Interactions between vitamins C and E in human subjects.
Despite convincing in vitro evidence, a vitamin C-E interaction has not been confirmed in vivo. This study was designed to examine the effects of supplementation with either vitamin C or E on their respective plasma concentrations, other antioxidants, lipids and some haemostatic variables. Fasting blood was collected before and after intervention from thirty healthy adults in a double-blinded crossover study. Baselines for measured variables were established after 2 weeks of placebo supplementation, followed by daily supplementation with 73.5 mg RRR-alpha-tocopherol acetate or 500 mg ascorbic acid, and placebo, for 6 weeks. A 2 month washout preceded supplement crossover. Mean values showed that plasma lipid standardised alpha-tocopherol increased with ascorbic acid supplementation: from 4.09 (sem 0.51) to 4.53 (sem 0.66) micromol/mmol total cholesterol plus triacylglycerol (P < 0.05), and plasma ascorbic acid increased from 62.8 (sem 14.9) to 101.3 (sem 22. 2) micromol/l (P < 0.005). Supplementation with (RRR)-alpha-tocopherol acetate increased plasma alpha-tocopherol from 26.8 (sem 3.9) to 32.2 (sem 3.8) micromol/l (P < 0.05), and lipid-standardised alpha-tocopherol from 4.12 (sem 0.48) to 5.38 (sem 0.52) micromol/mmol (P < 0.001). Mean plasma ascorbic acid also increased with vitamin E supplementation, from 64.4 (sem 13.3) to 76. 4 (sem 18.4) micromol/l (P < 0.05). Plasma ferric reducing (antioxidant) power and glutathione peroxidase (U/g haemoglobin) increased in both groups, while urate, total cholesterol and triacylglycerol levels decreased (P < 0.05 throughout). Results are supportive of an in vivo interaction between vitamins C and E.
Hamilton
I M
IM
Northern Ireland Centre for Diet and Health, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
Gilmore
W S
WS
Benzie
I F
IF
Mulholland
C W
CW
Strain
J J
JJ
D000328:Adult; D001205:Ascorbic Acid / Q000378:metabolism*; D002784:Cholesterol / Q000032:analysis; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004347:Drug Interactions; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D005979:Glutathione Peroxidase / Q000032:analysis; D006801:Humans; D008297:Male; D014280:Triglycerides / Q000032:analysis; D014527:Uric Acid / Q000032:analysis; D014810:Vitamin E / Q000378:metabolism*
D014280:Triglycerides; D014810:Vitamin E; D014527:Uric Acid; D005340:Fibrinogen; D002784:Cholesterol; D005979:Glutathione Peroxidase; D001205:Ascorbic Acid