Low plasma antioxidants and normal plasma B vitamins and homocysteine in patients with severe obesity.

BACKGROUND: Obesity is among the well-established risk factors for cardiovascular morbidity and mortality. However, the exact mechanisms are not well understood. Low concentrations of vitamins (fat soluble antioxidants and B vitamins) are linked to accelerated atherosclerosis through increased oxidative stress and homocysteine. OBJECTIVE: To compare plasma antioxidant vitamins (carotenoids and vitamin E), B vitamins (folic acid and B12) and homocysteine--all linked to increased cardiovascular morbidity--between patients with severe obesity and lean control subjects. METHODS: We investigated plasma carotenoids, vitamin E, folic acid, B12, and homocysteine in 25 obese patients and their age-matched controls (body mass index 38 +/- 3 vs. 21 +/- 2 kg/m2), respectively), related to BMI and plasma insulin. RESULTS: Patients with obesity had normal B vitamins and a non-significant decrease in plasma homocysteine as compared to controls (9.4 +/- 2.6 vs. 11.4 +/- 4.8 mumol/L, P = 0.07). There was a significant decrease in both plasma carotenoids and vitamin E (0.69 +/- 0.32 vs. 1.25 +/- 0.72 and 24 +/- 10 vs. 33 +/- 14 micrograms/ml, respectively; P < 0.01). Both vitamins were inversely related to BMI and plasma insulin, which was significantly increased in patients with obesity (22 +/- 21 vs. 6 +/- 2 microU/ml, P < 0.01). CONCLUSIONS: Obese patients with BMI above 35 kg/m2 show low plasma antioxidants (carotenoids and vitamin E). This may result in increased oxidative stress and consequently enhanced atherosclerosis in these patients.