Effects of a long-term vegetarian diet on biomarkers of antioxidant status and cardiovascular disease risk.

OBJECTIVE: We compared plasma biomarkers of antioxidant status, oxidative stress, inflammation, and risk for coronary heart disease in long-term vegetarians and age- and sex-matched omnivores.

METHODS: Thirty vegetarians (mean age +/- standard deviation: 44.2 +/- 9.0 y) were recruited. The subjects had been vegetarian for 5 to 55 y (21.8 +/- 12.2 y). The control group comprised 30 adults selected by age-stratified sampling from a community health project (mean age: 44.0 +/- 9.2 y). Fasting plasma total antioxidant status (ferric-reducing antioxidant power), ascorbic acid (AA), alpha-tocopherol (total and lipid standardized), malondialdehyde, total cholesterol, triacylglycerol, uric acid (UA), and high-sensitivity C-reactive protein (hsCRP) were measured.

RESULTS: Plasma AA was significantly higher in the vegetarians than in the omnivores (90.5 +/- 21.0 and 61.8 +/- 17.0 microM; P < 0.001). The vegetarians had lower concentrations of triacylglycerol, UA, and hsCRP. Plasma total and lipid-standardized alpha-tocopherol concentrations were also lower in the vegetarians: 22.0 +/- 5.9 and 27.0 +/- 7.9 microM versus 3.76 +/- 0.57 and 4.23 +/- 0.58 microM per millimoles per liter of total cholesterol plus triacylglycerol, respectively. There was a significant inverse correlation between AA and UA (r = -0.343, P < 0.01; n = 60) and between AA and hsCRP (r = -0.306, P < 0.05; n = 55). Plasma ferric-reducing antioxidant power and malondialdehyde did not differ significantly between groups; however, the contribution of AA to the total antioxidant capacity of plasma was approximately 50% greater in the vegetarians.

CONCLUSIONS: A long-term vegetarian diet is associated with markedly higher fasting plasma AA concentrations and lower concentrations of TAG, UA, and hsCRP. Long-term vegetarians have a better antioxidant status and coronary heart disease risk profile than do apparently healthy omnivores. Plasma AA may act a useful marker of overall health status.