Blackberries decrease DNA damage after 3 h, but not after 6 d, in healthy adult volunteers

This controlled feeding intervention investigated the effect of dietary blackberries on DNA damage in humans. Healthy adults (n=51, age≥40) consumed a wash‐in diet for 3 d followed by an intervention diet on which they were randomized to receive either 300 g blackberries or an isocaloric gelatin control at breakfast for 6 d. Urinary 8‐oxo‐7′8‐dihydro‐2′‐deoxyguanosine (8‐oxodG) excretion was determined by UHPLC‐MS/MS and values were normalized to urine specific gravity. Mean 8‐oxodG values were 29% lower 3 h after blackberry consumption compared to fasting (14.6±9.6 at 0 h, 11.3±8.7 pmol/mL at 3, P =0.043), and were 24% higher 3 h after gelatin consumption (13.5±10.1 at 0 h, 16.7±13.3 at 3, P =0.013). On d 6 there were no significant differences in 8‐oxodG excretion in either group compared to baseline (11.6±7.1 pmol/mL, P =0.44 control; 14.4±9.3, P =0.67 berries), and 8‐oxodG values increased non‐significantly in both groups 3 h after treatment (15.4±11.4 pmol/mL, P =0.07 control; 18.3±16.9, P =0.29 berries). Age, sex, and BMI were not associated with treatment effects. These findings demonstrate that blackberries may be effective against short‐term DNA damage but this effect appeared to disappear after 6 d. Mechanisms for the long‐term acclimation to berry feeding are currently under investigation. Support: NIH/USDA