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Search Health Information    Iron for Sports & Fitness

Iron for Sports & Fitness

Why Use

Iron

Why Do Athletes Use It?*

Some athletes say that iron helps boost energy levels.

What Do the Advocates Say?*

Athletes are not at risk of developing iron deficiency or anemia any more than others; however, metabolically, athletes utilize more minerals, including iron, than non-athletes do.

Women have a greater risk of developing iron deficiency than men. Premenopausal women, in particular, are at risk of becoming iron-deficient because of the blood loss that occurs every month during menstruation.

Doctors often screen for iron deficiency by testing for anemia. However, individuals who have a mild deficiency of iron may not be anemic, since blood counts do not typically drop until iron stores in the body are almost completely depleted. If you suspect you are deficient in iron, ask your doctor to perform a more specific blood test, known as a “ferritin” test, rather than the routine “CBC” or “total iron” tests.

Prior to taking supplemental iron, people should be tested by a doctor to make sure such supplementation is appropriate. Although supplemental iron may help those who are deficient, too much iron may cause adverse side effects, including stomach and intestinal cramps, nausea, and constipation.

*Athletes and fitness advocates may claim benefits for this supplement based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles.

Dosage & Side Effects

Iron

How Much Is Usually Taken by Athletes?

Iron is important for an athlete because it is a component of hemoglobin, which transports oxygen to muscle cells. Some athletes, especially women, do not get enough iron in their diet. In addition, for reasons that are unclear, endurance athletes, such as marathon runners, frequently have low body-iron levels.1 , 2 , 3 However, anemia in athletes is often not due to iron deficiency and may be a normal adaptation to the stress of exercise.4 Supplementing with iron is usually unwise unless a deficiency has been diagnosed. People who experience undue fatigue (an early warning sign of iron deficiency) should have their iron status evaluated by a doctor. Athletes who are found to be iron deficient by a physician are typically given 100 mg per day until blood tests indicate they are no longer deficient. Supplementing iron-deficient athletes with 100 to 200 mg per day of iron increased aerobic exercise performance in some,5 , 6 , 7 though not all,8 , 9 double-blind studies. A recent double-blind trial found that iron-deficient women who took 20 mg per day of iron for six weeks were able to perform knee strength exercises for a longer time without muscle fatigue compared with those taking a placebo.10

Side Effects

Caution: Iron (ferrous sulfate) is the leading cause of accidental poisonings in children.11 , 12 , 13 The incidence of iron poisonings in young children increased dramatically in 1986. Many of these children obtained the iron from a child-resistant container opened by themselves or another child, or left open or improperly closed by an adult.14 Deaths in children have occurred from ingesting as little as 200 mg to as much as 5.85 grams of iron.15 Keep iron-containing supplements out of a child’s reach.

Hemochromatosis, hemosiderosis, polycythemia, and iron-loading anemias (such as thalassemia and sickle cell anemia ) are conditions involving excessive storage of iron. Supplementing iron can be quite dangerous for people with these diseases.

Supplemental amounts required to overcome iron deficiency can cause constipation . Sometimes switching the form of iron (see “Which forms of supplemental iron are best?” above), getting more exercise, or treating the constipation with fiber and fluids is helpful, though fiber can reduce iron absorption (see below). Sometimes the amount of iron must be reduced if constipation occurs.

Some researchers have linked excess iron levels to diabetes ,16cancer,17 increased risk of infection ,18 systemic lupus erythematosus (SLE),19 exacerbation of rheumatoid arthritis ,20 and Huntington’s disease.21 The greatest concern has surrounded the possibility that excess storage of iron in the body increases the risk of heart disease .22 , 23 , 24 Two analyses of published studies came to different conclusions about whether iron could increase heart disease risk.25 , 26 One trial has suggested that such a link may exist, but only in some people (possibly smokers or those with elevated cholesterol levels).27 The link between excess iron and any of the diseases mentioned earlier in this paragraph has not been definitively proven. Nonetheless, too much iron causes free radical damage , which can, in theory, promote or exacerbate most of these diseases. People who are not iron deficient should generally not take iron supplements.

Patients on kidney dialysis who are given injections of iron frequently experience “oxidative stress”. This is because iron is a pro-oxidant, meaning that it interacts with oxygen molecules in ways that can damage tissues. These adverse effects of iron therapy may be counteracted by supplementation with vitamin E .28

Supplementation with iron, or iron and zinc, has been found to improve vitamin A status among children at high risk for deficiency of the three nutrients. 29

People with hepatitis C who have failed to respond to interferon therapy have been found to have higher amounts of iron within the liver. Moreover, reduction of iron levels by drawing blood has been shown to decrease liver injury caused by hepatitis C.30 Therefore, people with hepatitis C should avoid iron supplements.

In some people, particularly those with diabetes , insulin resistance syndrome , or liver disease, a genetic susceptibility to iron overload has been reported.31

Interactions with Supplements, Foods, & Other Compounds

Many foods, beverages, and supplements have been shown to affect the absorption of iron.32

Foods, beverages and supplements that interfere with iron absorption include

  • Green tea  (Camellia sinensis).33 , 34 , 35 , 36 This effect may be desirable for people with iron overload diseases, such as hemochromatosis. The inhibitory effect of green tea on iron absorption was 26% in one study.37

  • Coffee (Coffea arabica, C. robusta).38 , 39 , 40

  • Red wine, particularly the polyphenol component (also found in tea).41 , 42 Since wine is also a dietary source of iron, it is not clear whether drinking red wine would lead to a deficiency of iron.

  • Phytate (phytic acid), found in unleavened wheat products such as matzoh, pita, and some rye crackers; in wheat germ, oats , nuts, cacao powder, vanilla extract, beans, and many other foods, and in IP-6 supplements.43 , 44 , 45

  • Whole wheat bran, independent of its phytate content, has been shown to inhibit iron absorption.46

  • Calcium from food and supplements interferes with heme-iron absorption.47 , 48

  • Soy protein.49 , 50

  • Eggs.51 , 52

Foods and supplements that increase iron absorption include

  • Meat, poultry, and fish.53 , 54 , 55 , 56 , 57

Although vitamin C increases iron absorption,58 , 59 , 60 , 61 the effect is relatively minor.62

Taking vitamin A with iron helps treat iron deficiency , since vitamin A improves the absorption and/or utilization of iron.63 , 64

Although soy protein has been shown to decrease iron absorption (see above), certain soy-containing foods (e.g. tofu, miso, tempeh) have significantly improved iron absorption.65 Some soy sauces may also enhance iron absorption.66

Alcohol, but not red wine, has been reported to increase the absorption of ferric, but not ferrous, iron.67 , 68

Iron has been reported to potentially interfere with manganese absorption. In one trial, women with high iron status had relatively poor absorption of manganese.69 In another trial studying manganese/iron interactions in women, increased intake of “non-heme iron”—the kind of iron found in most supplements—decreased manganese status.70 These interactions suggest that taking multiminerals that include manganese may protect against manganese deficiencies that might otherwise be triggered by taking isolated iron supplements.

Interactions with Medicines

Certain medicines interact with this supplement.

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Aspirin

    Gastrointestinal (GI) bleeding is a common side effect of taking aspirin. A person with aspirin-induced GI bleeding may not always have symptoms (like stomach pain) or obvious signs of blood in their stool. Such bleeding causes loss of iron from the body. Long-term blood loss due to regular use of aspirin can lead to iron-deficiency anemia . Lost iron can be replaced with iron supplements. Iron supplementation should be used only in cases of iron deficiency verified with laboratory tests.

  • Cimetidine

    Stomach acid may facilitate iron absorption. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption.73 People with ulcers may also be iron deficient due to blood loss and benefit from iron supplementation. Iron levels in the blood can be checked with lab tests.

  • Dipyridamole

    Some studies suggest the taking of too much iron by individuals who are not iron deficient can result in tissue damage that may contribute to heart disease.74 Test tube studies have shown dipyridamole blocks platelet clumping caused by iron,75 which might reduce the damage caused by this mineral. Controlled human studies are needed to test this possibility.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Etodolac

    NSAIDs cause gastrointestinal (GI) irritation, bleeding, and iron loss.77 Iron supplements can cause GI irritation.78 However, iron supplementation is sometimes needed in people taking NSAIDs if those drugs have caused enough blood loss to lead to iron deficiency . If both iron and etodolac are prescribed, they should be taken with food to reduce GI irritation and bleeding risk.

  • Famotidine

    Stomach acid may increase absorption of iron from food. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption.79 The iron found in supplements is available to the body without the need for stomach acid. People with ulcers may be iron deficient due to blood loss. If iron deficiency is present, iron supplementation may be beneficial. Iron levels in the blood can be checked with lab tests.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Haloperidol

    Haloperidol may cause decreased blood levels of iron.81 The importance of this interaction remains unclear. Iron should not be supplemented unless a deficiency is diagnosed.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Hyoscyamine

    Absorption of ferrous citrate, an iron compound that is usually well absorbed, is reduced in individuals taking hyoscyamine;82 therefore, these two substances should not be taken at the same time.

  • Ibuprofen

    NSAIDs cause gastrointestinal (GI) irritation, bleeding, and iron loss.83 Iron supplements can cause GI irritation.84 However, iron supplementation is sometimes needed in people taking NSAIDs if those drugs have caused enough blood loss to lead to iron deficiency . If both iron and ibuprofen are prescribed, they should be taken with food to reduce GI irritation and bleeding risk.

  • Magnesium Hydroxide

    Antacids, including magnesium hydroxide, may reduce the absorption of dietary iron. Iron supplements do not require stomach acid for absorption and one human study found that a magnesium hydroxide/ aluminum hydroxide antacid did not decrease supplemental iron absorption.86

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Nabumetone

    NSAIDs cause gastrointestinal (GI) irritation, bleeding, and iron loss.88 Iron supplements can cause GI irritation.89 However, iron supplementation is sometimes needed in people taking NSAIDs if those drugs have caused enough blood loss to lead to iron deficiency . If both iron and nabumetone are prescribed, they should be taken with food to reduce GI irritation and bleeding risk.

  • Naproxen

    NSAIDs cause gastrointestinal (GI) irritation, bleeding, and iron loss.90 Iron supplements can cause GI irritation.91 However, iron supplementation is sometimes needed in people taking NSAIDs if those drugs have caused enough blood loss to lead to iron deficiency . If both iron and naproxen are prescribed, they should be taken with food to reduce GI irritation and bleeding risk.

  • Neomycin

    Neomycin can decrease absorption or increase elimination of many nutrients, including calcium , carbohydrates, beta-carotene , fats, folic acid , iron , magnesium , potassium , sodium, and vitamin A , vitamin B12 , vitamin D , and vitamin K .92 , 93 Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.

  • Nizatidine

    Stomach acid may increase absorption of iron from food. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption.94 The iron found in supplements is available to the body without the need for stomach acid. People with ulcers may be iron deficient due to blood loss. If iron deficiency is present, iron supplementation may be beneficial. Iron levels in the blood can be checked with lab tests.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Oxaprozin

    NSAIDs cause gastrointestinal (GI) irritation, bleeding, and iron loss.95 Iron supplements can cause GI irritation.96 However, iron supplementation is sometimes needed in people taking NSAIDs if those drugs have caused enough blood loss to lead to iron deficiency . If both iron and oxaprozin are prescribed, they should be taken with food to reduce GI irritation and bleeding risk.

  • Ranitidine

    Stomach acid may facilitate iron absorption. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption.100 People with ulcers may also be iron deficient due to blood loss and benefit from iron supplementation. Iron levels in the blood can be checked with lab tests.

  • Sodium Bicarbonate

    In a study of nine healthy people, sodium bicarbonate administered with 10 mg of iron led to lower iron levels compared to iron administered alone.101 This interaction may be avoided by taking sodium bicarbonate-containing products two hours before or after iron-containing supplements.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Stanozolol

    Stanozolol was associated with iron depletion in a group of 16 people.102 The results suggest that people taking this drug on a regular basis have their iron status monitored by the prescribing doctor. There is insufficient information to recommend routine iron supplementation during stanozolol treatment.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Reduce Side Effects

  • Amlodipine-Benazepril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.71

  • Benazepril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.72

  • Enalapril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.76

  • Fosinopril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.80

  • Lisinopril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.85

  • Moexipril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.87

  • Perindopril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.97

  • Quinapril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.98

  • Ramipril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.99

  • Trandolapril

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.103

Support Medicine

  • none

Reduces Effectiveness

  • Carbidopa

    Iron supplements taken with carbidopa may interfere with the action of the drug.104

  • Carbidopa-Levodopa

    Iron supplements taken with carbidopa interfere with the action of the drug.105 People taking carbidopa should not supplement iron without consulting the prescribing physician.

  • Ciprofloxacin

    Minerals such as aluminum, calcium , copper , iron , magnesium , manganese , and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.106 , 107 , 108 , 109 Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.110

  • Demeclocycline

    Taking mineral supplements or antacids that contain aluminum, calcium , iron , magnesium , or zinc at the same time as tetracyclines inhibits the absorption of the drug.111 Therefore, individuals should take tetracyclines at least two hours before or after products containing minerals.

  • Doxycycline

    Many minerals can decrease the absorption and reduce effectiveness of doxycycline, including calcium , magnesium , iron , zinc , and others.112 To avoid these interactions, doxycycline should be taken two hours before or two hours after dairy products (high in calcium) and mineral-containing antacids or supplements.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Gemifloxacin

    A review of interactions involving quinolone antibiotics indicated that supplements containing iron, when taken at the same time as gemifloxacin, might reduce absorption of the drug up to 50%.113 Consequently, gemifloxacin and supplements containing iron should not be taken at the same time.

  • Levofloxacin

    Taking iron supplements concomitantly with levofloxacin can reduce the absorption—and thus the effectiveness—of the drug.114 Therefore, nutritional supplements containing iron, if used, should be taken two hours before or after taking levofloxacin.

  • Methyldopa

    Iron supplements have been found to decrease methyldopa absorption.115 , 116 Taking methyldopa two hours before or after iron-containing products can help avoid this interaction.

  • Ofloxacin

    Minerals including calcium , iron , magnesium , and zinc can bind to fluoroquinolones, including ofloxacin, greatly reducing drug absorption.117 Ofloxacin should be taken four hours before or two hours after consuming antacids (Maalox®, Mylanta®, Tumms®, Rolaids® and others) that may contain these minerals and mineral-containing supplements .118

  • Penicillamine

    Penicillamine binds iron. When taken with iron, penicillamine absorption and activity are reduced.119 Four cases of penicillamine-induced kidney damage were reported when concomitant iron therapy was stopped, which presumably led to the increased penicillamine absorption and toxicity.120

  • Risedronate

    Taking risedronate at the same time as iron , zinc , or magnesium may reduce the amount of drug absorbed.121 Therefore, people taking risedronate who wish to supplement with these minerals should take them an hour before or two hours after the drug.

  • Sulfasalazine

    Iron can bind with sulfasalazine, decreasing sulfasalazine absorption and possibly decreasing iron absorption.122 This interaction can be minimized by taking iron-containing products two hours before or after sulfasalazine.

  • Tetracycline

    Many minerals can decrease the absorption of tetracycline, thus reducing its effectiveness. These minerals include aluminum (in antacids), calcium (in antacids, dairy products, and supplements), magnesium (in antacids and supplements), iron (in food and supplements), zinc (in food and supplements), and others.

  • Warfarin

    Iron , magnesium , and zinc may bind with warfarin, potentially decreasing their absorption and activity.123 People on warfarin therapy should take warfarin and iron/magnesium/zinc-containing products at least two hours apart.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Potential Negative Interaction

  • Deferoxamine

    People treated with deferoxamine for dangerously high levels of iron should not take iron supplements, because iron exacerbates their condition, further increasing the need for the deferoxamine. They should read all labels carefully for iron content. All people treated with deferoxamine should consult their prescribing doctor before using any iron-containing products.

Explanation Required

  • Captopril

    Iron may interfere with captopril absorption. They should not be taken within two hours of each other.124

    In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor, supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks reduced the severity of the cough by a statistically significant 45%, compared with a nonsignificant 8% improvement in the placebo group.125

  • Desogestrel-Ethinyl Estradiol

    Menstrual blood loss is typically reduced with use of oral contraceptives. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.126 Premenopausal women taking oral contraceptives should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Dessicated Thyroid

    Iron deficiency has been reported to impair the body’s ability to make its own thyroid hormones,127 which could increase the need for thyroid medication. In a preliminary trial, iron supplementation given to iron-deficient women with low blood levels of thyroid hormones, partially normalized these levels.128 Diagnosing iron deficiency requires the help of a doctor. The body’s ability to make its own thyroid hormones is also reduced during low-calorie dieting. Iron supplementation (27 mg per day) was reported in a controlled study to help maintain normal thyroid hormone levels in obese patients despite a very low-calorie diet.129

    However, iron supplements may decrease absorption of thyroid hormone medications.130 , 131 People taking thyroid hormone medications should talk with their doctor before taking iron-containing products. If advised to supplement, iron and the drug should not be taken within less than four hours of each other.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Ethinyl Estradiol and Levonorgestrel

    Menstrual blood loss is typically reduced with use of oral contraceptives. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.132 Premenopausal women taking oral contraceptives should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Ethinyl Estradiol and Norethindrone

    Menstrual blood loss is typically reduced with use of OCs. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.133 Premenopausal women taking OCs should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Ethinyl Estradiol and Norgestimate

    Menstrual blood loss is typically reduced with use of OCs. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.134 Premenopausal women taking OCs should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Ethinyl Estradiol and Norgestrel

    Menstrual blood loss is typically reduced with use of oral contraceptives. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.135 Premenopausal women taking oral contraceptives should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Indomethacin

    Iron supplements can cause stomach irritation. Use of iron supplements with indomethacin increases the risk of stomach irritation and bleeding.136 However, stomach bleeding causes iron loss. If both iron and indomethacin are prescribed, they should be taken with food to reduce stomach irritation and bleeding risk.

  • Levonorgestrel

    Menstrual blood loss is typically reduced with use of oral contraceptives. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.137 Premenopausal women taking oral contraceptives should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Levonorgestrel-Ethinyl Estrad

    Menstrual blood loss is typically reduced with use of oral contraceptives. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.138 Premenopausal women taking oral contraceptives should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Levothyroxine

    Iron deficiency has been reported to impair the body’s ability to make its own thyroid hormones,139 which could increase the need for thyroid medication. In a preliminary trial, iron supplementation given to iron-deficient women with low blood levels of thyroid hormones, partially normalized these levels.140 Diagnosing iron deficiency requires the help of a doctor. The body’s ability to make its own thyroid hormones is also reduced during low-calorie dieting. Iron supplementation (27 mg per day) was reported in a controlled study to help maintain normal thyroid hormone levels in obese patients despite a very low-calorie diet.141

    However, iron supplements may decrease absorption of thyroid hormone medications.142 , 143 People taking thyroid hormone medications should talk with their doctor before taking iron-containing products.  If advised to supplement, iron and the drug should not be taken within less than four hours of each other.

  • Liothyronine

    Iron deficiency has been reported to impair the body’s ability to make its own thyroid hormones,144 which could increase the need for thyroid medication. In a preliminary trial, iron supplementation given to iron-deficient women with low blood levels of thyroid hormones, partially normalized these levels.145 Diagnosing iron deficiency requires the help of a doctor. The body’s ability to make its own thyroid hormones is also reduced during low-calorie dieting. Iron supplementation (27 mg per day) was reported in a controlled study to help maintain normal thyroid hormone levels in obese patients despite a very low-calorie diet.146

    However, iron supplements may decrease absorption of thyroid hormone medications.147 , 148 People taking thyroid hormone medications should talk with their doctor before taking iron-containing products. If advised to supplement, iron and the drug should not be taken within less than four hours of each other.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Liotrix

    Iron deficiency has been reported to impair the body’s ability to make its own thyroid hormones,149 which could increase the need for thyroid medication. In a preliminary trial, iron supplementation given to iron-deficient women with low blood levels of thyroid hormones, partially normalized these levels.150 Diagnosing iron deficiency requires the help of a doctor. The body’s ability to make its own thyroid hormones is also reduced during low-calorie dieting. Iron supplementation (27 mg per day) was reported in a controlled study to help maintain normal thyroid hormone levels in obese patients despite a very low-calorie diet.151

    However, iron supplements may decrease absorption of thyroid hormone medications.152 , 153 People taking thyroid hormone medications should talk with their doctor before taking iron-containing products. If advised to supplement, iron and the drug should not be taken within less than four hours of each other.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Mestranol and Norethindrone

    Menstrual blood loss is typically reduced with use of oral contraceptives. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.154 Premenopausal women taking oral contraceptives should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

  • Minocycline

    Taking calcium, iron, magnesium, or zinc at the same time as minocycline can decrease the absorption of both the drug155 , 156 and the mineral. Therefore, calcium, iron, magnesium, or zinc supplements, if used, should be taken an hour before or after the drug.

  • Norgestimate-Ethinyl Estradiol

    Menstrual blood loss is typically reduced with use of OCs. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.157 Premenopausal women taking OCs should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

More Resources

Iron

Where to Find It

The most absorbable form of iron, called “heme” iron, is found in oysters, meat and poultry, and fish. Non-heme iron is also found in these foods, as well as in dried fruit, molasses, leafy green vegetables, wine, and iron supplements. Acidic foods (such as tomato sauce) cooked in an iron pan can also be a source of dietary iron.

Resources

See a list of books, periodicals, and other resources for this and related topics.

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