Effect of a vegetarian diets on the vitamin B status and homocysteine levels in elderly Taiwanese

To investigate the effects of a vegetarian diets on the vitamin B status and homocysteine (Hcy) levels in elderly Taiwanese, we analyzed plasma folate and Hcy levels in 47 vegetarians, 314 occasional vegetarians and 1056 non-vegetarians aged ≥ 65 years, sampled from the Elderly Nutrition and Health Survey in Taiwan (1999-2000) (Elderly NAHSIT). Results showed that the average plasma Hcy levels of vegetarians (14.3 ± 0.6 μmol/L) were significantly higher than those of occasional vegetarians (12.5 ± 0.3 μmol/L) and non-vegetarians (12.3 ± 0.1 μmol/L). The vegetarians had significantly higher levels of plasma folate (13.1 ± 0.8 ng/mL) than the occasional vegetarians (11.1 ± 0.3 ng/mL) and non-vegetarians (11.4 ± 0.2 ng/mL), and a better vitamin B₂ status assessed by the levels of the erythrocyte glutathione reductase activity coefficient (EGRAC, 1.00 ± 0.02), but lower levels of serum vitamin B₁₂ (381 ± 36 pmol/L). There were significantly higher prevalences of vitamin B₁₂ insufficiency and hyperhomocysteinemia (Hcy > 15 μmol/L), but lower prevalences of vitamin B₂ or B₆ insufficiency in the vegetarians group than those in occasional vegetarians and non-vegetarians groups. After adjusting for several effect factors, the plasma Hcy levels in the elderly with a vitamin B₁₂ insufficiency were significantly higher in vegetarians than those in occasional vegetarians and non-vegetarians, but in those with folate, vitamin B₂ or B₆ insufficiency did not significantly differ among the three diet groups. Therefore, maintaining a good vitamin B₁₂ status should be emphasized for vegetarian subjects to avoid elevated Hcy levels. In addition, occasional vegetarians had the lowest prevalences of hyperhomocysteinemia and lower prevalences of vitamin B ₂ or B₁₂ insufficiency compared to non-vegetarians, suggesting that further study may be worth while to investigate whether an occasional vegetarian diet is more beneficial for the elderly.