Bonnie Bruce, DrPH, MPH, RD, FACN, Gene A. Spiller, PhD, DSc, FACN, CNS, Leslie M. Klevay, MD, and Sandra K. Gallagher
Sphera Foundation, Los Altos, California (B.B., G.A.S.), USDA-ARS Human Nutrition Research Center, Grand Forks, North Dakota (L.M.K., S.K.G.)
Objective: Diets rich in whole and unrefined foods, like whole grains, dark green and yellow/orange-fleshed vegetables and fruits, legumes, nuts and seeds, contain high concentrations of antioxidant phenolics, fibers and numerous other phytochemicals that may be protective against chronic diseases. This study compared the effects of a phytochemical-rich diet versus a refined-food diet on lipoproteins, antioxidant defenses and colon function.
Methods:Twelve hyperlipidemic women followed two diets for four weeks starting with a refined-food diet. Subjects then directly crossed over to the phytochemical-rich diet. Duplicate, fasting serum lipids and single, fasting antioxidant enzymes were measured at the end of the four-week refined-food diet period (baseline) and again at the end of the phytochemical-rich diet period.
Results: Total energy and total fat intake were similar during both diet periods, but there was a decrease in saturated fat (SFA) of 61% in the phytochemical-rich diet group. Dietary fiber, vitamin E, vitamin C, and carotene intakes were 160%, 145%, 160% and 500% more, respectively, than during the refined-food diet period. The phytochemical-rich diet induced a drop of 13% in total cholesterol (TC) (p<0.05)and 16% (p<0.001) in low density lipoprotein-cholesterol (LDL-C). Erythrocyte superoxide dismutase decreased 69% (p<0.01) and glutathione peroxidase dropped 35% (p<0.01). Colon function was improved on the phytochemical-rich diet.
Conclusions: A diet abundant in phytochemically-rich foods beneficially affected lipoproteins, decreased need for oxidative defense mechanisms and improved colon function.