Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2002
Publication Date: 11/14/2002
Interpretive Summary: People that eat a large amount of fruits and vegetables have less chronic disease, like heart disease and cancer, than people who eat few fruits and vegetables. Some evidence suggests that the link between high fruit/vegetable intake and reduced chronic disease may be partly explained by antioxidants in fruits and vegetables such as vitamins C and E. Antioxidants protect substances in our body from damage due to oxygen, damage similar to fats going rancid or the browning of fresh-cut apples. To determine the effect of moderate antioxidant intake on oxidant damage to the body, we measured oxidant damage to body fat and protein in 77 healthy men whose typical diet contained few fruits and vegetables (2.7 servings/d). The men, age 20-50 y, were given a daily antioxidant supplement which contained vitamin C and E in the amounts one would receive if eating about eight servings of fruits and vegetables per day. Half of the subjects were given the antioxidant supplement for 90 days, and the other half were given a look-alike placebo sugar-pill as a control. Blood and urine was taken at the beginning and end of the study to see if the supplement treatment reduced the amount of oxidant damage to body fats and proteins. The supplementation increased blood vitamin C and E levels, but had no effect on the oxidant damage measures. Therefore, moderate antioxidant supplementation of healthy young men, even those with low fruit and vegetable intakes, did not significantly reduce body oxidant damage. In healthy young men, the body's internal antioxidant defense system and a modest amount of dietary antioxidants is apparently adequate to prevent levels of body oxidant damage that can be measured by current methods.
Technical Abstract: The link between high fruit/vegetable intake and reduced chronic disease may be partly explained by antioxidant protection. To determine the effect of moderate antioxidant intake on biomarkers of oxidant damage, we assessed in vivo lipid and protein oxidation in 77 healthy men whose typical diet contained few fruits and vegetables (2.7 servings/d). The 39 non-smokers (NS) and 38 smokers (S), age 20-50 y, were given a daily supplement (272 mg vitamin C, 31 mg all-rac-alpha-tocopherol, and 400 ug folic acid), or placebo, for 90 d with their usual diet. Fasting blood and urine was taken at baseline and the end of the study (T90) for determination of plasma and urine TBARS, plasma protein carbonyls, and urine F2 -total and 8-isoprostanes. Urine TBARS was the only marker which showed a significant difference (P<0.05) at baseline between NS (mean +/- sd = 1.91 +/- 0.39) and S (2.19 +/- 0.74 umol/g creatinine). Supplementation increased plasma ascorbate and tocopherol, but had no effect on the oxidant biomarkers, mean +/- sd at baseline and T90 being: 0.44 +/- 0.14 and 0.37 +/- 0.14 mol/L for plasma TBA-MDA; 0.47 +/-0.22 and 0.47 +/- 0.26 nmol protein carbonyls/mg protein; and 16.7 +/- 11.2 and 19.1 +/- 19.3 ng F2 -isoprostanes/mg creatinine. Moderate antioxidant supplementation of healthy young men, even smokers and those with low fruit and vegetable intakes, did not significantly reduce in vivo oxidant damage. In healthy young men, the endogenous antioxidant defense system and a modest amount of dietary antioxidants is apparently adequate to prevent levels of in vivo oxidant damage that can be differentiated by current methods.