Effect of vegetarian diet on homocysteine levels

Objective: To compare fasting total plasma homocysteine (tHcy) levels in vegans, lacto-ovovegetarians and control subjects, and to evaluate the relationships between tHcy levels and nutritional variables in vegetarians. Methods: The study was conducted on 45 vegetarian subjects: 31 vegans (19 males, 12 females, mean age 45.8 ± 15.8 years); 14 lacto-ovovegetarians (6 males, 8 females, mean age 48.5 ± 14.5 years), and 29 control subjects (19 males, 10 females, mean age 43.4 ± 16.7 years). tHcy was evaluated by high-performance liquid chromatography. Serum vitamin B12 and folate were analyzed by automated chemiluminescence systems. Clinical records, nutritional and anthropometric variables were collected for all vegetarian subjects. Results: tHcy was significantly higher in vegetarian subjects than in controls (23.9 ± 21.3 vs. 11.6 ± 4.9 μmol/l, p < 0.001). The prevalence of hyperhomocysteinemia was higher in vegetarians than in controls (53.3 vs. 10.3%, p < 0.001). Serum vitamin B12 levels were lower in vegetarians than in control subjects (171.2 ± 73.6 vs. 265.0 ± 52.2 pmol/l, p < 0.01; normal range 220-740 pmol/l). In vegetarian subjects, significant inverse correlations were found between tHcy and serum vitamin B12 levels (r = -0.776, p < 0.001) and between tHcy and serum folate levels (r = -0.340, p < 0.05). Positive correlations were found between tHcy and mean red cell volume (r = 0.44, p < 0.01) and between tHcy and fat-free mass (r = 0.36, p < 0.05). Conclusion: Vegetarian subjects presented significantly higher tHcy levels, higher prevalence of hyperhomocysteinemia, and lower serum vitamin B12 levels than controls.