How prevalent is vitamin B12 deficiency among vegetarians?


  • Affiliations: R Pawlak is with the Department of Nutrition Science, East Carolina University, North Carolina, USA. SJ Parrott is with the Department of Nutritional Sciences, School of Health Related Professions, University of Medicine and Dentistry of New Jersey, Newark, New Jersey, USA. S Raj is with the Department of Public Health, Food Studies and Nutrition, Syracuse University, Syracuse, New York, USA. D Cullum-Dugan is with Namaste Nutrition, Watertown, Massachusetts, USA. D Lucus is with the Sutter Medical Foundation, Roseville, California, USA.

Correspondence: R Pawlak, Department of Nutrition Science, East Carolina University, Rivers West 337, Greenville, NC 27858, USA. E-mail: Phone: +1-252-328-2350.


Vegetarians are at risk for vitamin B12 (B12) deficiency due to suboptimal intake. The goal of the present literature review was to assess the rate of B12 depletion and deficiency among vegetarians and vegans. Using a PubMed search to identify relevant publications, 18 articles were found that reported B12 deficiency rates from studies that identified deficiency by measuring methylmalonic acid, holo-transcobalamin II, or both. The deficiency rates reported for specific populations were as follows: 62% among pregnant women, between 25% and almost 86% among children, 21–41% among adolescents, and 11–90% among the elderly. Higher rates of deficiency were reported among vegans compared with vegetarians and among individuals who had adhered to a vegetarian diet since birth compared with those who had adopted such a diet later in life. The main finding of this review is that vegetarians develop B12 depletion or deficiency regardless of demographic characteristics, place of residency, age, or type of vegetarian diet. Vegetarians should thus take preventive measures to ensure adequate intake of this vitamin, including regular consumption of supplements containing B12.