Hydrophilic antioxidant capacities of vegetables and fruits commonly consumed in Japan and estimated average daily intake of hydrophilic antioxidants from these foods

The sum of hydrophilic antioxidants of 23 vegetables and 13 fruits commonly consumed in Japan was evaluated by a modified hydrophilic-oxygen radical absorbance capacity (H-ORAC) method. The “typical vegetable” and “typical fruit” in Japan contained hydrophilic antioxidants that are equivalent to 6.95 and 12.23 μmol of Trolox per g of the edible portion, respectively, on average. Hence, the daily intake of hydrophilic antioxidants from vegetables and fruits was estimated to be 4423 μmol Trolox equivalent (TE)/d based on data of the National Health and Nutrition Survey in Japan. However, the biological significance of these antioxidant values has not yet been clarified. To address this issue, our data will provide a foundation for high-quality epidemiological studies aimed at elucidating the relationship between daily intake of antioxidants and health. In addition, the comparison of the results of the H-ORAC assay with those of polyphenol content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was also studied. The H-ORAC values had a strong positive correlation with polyphenol contents (r = 0.956), and were 1.0–18.2-times higher than the antioxidant capacities evaluated by the DPPH assay.