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3 Clinical Nutrition and Risk Factor Modification Center, and 4 Department of Medicine, Division of Endocrinology and Metabolism; St. Michael's Hospital, Toronto, Ontario M5C 2T2; 5 Department of Nutritional Sciences; Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3E2; 6 Almond Board of California, Modesto, CA 95354; and 7 Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111
* To whom correspondence should be addressed. E-mail: cyril.kendall{at}utoronto.ca.
Nut consumption has been associated with reduced coronary heart disease (CHD) risk. In addition to cholesterol-lowering properties, almonds have been shown to lower oxidized LDL concentrations. However, little is known regarding their effects on other markers of oxidative stress. The dose-response effects of whole almonds, taken as snacks, were compared with low-saturated fat (<5% energy) whole-wheat muffins (control) in the therapeutic diets of hyperlipidemic subjects. In a randomized crossover study, 27 hyperlipidemic men and women consumed 3 isoenergetic (mean 423 kcal/d or 1770 kJ/d) supplements each for 1 mo. Supplements consisted of full-dose almonds (73 ± 3 g/d), half-dose almonds plus half-dose muffins (half-dose almonds), and full-dose muffins (control). Subjects were assessed at wk 0, 2 and 4. Mean body weights differed
300 g between treatments, although the weight loss on the half-dose almond treatment was greater than on the control (P < 0.01). At 4 wk, the full-dose almonds reduced serum concentrations of malondialdehyde (MDA) (P = 0.040) and creatinine-adjusted urinary isoprostane output (P = 0.026) compared with the control. Serum concentrations of
- or
-tocopherol, adjusted or unadjusted for total cholesterol, were not affected by the treatments. Almond antioxidant activity was demonstrated by their effect on 2 biomarkers of lipid peroxidation, serum MDA and urinary isoprostanes, and supports the previous finding that almonds reduced oxidation of LDL-C. Antioxidant activity provides an additional possible mechanism, in addition to lowering cholesterol, that may account for the reduction in CHD risk with nut consumption.