Association between serum levels of carotenoids and serum asymmetric dimethylarginine levels in Japanese subjects

Background: Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelium nitric oxide synthase (NOS). ADMA binds to a substrate-binding site of NOS and then inhibits nitric oxide production from vascular endothelial cells. Elevated ADMA levels are a risk factor for cardiovascular disease. Recently, it was reported that plasma ADMA levels were negatively correlated with vegetable and fruit consumption. The purpose of this study was to examine the association between serum levels of carotenoids and serum ADMA levels in Japanese subjects. Methods: We conducted a cross-sectional study of 470 subjects (203 men and 267 women) who attended a health examination in August 2011. Serum levels of several carotenoids were separately measured by high-performance liquid chromatography. Serum ADMA levels were determined by using an enzyme-linked immunosorbent assay kit. Results: In women, the multivariate-adjusted odds ratios (ORs) of elevated serum ADMA levels were significantly decreased in the highest tertile for β-cryptoxanthin (OR 0.47, 95% CI 0.23-0.95), α-carotene (OR 0.39, 95% CI 0.18-0.79), and β-carotene (OR 0.36, 95% CI 0.17-0.73) compared to the lowest tertile. In men, significantly decreased ORs were observed in the highest tertiles of serum zeaxanthin/lutein (OR 0.23, 95% CI 0.06-0.69) and a-carotene (OR 0.26, 95% CI 0.07-0.82), and in the middle and the highest tertiles of serum β-carotene (OR 0.27, 95% CI 0.09-0.74 and OR 0.20, 95% CI 0.03-0.88, respectively) when the tertile cutoff points of women were extrapolated to men. Conclusions: Higher serum levels of carotenoids, such as α-carotene and β-carotene, may help to prevent elevated serum ADMA levels in Japanese subjects.