Effect of dietary patterns on measures of lipid peroxidation: results from a randomized clinical trial.

BACKGROUND Free radical-mediated oxidative damage to lipids is thought to be an important process in the pathogenesis of atherosclerosis. Although previous studies have demonstrated a beneficial impact of antioxidant vitamin supplements on lipid peroxidation, the effect of dietary patterns on lipid peroxidation is unknown. METHODS AND RESULTS During the 3-week run-in period of a randomized trial, 123 healthy individuals were fed a control diet, low in fruits, vegetables, and dairy products, with 37% of calories from fat. Participants were then randomized to consume for 8 weeks: (1) the control diet, (2) a diet rich in fruits and vegetables but otherwise similar to the control diet, and (3) a combination diet rich in fruits, vegetables, and low-fat dairy products and reduced in fat. Serum oxygen radical-absorbing capacity, malondialdehyde (an in vitro measure of lipid peroxidation), and breath ethane (an in vivo measure of lipid peroxidation) were measured at the end of run-in and intervention periods. Between run-in and intervention, mean (95% CI) change in oxygen radical-absorbing capacity (U/mL) was -35 (-93, 13) in the control diet, 26 (-15, 67) in the fruits and vegetables diet (P=0.06 compared with control), and 19 (-22, 54) in the combination diet (P=0.10 compared with control). Median (interquartile range) change in ethane was 0.84 (0.10, 1.59) in the control diet, 0.02 (-0.61, 0.83) in the fruits and vegetables diet (P=0.04 compared with control), and -1.00 (-1.97, 0.25) in the combination diet (P=0.005 compared with control). Change in malondialdehyde did not differ between diets. CONCLUSIONS This study demonstrates that modification of diet can favorably affect serum antioxidant capacity and protect against lipid peroxidation.