Journal of the American College of Nutrition, Vol. 22, No. 3, 217-223 (2003) Published by the American College of Nutrition. Original Research. Authors: Hwa-Young Kim, MSc, Ok-Hee Kim, PhD and Mi-Kyung Sung, PhD Department of Food and Nutrition, Sookmyung Women’s University (H.-Y.K., M.-K.S.), Seoul, KOREA National Institute of Toxicological Research, Korea Food and Drug Administration (O.-H.K.), Seoul, KOREA
Address reprint requests to: Mi-Kyung Sung, Ph.D., Associate Professor, Department of Food and Nutrition, Sookmyung Women’s University, 53-12 Chungpa-dong 2-ka, Yongsan-ku Seoul, 140-742, KOREA. Email: firstname.lastname@example.org
Objective: Epidemiological studies have suggested beneficial effects of dietary polyphenols in reducing the risk of chronic diseases. This study was performed to investigate the effects of polyphenol-depleted and polyphenol-rich diets on blood oxidative stress markers and urinary excretions of major phenols.
Methods: Nineteen healthy female non-smokers 19 to 21 years of age took part in the study, which consisted of two dietary intervention periods separated by three days. Experimental diets were composed of common foods selected to comply with low contents of polyphenols for phenol-depleted intervention and high contents of polyphenols for phenol-rich diets. Blood and urine samples were collected on day 0, 3 and 6 of each intervention. Duplicate portions of foods provided to the subjects were also collected.
Blood oxidative stress markers included plasma antioxidant vitamins, erythrocyte superoxide dismutase (SOD) activity and lymphocyte DNA damage. Urinary excretions of major phenols were measured to affirm bioavailability of dietary phenols.
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Results: Plasma -tocopherol and ß-carotene concentrations were slightly decreased on day 3 and 6 of the phenol-depleted dietary intervention period, although no change was observed with phenol-rich diets. The erythrocyte SOD activity was also slightly decreased during phenol-depleted dietary intervention.
However, at day 6 of the phenol-rich intervention, the activity of SOD was significantly increased by 41%. Tail moment and tail length of lymphocyte DNA as markers of DNA damage were higher on day 6 of phenol-depleted intervention, although only tail moment showed a statistical significance.
The average intakes of quercetin and kaempferol during the phenol-rich intervention were 21 mg/day and 9 mg/day, respectively. The average urinary excretion rates during phenol-rich intervention were 2.06% for quercetin and 0.46% for kaempferol. There were positive correlations between erythrocyte SOD activity and urinary concentration of quercetin or kaempferol.
Conclusions: These results suggest that polyphenol-rich diets may decrease the risk of chronic diseases by reducing oxidative stress.
Key words: polyphenols, antioxidants, DNA damage, quercetin, kaempferol