Vitamin B12 and D status in long-term vegetarians: Impact of diet duration and subtypes in Beijing, China.

This study reveals a dual challenge among Beijing long-term vegetarians: vitamin B12 deficiency was strongly associated with the degree of exclusion of animal products from the diet (veganism), while vitamin D deficiency was highly prevalent and worsened with longer diet duration. The near-universal vitamin D deficiency observed in this study suggests that, in the Beijing context, the risk may extend beyond dietary choice, potentially reflecting regional environmental factors; however, this requires confirmation through comparative studies with omnivores controls.