Effect of vegetarian diet on homocysteine levels

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.

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 B(12) and folate were analyzed by automated chemiluminescence systems. Clinical records, nutritional and anthropometric variables were collected for all vegetarian subjects.

tHcy was significantly higher in vegetarian subjects than in controls (23.9 +/- 21.3 vs. 11.6 +/- 4.9 micromol/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 B(12) 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 B(12) 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).

Vegetarian subjects presented significantly higher tHcy levels, higher prevalence of hyperhomocysteinemia, and lower serum vitamin B(12) levels than controls.