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Deficiencies in iron, as well as vitamin B-12, folate, and even vitamin B-6 can lead to anemia, a condition marked by low levels of red blood cells or low levels of hemoglobin (a protein that carries oxygen) in red blood cells. Supplementing with these nutrients can help prevent or treat the associated anemias.

(Be aware that in people with low blood oxygen levels, severe anemia may affect the accuracy of pulse oximeters readings.)

Anemias and Supplements to Prevent or Treat Them

Low levels of iron can lead to iron-deficiency anemia, a condition that is most common in menstruating women but can also affect children and women who are pregnant. Symptoms of iron deficiency can include fatigue, shortness of breath, rapid or irregular heartbeats, changes in skin and nails, restless legs syndrome, unusual cravings (pica). Supplementing with iron can help prevent and treat this condition. Even in women who are not iron deficient, iron supplementation may help to improve unexplained fatigue. Few men are deficient in iron, and some may be at risk of excess iron. Learn how much and which forms of iron to take for this condition in the ConsumerTips section of the Iron Supplements Review, which also includes information about how to avoid an upset stomach when taking iron. Also see our Top Picks for iron supplements based on our independent tests of quality and comparison of ingredients and cost.

Low levels of vitamin B-12 can cause pernicious anemia (a lack of red blood cells due to inadequate absorption of B-12) which, like iron deficiency anemia, can cause lightheadedness, fatigue, shortness of breath, and rapid heart rate, as well as loss of appetite, diarrhea, tingling or numbness of the hands or feet, paleness or jaundice, unsteadiness when walking and confusion. For those with vitamin B-12 deficiency (which is more common in people lacking intrinsic factor or those with compromised absorption due to gastrointestinal disease or bowel resection), treatment typically consists of vitamin B-12 injections followed by supplementation, although some evidence suggests that vitamin B-12 deficiency can be effectively treated with a high oral dose (1,000 mcg daily) as well. Vitamin B-12 deficiency can also lead to macrocytic anemia (characterized by red blood cells that are abnormally large, unable to function normally, and die earlier than normal).

Folate deficiency can also cause macrocytic anemia and is typically treated by supplementing with 250 to 1,000 mcg of folate (about 420 to 1,700 mcg DFE) per day, although higher doses (1 to 5 mg of folate or 1.7 to 8.5 mg DFE) may be needed in cases of severe deficiency. (See our Top Picks for B-12 supplements based on our independent tests.)

Be aware that folate deficiency has become less common in the U.S. since mandatory folic acid fortification of enriched cereal grain products was initiated, and excessive intake of folate can actually mask a symptom of vitamin B-12 deficiency. (See our Top Picks for folate supplements based on our independent tests.)

Vitamin B-6 deficiency can cause microcytic anemia (characterized by unusually small red blood cells), which is not common in the U.S. but can occur in people with alcohol dependence, impaired kidney function or conditions that cause malabsorption (i.e., celiac disease, Crohn's disease, and ulcerative colitis). In severe cases, vitamin B-6 injections may be needed, but often supplementing with vitamin B-6 or increasing dietary intake of foods with vitamin B-6 is all that is necessary. See our list of Foods Containing B Vitamins to find out which foods are the best source of vitamin B-6 and other B vitamins. (Also, see our Top Picks for B-6 supplements based on our independent tests.)

Beef liver extract, which contains high amounts of these B vitamins and iron, was once commonly used to treat anemia. However, this is no longer a common treatment. Keep in mind that beef liver extract is not the same as desiccated beef liver, a supplement that is promoted as a more concentrated form of the micronutrients found in fresh liver.

Supplements That May Increase the Risk of Anemia

While iron and certain B vitamins can help prevent or treat anemia in people who are deficient in these nutrients, other supplements may actually decrease red blood cell count and increase the risk of anemia. For instance, excessive intake of zinc can interfere with the absorption of copper, which can lead to low red blood cell count. To partially offset these risks, it is generally considered advisable to take copper at a dose of 1 to 3 mg daily when taking zinc supplements long-term.

Excessive intake of turmeric extract may also cause anemia by reducing iron absorption (this is less of a concern with turmeric spice). It would seem prudent for people who are anemic or with marginal iron stores to avoid taking curcumin supplements or to use them at least two to three hours apart from consuming iron-containing meals or supplements.

Supplements that contain high levels of lead may also cause anemia by decreasing the production of hemoglobin and increasing the destruction of red blood cells. For information about which supplements seem to contain highest amounts of lead, see our CL Answer about supplements and health foods that may contain lead.

The herb Gynostemma pentaphyllum (jiaogulan), which is promoted for improving metabolism, increasing energy, treating type 2 diabetes, and increasing weight loss, may also cause mild reduction red blood cell count. It should therefore be used with caution in people who may be anemic or prone to anemia.

Grape seed extract can inhibit iron absorption, and has been shown to decrease iron and ferritin levels in children with excess iron levels. Although there do not appear to be reports of iron deficiency anemia associated with grape seed extract supplementation, to be safe, people at risk for iron deficiency should consult with their physician before taking grape seed extract.

There is mixed evidence as to whether resveratrol inhibits iron absorption, but this is known concern with a popular resveratrol supplement that also contains phytates and quercetin, which may also inhibit iron absorption.

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