Serum Carotenoids Are Inversely Associated with RBP4 and Other Inflammatory Markers in Middle-Aged and Elderly Adults

(1) Background: Carotenoids may be inversely associated with inflammatory markers (i.e., TNF-α, IL-6, IL-1β). However, data are scarce on retinol binding protein 4 (RBP4) in humans. We examined the associations among serum carotenoids, RBP4 and several inflammatory markers in a Chinese population. (2) Methods: This community-based cross-sectional study included 3031 participants (68% males) aged 40-75 years in Guangzhou, China. Serum concentrations of carotenoids, RBP4, and inflammatory markers were measured. (3) Results: Generally, serum individual and total carotenoids were significantly and inversely associated with retinol-adjusted RBP4, RBP4, hsCRP, MCP1, and TNF-alpha levels. Age- and gender-adjusted partial correlation coefficients between total carotenoids and the above inflammatory markers were -0.129, -0.097, -0.159, -0.079, and -0.014 (all p < 0.01, except for TNF-alpha with p >0.05), respectively. The multivariate-adjusted values of partial correlation coefficients for these inflammation-related markers were -0.098, -0.079, -0.114, -0.090, and -0.079 (all p < 0.01), respectively. Among the individual carotenoids, those with the most predominant association were lutein-zeaxanthin and total carotenoids for retinol-adjusted RBP4 and RBP4, alpha- and beta-carotene for hsCRP, and alpha-carotene for MCP1 and TNF-alpha. No significant associations were observed for IL-6 and IL-1beta. (4) Conclusions: Serum carotenoids were inversely associated with RBP4, hsCRP, MCP1 and TNF-alpha among middle-aged and elderly Chinese adults.