The modifying effect of vitamin C on the association between perfluorinated compounds and insulin resistance in the Korean elderly: a double-blind, randomized, placebo-controlled crossover trial.
OBJECTIVE
There is limited evidence whether environmental exposure to perfluorinated compounds (PFCs) affects insulin resistance (IR) and whether vitamin C intake protects against the adverse effect of PFCs. This study was carried out to investigate the effect of PFCs on IR through oxidative stress, and the effects of a 4-week consumption of vitamin C supplement compared placebo on development of IR by PFCs.


METHODS
For a double-blind, community-based, randomized, placebo-controlled crossover intervention of vitamin C, we assigned 141 elderly subjects to both vitamin C and placebo treatments for 4 weeks. We measured serum levels of PFCs to estimate PFC exposures and urinary levels of malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (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
Perfluorooctane sulfonate (PFOS) and perfluorododecanoic acid (PFDoDA) levels were found to be positively associated with HOMA index at the baseline and after placebo treatment. Risks of IR for the top decile of PFOS and PFDoDA exposures were significantly elevated compared with those with lower PFOS and PFDoDA exposures (both, P < 0.0001). However, the effects of PFOS and PFDoDA on HOMA disappeared after vitamin C supplementation (both, P > 0.30). Furthermore, PFOS and PFDoDA levels were also significantly associated with MDA and 8-OHdG levels, and MDA levels were positively associated with HOMA index.


CONCLUSIONS
PFOS and PFDoDA exposures were positively associated with IR and oxidative stress, and vitamin C supplementation protected against the adverse effects of PFOS and PFDoDA on IR.
Department of Environmental Health, Graduate School of Public Health, Seoul National University, Seoul, Republic of Korea.
Jin Hee
JH
Kim
Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea.
Hye Yin
HY
Park
Department of Health, Environment and Safety, Eulji University, Sungnam, Republic of Korea.
Jung Dae
JD
Jeon
Department of Health, Environment and Safety, Eulji University, Sungnam, Republic of Korea.
Younglim
Y
Kho
Department of Marine Science, College of Natural Sciences, University of Incheon, Incheon, Republic of Korea.
Seung-Kyu
SK
Kim
Department of Family Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
Min-Seon
MS
Park
Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea. ychong1@snu.ac.kr.|Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea. ychong1@snu.ac.kr.
Yun-Chul
YC
Hong
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000368:Aged; D000369:Aged, 80 and over; D001205:Ascorbic Acid / Q000008:administration & dosage*; D044466:Asian People; D015415:Biomarkers / Q000652:urine; D001786:Blood Glucose / Q000378:metabolism; D002210:Caprylates / Q000633:toxicity*; D003367:Cotinine / Q000652:urine; D003404:Creatinine / Q000652:urine; D018592:Cross-Over Studies; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000652:urine; D019587:Dietary Supplements; D004311:Double-Blind Method; D005466:Fluorocarbons / Q000633:toxicity*; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008315:Malondialdehyde / Q000652:urine; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects; D056910:Republic of Korea
D015415:Biomarkers; D001786:Blood Glucose; D002210:Caprylates; D005466:Fluorocarbons; D007328:Insulin; D008315:Malondialdehyde; D000080242:8-Hydroxy-2'-Deoxyguanosine; C023036:perfluorooctanoic acid; D003404:Creatinine; D003849:Deoxyguanosine; D003367:Cotinine; D001205:Ascorbic Acid
Insulin resistance; Oxidative stress; Perfluorinated compounds; Vitamin C supplementation