Plasma C-reactive protein (CRP) is an inflammatory biomarker that predicts cardiovascular disease. Lowering elevated CRP with statins has reduced the incidence of cardiovascular disease. We investigated whether vitamin C or E could reduce CRP. Healthy nonsmokers (N = 396) were randomized to three groups, 1000 mg/day vitamin C, 800 IU/day vitamin E, or placebo, for 2 months. Median baseline CRP was low, 0.85 mg/L. No treatment effect was seen when all participants were included. However, a significant interaction was found, indicating that treatment effect depends on baseline CRP concentration. Among participants with CRP indicative of elevated cardiovascular risk (≥ 1.0 mg/L), vitamin C reduced the median CRP by 25.3% vs placebo (p = 0.02) (median reduction in the vitamin C group, 0.25 mg/L, 16.7%). These effects are similar to those of statins. The vitamin E effect was not significant. In summary, treatment with vitamin C but not vitamin E significantly reduced CRP among individuals with CRP ≥ 1.0 mg/L. Among the obese, 75% had CRP ≥ 1.0 mg/L. Research is needed to determine whether reducing this inflammatory biomarker with vitamin C could reduce diseases associated with obesity. But research on clinical benefits of antioxidants should limit participants to persons with elevations in the target biomarkers.
