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

BACKGROUND AND OBJECTIVES: This study aimed to evaluate vitamin B12 and D levels among long-term vegetarians and to assess the influence of their diet duration and diet subtypes on nutritional status in Beijing, China. METHODS AND STUDY DESIGN: A cross-sectional analysis was conducted on 104 vegetarians (84 vegans, 20 lacto-ovo vegetarians). Serum vitamin B12 and D levels were measured, and demographic, dietary, and supplement use data were collected. Statistical analyses included ANOVA, Kruskal-Wallis tests, chi-square tests, and multivariate regressions. RESULTS: The prevalence of vitamin B12 deficiency ( CONCLUSIONS: 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.