Is Vitamin B12 Deficiency a Risk Factor for Cardiovascular Disease in Vegetarians?

The goal of this paper is to describe the role of vitamin B-12 deficiency in cardiovascular disease development among vegetarians. Vegetarians have a high prevalence of vitamin B-12 deficiency. Deficiency of this vitamin is associated with a variety of atherogenic processes that are mainly, but not exclusively, due to vitamin B-12 deficiency-induced hyperhomocysteinemia. Each 5-mu mol/L increase above 10 mu mol/L of serum homocysteine is associated with a 20% increased risk of circulatory health problems. Mean homocysteine concentration 410 mu mol/L among vegetarians was reported in 32 of 34 reports. Macrocytosis associated with vitamin B-12 deficiency is also associated with fatal and non-fatal coronary disease, myocardial infarction, stroke, and other circulatory health problems. Compared with non-vegetarians, vegetarians have an improved profile of the traditional cardiovascular disease risk factors, including serum lipids, blood pressure, serum glucose concentration, and weight status. However, not all studies that assessed cardiovascular disease incidence among vegetarians reported a protective effect. Among studies that did show a lower prevalence of circulatory health problems, the effect was not as pronounced as expected, which may be a result of poor vitamin B-12 status due to a vegetarian diet. Vitamin B-12 deficiency may negate the cardiovascular disease prevention benefits of vegetarian diets. In order to further reduce the risk of cardiovascular disease, vegetarians should be advised to use vitamin B-12 supplements. (C) 2015 American Journal of Preventive Medicine