Effects of Apple Products on Plasma LDL Oxidation

Abstract

Apple products contain polyphenol antioxidants, but human studies of apple antioxidant effects are few. The present study showed that apple and apple product intake decreased concentrations of plasma oxidized low‐density lipoprotein (LDL). Healthy, middle aged subjects were divided into 1 of 4 groups (N=16 each) for 1 mo treatment: apples (1 per day), multiple apple products (1 apple, 1 cup apple juice, 1 serving apple sauce per day), apple extract capsules (polyphenol content of 3 apples), or placebo capsules. Plasma oxidized LDL in plasma was determined by an ELISA assay kit (Alpco Diagnostics Inc.). Plasma oxidized LDL concentrations in each of the following groups showed decreased values for post‐intervention versus pre‐intervention: the apple group, the apple product group, and the apple extract group (paired t‐test p‐values < 0.05). Placebo did not show a significant effect. A possible mechanism might have been increases in the antioxidant enzyme superoxide dismutase 1 since apple intake is reported to affect these activities. However, in the present study, no consistent effect was seen for any of the apple groups for changes in superoxide dismutase 1 in red blood cells. In summary, apple product consumption can decrease plasma contents of oxidized LDL, which could present a reasonable strategy for nutritional prevention of atherosclerosis