Serum Antioxidant Capacity Is Increased by Consumption of Strawberries, Spinach, Red Wine or Vitamin C in Elderly Women

Guohua Cao, , Robert M. Russell, Neal Lischner and Ronald L. Prior

USDA-ARS, Jan Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111 and Nutritional Science Department, University of Connecticut, Storrs, CT 06269.

ABSTRACT
It is often assumed that antioxidant nutrients contribute to the protection afforded by fruits, vegetables, and red wine against diseases of aging. However, the effect of fruit, vegetable and red wine consumption on the overall antioxidant status in humans is unclear. In this study we investigated the responses in serum total antioxidant capacity following consumption of strawberries (240 g), spinach (294 g), red wine (300 ml) or vitamin C (1250 mg) in eight elderly women. Total antioxidant capacity was determined using different methods: oxygen radical absorbance capacity (ORAC) assay, Trolox equivalent antioxidant capacity (TEAC) assay and ferric reducing ability (FRAP) assay. The results showed that the total antioxidant capacity of serum determined as ORAC, TEAC, and FRAP, using the area under the curve, increased significantly by 7-25% during the 4-h period following consumption of red wine, strawberries, vitamin C and spinach. The total antioxidant capacity of urine determined as ORAC increased.

(P< 0.05) by 9.6, 27.5, and 44.9% for strawberries, spinach, and vitamin C, respectively, during the 24-h period following these treatments. The plasma vitamin C level after the strawberry drink, and the serum urate level after the strawberry and spinach treatments, also increased significantly. However, increased vitamin C and urate levels could not fully account for the increased total antioxidant capacity in serum following the consumption of strawberries, spinach, or red wine, which are rich in antioxidant phenolic compounds, can increase the serum antioxidant capacity in humans.

J. Nutr. 128: 2383-2390, 1998