.9 11
Raisins, seedless, packed, ½ cup 1.6 9
Grits, white, enriched, quick, prepared with water, 1 cup 1.5 8
Molasses, 1 tablespoon 0.9 5
Bread, white, commercially prepared, 1 slice 0.9 5
Bread, whole-wheat, commercially prepared, 1 slice 0.7 4

*DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for iron is 18 milligrams (mg). A food providing 5% of the DV or less is a low source while a food that provides 10–19% of the DV is a good source. A food that provides 20% or more of the DV is high in that nutrient. It is important to remember that foods that provide lower percentages of the DV also contribute to a healthful diet.

What affects iron absorption?

Iron absorption refers to the amount of dietary iron that the body obtains and uses from food. Healthy adults absorb about 10% to 15% of dietary iron, but individual absorption is influenced by several factors.

Storage levels of iron have the greatest influence on iron absorption. Iron absorption increases when body stores are low. When iron stores are high, absorption decreases to help protect against toxic effects of iron overload. Iron absorption is also influenced by the type of dietary iron consumed. Absorption of heme iron from meat proteins is efficient. Absorption of heme iron ranges from 15% to 35%, and is not significantly affected by diet. In contrast, 2% to 20% of nonheme iron in plant foods such as rice, maize, black beans, soybeans and wheat is absorbed. Nonheme iron absorption is significantly influenced by various food components.

Meat proteins and vitamin C will improve the absorption of nonheme iron. Tannins (found in tea), calcium, polyphenols, and phytates (found in legumes and whole grains) can decrease absorption of nonheme iron. Some proteins found in soybeans also inhibit nonheme iron absorption. It is most important to include foods that enhance nonheme iron absorption when daily iron intake is less than recommended, when iron losses are high (which may occur with heavy menstrual losses), when iron requirements are high (as in pregnancy), and when only vegetarian nonheme sources of iron are consumed.

What is the recommended intake for iron?

Recommended Dietary Allowances (RDA), Adequate Intakes (AI), andTolerable Upper Intake Levels (UL).

Recommended Dietary Allowances for Iron for Infants 
Age Males
(mg/day)
Females
(mg/day)
Pregnancy
(mg/day)
Lactation
(mg/day)
7 to 12 months 11 11 N/A N/A
1 to 3 years 7 7 N/A N/A
4 to 8 years 10 10 N/A N/A
9 to 13 years 8 8 N/A N/A
14 to 18 years 11 15 27 10
19 to 50 years 8 18 27 9
51+ years 8 8 N/A N/A

Healthy full term infants are born with a supply of iron that lasts for 4 to 6 months. There is not enough evidence available to establish a RDA for iron for infants from birth through 6 months of age. Recommended iron intake for this age group is based on an Adequate Intake (AI) that reflects the average iron intake of healthy infants fed breast milk.

Iron in human breast milk is well absorbed by infants. It is estimated that infants can use greater than 50% of the iron in breast milk as compared to less than 12% of the iron in infant formula. The amount of iron in cow’s milk is low, and infants poorly absorb it. Feeding cow’s milk to infants also may result in gastrointestinal bleeding. For these reasons, cow’s milk should not be fed to infants until they are at least 1 year old.

Iron intake is negatively influenced by low nutrient density foods, which are high in calories but low in vitamins and minerals. Sugar sweetened sodas and most desserts are examples of low nutrient density foods, as are snack foods such as potato chips.

When can iron deficiency occur?

The World Health Organization considers iron deficiency the number one nutritional disorder in the world. As many as 80% of the world’s population may be iron deficient, while 30% may have iron deficiency anemia.

Iron deficiency develops gradually and usually begins with a negative iron balance, when iron intake does not meet the daily need for dietary iron.

Iron deficiency anemia can be associated with low dietary intake of iron, inadequate absorption of iron, or excessive blood loss. Women of childbearing age, pregnant women, preterm and low birth weight infants, older infants and toddlers, and teenage girls are at greatest risk of developing iron deficiency anemia because they have the greatest need for iron. Women with heavy menstrual losses can lose a significant amount of iron and are at considerable risk for iron deficiency. Adult men and post-menopausal women lose very little iron, and have a low risk of iron deficiency.

Vitamin A helps mobilize iron from its storage sites, so a deficiency of vitamin A limits the body’s ability to use stored iron. This results in an “apparent” iron deficiency because hemoglobin levels are low even though the body can maintain normal amounts of stored iron.

Signs of iron deficiency anemia include :

  • feeling tired and weak
  • decreased work and school performance
  • slow cognitive and social development during childhood
  • difficulty maintaining body temperature
  • decreased immune function, which increases susceptibility to infection
  • glossitis (an inflamed tongue)

Eating nonnutritive substances such as dirt and clay, often referred to as pica or geophagia, is sometimes seen in persons with iron deficiency. There is disagreement about the cause of this association.

Who may need extra iron to prevent a deficiency?

Three groups of people are most likely to benefit from iron supplements: people with a greater need for iron, individuals who tend to lose more iron, and people who do not absorb iron normally. These individuals include:

  • pregnant women
  • preterm and low birth weight infants
  • older infants and toddlers
  • teenage girls
  • women of childbearing age, especially those with heavy menstrual losses
  • people with renal failure, especially those undergoing routine dialysis
  • people with gastrointestinal disorders who do not absorb iron normally

Total dietary iron intake in vegetarian diets may meet recommended levels; however that iron is less available for absorption than in diets that include meat. Vegetarians who exclude all animal products from their diet may need almost twice as much dietary iron each day as non-vegetarians because of the lower intestinal absorption of nonheme iron in plant foods. Vegetarians should consider consuming nonheme iron sources together with a good source of vitamin C, such as citrus fruits, to improve the absorption of nonheme iron.

Does pregnancy increase the need for iron?

Nutrient requirements increase during pregnancy to support fetal growth and maternal health. Iron requirements of pregnant women are approximately double that of non-pregnant women because of increased blood volume during pregnancy, increased needs of the fetus, and blood losses that occur during delivery.

Low levels of hemoglobin and hematocrit may indicate iron deficiency. Hemoglobin is the protein in red blood cells that carries oxygen to tissues. Hematocrit is the proportion of whole blood that is made up of red blood cells. Nutritionists estimate that over half of pregnant women in the world may have hemoglobin levels consistent with iron deficiency.

Some facts about iron supplements

Iron supplementation is indicated when diet alone cannot restore deficient iron levels to normal within an acceptable timeframe. Supplements are especially important when an individual is experiencing clinical symptoms of iron deficiency anemia. The goals of providing oral iron supplements are to supply sufficient iron to restore normal storage levels of iron and to replenish hemoglobin deficits. When hemoglobin levels are below normal, physicians often measure serum ferritin, the storage form of iron. A serum ferritin level less than or equal to 15 micrograms per liter confirms iron deficiency anemia in women, and suggests a possible need for iron supplementation.

Supplemental iron is available in two forms: ferrous and ferric. Ferrous iron salts (ferrous fumarate, ferrous sulfate, and ferrous gluconate) are the best absorbed forms of iron supplements .

The amount of iron absorbed decreases with increasing doses. For this reason, it is recommended that most people take their prescribed daily iron supplement in two or three equally spaced doses.

Therapeutic doses of iron supplements, which are prescribed for iron deficiency anemia, may cause gastrointestinal side effects such as nausea, vomiting, constipation, diarrhea, dark colored stools, and/or abdominal distress .

Who should be cautious about taking iron supplements?

Iron deficiency is uncommon among adult men and postmenopausal women. These individuals should only take iron supplements when prescribed by a physician because of their greater risk of iron overload. Iron overload is a condition in which excess iron is found in the blood and stored in organs such as the liver and heart. Iron overload is associated with several genetic diseases including hemochromatosis, which affects approximately 1 in 250 individuals of northern European descent. Individuals with hemochromatosis absorb iron very efficiently, which can result in a build up of excess iron and can cause organ damage such as cirrhosis of the liver and heart failure. Hemochromatosis is often not diagnosed until excess iron stores have damaged an organ. Iron supplementation may accelerate the effects of hemochromatosis, an important reason why adult men and postmenopausal women who are not iron deficient should avoid iron supplements. Individuals with blood disorders that require frequent blood transfusions are also at risk of iron overload and are usually advised to avoid iron supplements.

What are some current issues and controversies about iron?

Iron and heart disease

Because known risk factors cannot explain all cases of heart disease, researchers continue to look for new causes. Some evidence suggests that iron can stimulate the activity of free radicals. Free radicals are natural by-products of oxygen metabolism that are associated with chronic diseases, including cardiovascular disease. Free radicals may inflame and damage coronary arteries, the blood vessels that supply the heart muscle. This inflammation may contribute to the development of atherosclerosis, a condition characterized by partial or complete blockage of one or more coronary arteries. Other researchers suggest that iron may contribute to the oxidation of LDL (“bad”) cholesterol, changing it to a form that is more damaging to coronary arteries.

As far back as the 1980s, some researchers suggested that the regular menstrual loss of iron, rather than a protective effect from estrogen, could better explain the lower incidence of heart disease seen in pre-menopausal women. After menopause, a woman’s risk of developing coronary heart disease increases along with her iron stores. Researchers have also observed lower rates of heart disease in populations with lower iron stores, such as those in developing countries. In those geographic areas, lower iron stores are attributed to low meat (and iron) intake, high fiber diets that inhibit iron absorption, and gastrointestinal (GI) blood (and iron) loss due to parasitic infections.

Conflicting results, and different methods to measure iron stores, make it difficult to reach a final conclusion on this issue. However, researchers know that it is feasible to decrease iron stores in healthy individual through phlebotomy (blood letting or donation). Using phlebotomy, researchers hope to learn more about iron levels and cardiovascular disease.

Iron and intense exercise

Many men and women who engage in regular, intense exercise such as jogging, competitive swimming, and cycling have marginal or inadequate iron status. Possible explanations include increased gastrointestinal blood loss after running and a greater turnover of red blood cells. Also, red blood cells within the foot can rupture while running. For these reasons, the need for iron may be 30% greater in those who engage in regular intense exercise.

Three groups of athletes may be at greatest risk of iron depletion and deficiency: female athletes, distance runners, and vegetarian athletes. It is particularly important for members of these groups to consume recommended amounts of iron and to pay attention to dietary factors that enhance iron absorption. If appropriate nutrition intervention does not promote normal iron status, iron supplementation may be indicated. In one study of female swimmers, researchers found that supplementation with 125 milligrams (mg) of ferrous sulfate per day prevented iron depletion. These swimmers maintained adequate iron stores, and did not experience the gastrointestinal side effects often seen with higher doses of iron supplementation.

Iron and mineral interactions

Some researchers have raised concerns about interactions between iron, zinc, and calcium. When iron and zinc supplements are given together in a water solution and without food, greater doses of iron may decrease zinc absorption. However, the effect of supplemental iron on zinc absorption does not appear to be significant when supplements are consumed with food.There is evidence that calcium from supplements and dairy foods may inhibit iron absorption, but it has been very difficult to distinguish between the effects of calcium on iron absorption versus other inhibitory factors such as phytate.

What is the risk of iron toxicity?

There is considerable potential for iron toxicity because very little iron is excreted from the body. Thus, iron can accumulate in body tissues and organs when normal storage sites are full. For example, people with hemachromatosis are at risk of developing iron toxicity because of their high iron stores.

Table 5: Tolerable Upper Intake Levels for Iron for Infants 7 to 12 months, Children, and Adults 
Age Males
(mg/day)
Females
(mg/day)
Pregnancy
(mg/day)
Lactation
(mg/day)
7 to 12 months 40 40 N/A N/A
1 to 13 years 40 40 N/A N/A
14 to 18 years 45 45 45 45
19+ years 45 45 45 45

Resources

http://ods.od.nih.gov/factsheets/Iron-HealthProfessional/