Dietary Total Antioxidant Capacity Is Associated with Diet and Plasma Antioxidant Status in Healthy Young Adults

Dietary total antioxidant capacity (TAC), based on the cumulative antioxidant activities of all the antioxidants present in food, has been shown to be inversely associated with risks of chronic diseases. However, dietary TAC has not been validated for its relevance in a healthy young population or for reliability and predictability for antioxidant status. Our study aimed to validate TAC as a tool in assessing antioxidant intake and to investigate whether dietary TAC predicts plasma antioxidant status in a healthy young population. Sixty healthy, nonsmoking college students at the University of Connecticut ages 18 to 25 years were recruited. Thirty-day food records and two 12-hour fasting blood samples were collected for dietary and plasma antioxidant assessments. After adjustment for total energy intake, TAC from diet and supplement was positively correlated with intakes of carotenoids (P<0.01), beta carotene (P<0.05), beta-cryptoxanthin (P<0.05), flavonoids (P<0.0001), isoflavones (P<0.01), flavan-3-ols (P<0.01), flavones (P<0.05), and flavonols (P<0.0001). Dietary TAC was an independent predictor of plasma TAC determined by vitamin C equivalent antioxidant capacity (P<0.01) and by ferric-reducing ability of plasma (P<0.0001), plasma glutathione peroxidase (P<0.01), red blood cell glutathione peroxidase (P<0.05), alpha-tocopherol (P<0.05), and lutein (P<0.05). Results were similar for TAC from diet sources only. The findings suggest that dietary TAC is a good predictor of dietary and plasma antioxidant status in this sample of young adult men and women. J Acad Nutr Diet. 2012;112:1626-1635.