The risk of vitamin B12 deficiency is increased for those following vegetarian diets because the primary dietary source of vitamin B12 is animal products; vegetarians, by definition, do not consume meat, so dietary sources of B12 are limited. Vitamin B12 is an essential micronutrient for humans; deficiency results in serious and escalating health problems. To avoid B12 deficiency, a vegetarian diet must include egg, dairy, plant, and algae sources of B12 in their diets; for some, including those following a vegan diet, a B12 supplement is necessary to meet dietary B12 needs.
Vitamin B12 is an Essential Nutrient Required to Maintain a Healthy Life
Fumio Watanabe, in the 2007 article "Vitamin B12 Sources and Biovailability" presented to the Society for Experimental Biology and Medicine,explains that vitamin B12, or the term used to describe all biologically active cobalamins, is synthesized in certain bacteria usually found in the bodies of higher predatory organisms. It is the only vitamin that is synthesized exclusively by microorganisms. According to Ibrahim Elmadfa and Ingrid Singer in the 2009 article “Vitamin B-12 and Homocysteine Status Among Vegetarians: A Global Perspective” in The American Journal of Clinical Nutrition, vitamin B12 plays a fundamental role in cell division and one-carbon metabolism. Critical absorption of B12 occurs in the distal ileum of the intestine where different sources of B12 are absorbed differently by the body; meat sources are absorbed better than egg or plant sources.
Vitamin B12 Deficiency is a Serious Health Risk
Vitamin B12 deficiency is caused by inadequate dietary intake or malabsorption (commonly caused by pernicious anemia). Elmadfa and Singer categorize the symptoms of B12 deficiency into three main categories: anemia, neurologic, and gastrointestinal. These symptoms can include fatigue, appetite loss, and mental health problems like anxiety and depression. Additionally, Asok C. Antony in the article “Vegetarianism and Vitamin B12 (cobalamin) Deficiency” from the American Journal of Clinical Nutrition (2003), found that infants born to mothers who are deficient in vitamin B12 are also at risk for deficiency and suffer long term health problems even after a B12 deficiency has been rectified.
Vegetarians are at a Greater Risk for Vitamin B12 Deficiency
Vegetarians typically obtain vitamin B12 through milk, dairy products, eggs, and “organically-grown” plant sources. According to Antony, plant sources of B12 must have been organically grown in soil that has been fertilized by manure. Additionally, B12 can be obtained through nori (algae), tea leaves, and fortified breakfast cereals.
Meat is the best source of vitamin B12 both because it contains the highest concentration of B12, and the B12 found in meat is the most easily absorbed in the intestine. For vegetarians who do not consume meat, eggs and dairy provide the best source of B12; organically grown leafy vegetables only provide only trace amounts. The recommended daily allowance (RDA) of vitamin B12 is 2.5 mg per day. Vegetarians can consume the required amounts of B12 without the use of a supplement, as long as they are following the "appropriately planned" vegetarian diet as defined by the ADA. However, inadequate B12 consumption requires the use of supplements or fortified breakfast cereals to avoid the health risks of deficiency.
Vegetarians Need to Pay Close Attention to Vitamin B12 Dietary Intake; Supplements May be Necessary
According to Antony, all vegetarians must take a vitamin B12 supplement to maintain health and avoid deficiency. In contrast, most experts do not go as far as to require the use of supplements; however, they universally emphasize a need for careful attention to vitamin B12 dietary intake. To avoid deficiency health risks, individuals following a vegetarian diet must carefully monitor their intake a vitamin B12. For those with inadequate levels of B12, vegans, and expectant mothers, a B12 supplement is recommended to avoid the risks of deficiency
Sources:
Watanabe, F. (2007). “Vitamin B12 sources and bioavailability.” Society for Experimental Biology and Medicine.
Hermann, W. et al. (2001). “Total homocysteine, vitamin B12, and total antioxidant status in vegetarians.” Clinical Chemistry 47(6).
Laura Jayne Parson - Currently pursuing a Master's degree from Westminster College in Education, a writing-intensive porgram. I graduated from the University ...
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