One of the goals of this site is to shed light on key nutritional-related questions and misconceptions about veganism and the supposed health risks associated with it. Iron deficiency and anemia are another touchy subject that needs to be clarified, and I have pulled out information from different sources to give you a full, comprehensive, and summarized overview on the subject.
I decided I need to present this information here, because recently I discussed my diet with a carnivorous friend, when she mentioned that she was found anemic although she regularly consumes meat. On the other hand, my mother developed severe anemia years ago when she first stopped eating meat.
So, does a vegan diet significantly increase the risk of anemia and iron deficiency?
Instead of trying to come up with a short straightforward answer, let’s first understand what it all means.
Let us start with the fact that there are different types of anemia. Here are the most common ones:
Iron deficiency anemia
This is the most common type of anemia worldwide. Iron deficiency anemia is caused by a shortage of iron in your body. Your bone marrow needs iron to make hemoglobin. Without adequate iron, your body can’t produce enough hemoglobin for red blood cells.
Without iron supplementation, this type of anemia occurs in many pregnant women. It is also caused by blood loss, such as from heavy menstrual bleeding, an ulcer, cancer and regular use of some over-the-counter pain relievers, especially aspirin.
Vitamin deficiency anemia
In addition to iron, your body needs folate and vitamin B-12 to produce enough healthy red blood cells. A diet lacking in these and other key nutrients can cause decreased red blood cell production.
Additionally, some people may consume enough B-12, but their bodies aren’t able to process the vitamin. This can lead to vitamin deficiency anemia, also known as pernicious anemia.
Anemia of chronic disease
Certain diseases — such as cancer, HIV/AIDS, rheumatoid arthritis, kidney disease, Crohn’s disease and other chronic inflammatory diseases — can interfere with the production of red blood cells.
Iron is prevalent in a wide variety of plant foods, especially beans and grains. In fact, vegans’ iron intakes are as high or higher than non-vegetarians.
The key word here is ‘heme’. Iron is found in food in two forms, heme and non-heme iron. Heme iron, which makes up 40 percent of the iron in meat, poultry, and fish, is well absorbed. Non-heme iron, 60 percent of the iron in animal tissue and all the iron in plants (fruits, vegetables, grains, nuts) is less well absorbed. Non-heme iron requires being released from food components by hydrochloric acid and the digestive enzyme pepsin in the stomach. Non-heme iron needs to be shuttled from the digestive tract into the bloodstream by a protein called transferrin.
Because vegan diets only contain non-heme iron, vegans should be especially aware of foods that are high in iron and techniques that can promote iron absorption. Recommendations for iron for vegetarians (including vegans) may be as much as 1.8 times higher than for non-vegetarians (1).
Some might expect that since the vegan diet contains a form of iron that is not that well absorbed, vegans might be prone to developing iron deficiency anemia.
However, surveys of vegans (2,3) have found that iron deficiency anemia is no more common among vegetarians than among the general population although vegans tend to have lower iron stores (3).
Another reason for the satisfactory iron status of vegans is that vegan diets are high in vitamin C.
Vitamin C acts to markedly increase absorption of non-heme iron. Adding a vitamin C source to a meal increases non-heme iron absorption up to six-fold which makes the absorption of non-heme iron as good or better than that of heme iron (4).
Fortunately, many vegetables, such as broccoli and bok choy, which are high in iron, are also high in vitamin C so that the iron in these foods is very well absorbed. Commonly eaten combinations, such as beans and tomato sauce or stir-fried tofu and broccoli, also result in generous levels of iron absorption.
Ironically, foods such as dairy hinder iron absorption in the body. Calcium supplements can also inhibit iron absorption if taken with meals.
Polyphenols, which include tannic acid, can inhibit iron absorption, and are found in coffee, cocoa, and black, green and many herbal teas. You should avoid these foods at meals if you are trying to increase iron absorption (5). Tea, coffee, and calcium supplements should be used several hours before a meal that is high in iron. One study showed that, over four weeks, green and black tea lowered iron levels primarily in people with serum ferritin levels less than 20 µg/l (6).
It must also be noted that there are many other risk factors related to anemia that have nothing to do with your vegan diet:
Intestinal disorders. Having an intestinal disorder that affects the absorption of nutrients in your small intestine — such as Crohn’s disease and celiac disease — puts you at risk of anemia.
Menstruation. In general, women who haven’t experienced menopause have a greater risk of iron deficiency anemia than do men and postmenopausal women. That’s because menstruation causes the loss of red blood cells.
Pregnancy. If you’re pregnant and aren’t taking a multivitamin with folic acid, you’re at an increased risk of anemia.
Chronic conditions. If you have cancer, kidney failure or another chronic condition, you may be at risk of anemia of chronic disease. These conditions can lead to a shortage of red blood cells.
Slow, chronic blood loss from an ulcer or other source within your body can deplete your body’s store of iron, leading to iron deficiency anemia.
Family history. If your family has a history of an inherited anemia, such as sickle cell anemia, you also may be at increased risk of the condition.
Other factors. A history of certain infections, blood diseases and autoimmune disorders, alcoholism, exposure to toxic chemicals, and the use of some medications can affect red blood cell production and lead to anemia.
Age. People over age 65 are at increased risk of anemia.
So, should you be diagnosed with anemia, don’t immediately assume it is just because of your diet as a vegan! Please have yourself checked out for other physical causes first.
If you are a woman, you could be anemic simply because of heavy menstruation, fibroids, or other female problems. And vegans of both sexes should be checked to rule out other causes such as ulcers, kidney disease, and cancer. Keep in mind there are also less scary causes of anemia … such as being a blood donor or an athlete, or just regularly doing intense exercise.
You do not need to worry about iron if you are otherwise healthy and eat a varied vegetarian or vegan diet. If you think your iron stores might be low, you can increase iron absorption by:
Cooking foods (especially water based acidic foods like tomato sauce) in cast iron skillets.
If your concerns persist, you should have a doctor measure your iron status. It is important for any vegan with iron deficiency to correct it because during iron deficiency, the body has a tendency to absorb too much manganese. Luckily, vitamin C increases iron absorption but does not increase manganese absorption.
Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2001.
Haddad EH, Berk LS, Kettering JD, Hubbard RW, Peters WR. Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr 1999;70(suppl):586S-93S.
Obeid R, Geisel J, Schorr H, et al. The impact of vegetarianism on some haematological parameters. Eur J Haematol. 2002;69:275-9.
Hallberg L. Bioavailability of dietary iron in man. Ann Rev Nutr 1981;1:123-147.
Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999 Apr;81(4):289-95. PubMed PMID: 10999016.
Schlesier K, Kühn B, Kiehntopf M, Winnefeld K, Roskos M, Bitsch R, Böhm V. Comparative evaluation of green and black tea consumption on the iron status of omnivorous and vegetarian people. Food Research International. 2012 May;46(2):522-27.
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