Vitamin C supplementation protect from adverse effects of perfluorinated compounds on insulin resistance in the elderly: Community-based clinical trial

Abstract

Backgrounds. Perfluorinated compounds (PFCs) are persistent organic pollutants which exhibit hormone disturbances in addition to hepatotoxicity, immunotoxicity, developmental toxicity, and tumorigenic potential. Aims. Whether PFCs affect insulin resistance (IR) and vitamin C intake protects against the adverse effect of PFCs was estimated. Methods. We designed a cross-over intervention study and assigned 141 elderly subjects aged ?60 either to vitamin C or placebo treatment for 4 weeks in a random order. A 2-week washout period was implemented between the interventions. We measured serum levels of PFCs to estimate PFC exposures and urinary levels of MDA and 8-OHdG for oxidative stress. We also measured levels of fasting glucose and insulin and derived the homeostatic model assessment (HOMA) index to assess IR. Results. In 126 participants without a history of diabetes, PFOS and PFDoDA levels were found to be positively associated with HOMA index at the baseline and after placebo treatment (PPFOS=0.053 and PPFDoDA=0.01). Risks of IR determined as HOMA ? 2.5 for the top decile of PFOS and PFDoDA exposures were significantly elevated compared with those of less than top decile exposures (ORPFOS=2.2, PPFOS<0.0001; and ORPFDoDA=3.3, PPFDoDA<0.0001). However, the effects of PFOS and PFDoDA on HOMA were disappeared after vitamin C supplementation. Furthermore, at the baseline and after placebo treatment, PFOS and PFDoDA levels were also significantly associated with MDA (PPFOS=0.02) and 8-OHdG levels (PPFOS=0.001 and PPFDoDA=0.01) and MDA levels were positively associated with HOMA index (P=0.03). Conclusions. In the elderly without a history of diabetes, PFOS and PFDoDA exposures were positively associated with IR and vitamin C supplementation protects against the adverse effect of PFOS and PFDoDA.