Unmetabolized folic acid is associated with TNF-α, IL-1β and IL-12 concentrations in a population exposed to mandatory food fortification with folic acid: a cross-sectional population-based study in Sao Paulo, Brazil.

Abstract

The study assessed associations between inflammatory markers, as cytokines, adhesion molecules and unmetabolized folic acid (UMFA) among a population exposed to mandatory fortification. Data were collected from a cross-sectional population-based survey (n = 302) conducted in São Paulo City, Brazil. UMFA was assayed by a modified affinity-HPLC method with electrochemical detection to measure the different forms of the folate in plasma. We used a commercial test kit to analyze cytokines and adhesion molecules. Multiple logistic regressions were applied to investigate the association between inflammatory markers and UMFA. Multiple models were adjusted for sex, age, self-reported skin color, BMI and smoking status. The prevalence of detectable UMFA in this population was high (81.2%), with median concentration of 1.67nmol/L. The odds ratios (95% CIs) for having higher immunological markers levels among individuals in the highest tertile of UMFA were 0.44 (0.24; 0.81) for TNF-α, 0.92 (0.49; 1.75) for CRP, 1.32 (0.70; 2.48) for ICAM, 0.99 (0.54; 1.81) for VCAM, 0.45 (0.25; 0.83) for IL-1β, 0.74 (0.40; 1.38) for IL-6, 1.34 (0.73; 2.44) for IL-8, 0.65 (0.36; 1.18) for IL-10 and 0.49 (0.27; 0.89) for IL-12. UMFA concentrations were inversely associated with elevated proinflammatory markers (TNF-α, IL-1β and IL-12). These results signalize a link between folate metabolism and the inflammatory status of adults in an apparently folate-replete population.