Effect of supplementation with B vitamins and antioxidants on levels of asymmetric dimethylarginine (ADMA) and C-reactive protein (CRP): a double-blind, randomised, factorial design, placebo-controlled trial

Purpose
Cardiovascular risk factors such as elevated levels of asymmetric dimethylarginine (ADMA)/C-reactive protein (CRP) and homocysteine are potentially related to essential micronutrients such as certain B vitamins and antioxidant vitamins. The aim of the present study was to investigate whether supplementation with moderate doses of B vitamins and/or antioxidants could alter either ADMA and/or CRP concentrations in middle-aged, apparently healthy men with mildly elevated homocysteine levels.

Methods
A randomised, double-blind, factorial design, intervention study was carried out on 132 men with mildly elevated homocysteine levels, allocated to four groups (a) B vitamins alone—1 mg folic acid, 7.2 mg pyridoxine, 0.02 mg cyanocobalamin daily, (b) antioxidants alone—150 mg ascorbic acid, 67 mg vitamin E, 9 mg β-carotene daily, (c) B vitamins with antioxidant vitamins, or (d) placebo. A total of 101 men completed the study to 8 weeks.

Results
When the percentage of baseline ADMA and CRP was examined at 8 weeks, no statistically significant differences were observed between the four groups (p = 0.21 and p = 0.90, respectively). Similar non-significant results were observed when analysis was stratified based on baseline CRP levels ( < 1.0 mg/L, p = 0.10; ≥1.0 mg/L, p = 0.64) and smoking status (all p ≥ 0.05).

Conclusions
Supplementation with moderate doses of B vitamins and/or antioxidants did not alter either ADMA or CRP concentrations in these middle-aged, apparently healthy men with mildly elevated homocysteine levels.