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| Iron Deficiency in Vegetarians | | |  Dr. Rashi Sharma
Vegetarianism refers to a dietary pattern where the diet is plant based. However, most people include the consumption of milk and egg products within this definition. Individuals who also exclude egg and dairy products are called vegans.
Meat based diets have been linked to a higher body mass index, increased incidence of hypertension, diabetes, coronary artery disease and some cancers. The Academy of Nutrition and Dietetics endorses the planned vegetarian diet as “healthful and nutritionally adequate” in all stages of life. The advantages appear to be significant. For instance, Leslie Beck, who is a dietitian writing for the Globe and Mail, cites a reduced risk of diabetes by 62 percent, the risk of prostate cancer by 35 percent and so forth.
Today I want to deal specifically with the issue of iron deficiency and compare the impact of these two major dietary choices. I am using a study published in the American Journal of Lifestyle Medicine in 2018. It summarized the findings of 13 articles based on people from ten countries, including the United States, United Kingdom and New Zealand.
Research has shown that iron and vitamin B12 intake are common issues that can develop with dietary restrictions. Iron deficiency can develop from inadequate intake in the diet, impaired absorption in the gastrointestinal tract, or increased losses such as in menstruation or bowel cancer. Iron in meat based diets is often linked to a molecule called heme which is readily absorbed in the digestive system. Iron in plant based foods is bound to molecules such as phytate and oxalate which actually impair absorption. Phytate is one of the more potent inhibitors of iron absorption. It is found in whole grains, legumes and nuts. For these reasons, iron requirements are 1.8 times higher in vegetarians compared to non-vegetarians.
The most widely used marker of body iron stores is called ferritin. However, the cut offs defining low iron stores are not entirely consistent e.g. some studies use cut offs such as 12 micrograms/L whereas others use 25. Nevertheless, the conclusions were consistent. Vegetarians had lower ferritin levels than non-vegetarians. This was true for males as well as females. Iron deficiency was identified in young women as well as mature post menopausal women whether they were meat consumers or vegetarian. The group with the lowest ferritin levels and the highest prevalence of iron deficiency were vegetarian women from UK of Indian descent. As we all know, iron is needed to make red blood cells. If iron deficiency remains untreated, we go on to develop anemia or low blood levels. Red blood cells are needed to carry oxygen to tissues so one can imagine that cell function will be compromised throughout the body. However, it is also important to recognize that iron is needed by other blood cells for proper functioning. For example, white blood cell production will also be impaired. This will lead to impaired immune function and a greater susceptibility to infection.
The study that I cited earlier also found that the vegetarians of all ethnicities had a greater incidence of anemia. Again, anemia was most severe in women from an Indian background.
Governments are taking steps to address this worldwide problem and to mitigate iron deficiency. For example, cereals are often fortified with iron. What can we do to avoid iron deficiency? Cooking plant foods will help release iron from phytates making it easier to absorb. Tea and coffee intake should be delayed 1 or 2 hours following a meal since they contain tannins which also impair iron absorption. Consumption of vitamin C or other organic acids helps iron absorption, so it is helpful to take fruit with meals. Another good way to add iron into the diet is to use cast iron cookware. Cast iron pans offer a nonstick surface which I find useful for over 90 percent of my stove top cooking.
I have already mentioned that anemia impairs the delivery of oxygen to tissues. Some of us may not be aware that iron deficiency without anemia also has clinical consequences. It usually causes non-specific symptoms such as fatigue and unusual food cravings.
A final but extremely important point that I want to make is that iron deficiency in babies and toddlers is associated with impaired cognition and psychomotor development which may be irreversible. Recent studies have shown a prevalence rate or iron deficiency of 30% in US and UK children aged 1-2 years. In spite of such findings, we still do not have clinical guidelines to assess iron deficiency in children in Canada. A Canadian study published December 2019 in CMAJ on-line showed that screening for iron deficiency at age 18 months is cost effective compared to targeted screening.
In conclusion, I support a vegetarian life style but only with careful planning. Special conditions such as pregnancy should probably involve a dietitian. |
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