摘要：Background. There are no long-term prospective studies assessing the impact of the vegan diet on vitamin B-12 (B-12) status. Many vegans take B-12 supplements irregularly or refuse to adopt them at all, considering them to be “unnatural” products. The use of B-12 fortifi ed food may be an alternative. Therefore, we aimed to estimate the long-term effect of a vegan diet on serum B-12 concentrations in healthy omnivore adults, comparing the infl uence of natural products consumption and B-12 fortifi ed food.
Material and methods. A fi ve year prospective study was carried out comprising 20 omnivore healthy adult subjects, who moved to strict vegan diet for 5 years. Ten volunteers followed vegan diet based entirely on natural products, while the remaining ten subjects consumed food fortifi ed in B-12. In all subjects serum vitamin B-12 concentration was determined before and 6, 12, 24 and 60 months after the implementation of the diet.
Results. A signifi cant decrease (p < 0.0002) of serum B-12 concentrations in the whole studied group was noted after 60 months of vegan diet. However, observed changes were in fact limited to the subgroup consuming exclusively natural products (p < 0.0001).
Conclusions. Transition from omnivore to vegan diet is associated with the risk of vitamin B-12 defi ciency. B-12 fortifi ed products might constitute a valuable alternative in vegans refusing to take vitamin supplements.
关键词：vegan diet, vitamin B-12, risk of defi ciency, vegetarianism
