Almario, R.U., V. Vonghavaravat, R. Wong, S.E. Kasim-Karakas, 2001. Effects of walnut consumption on plasma fatty acids and lipoproteins in combined hyperlipidemia. Am J Clin Nutr. 74:72-9
BACKGROUND: Epidemiologic studies show an inverse relation between nut consumption and coronary heart disease. OBJECTIVE: We determined the effects of walnut intake on plasma fatty acids, lipoproteins, and lipoprotein subclasses in patients with combined hyperlipidemia. DESIGN: Participants sequentially adhered to the following diets: 1) a habitual diet (HD), 2) a habitual diet plus walnuts (HD+W), 3) a low-fat diet (LFD), and 4) a low-fat diet plus walnuts (LFD+W). RESULTS: In 13 postmenopausal women and 5 men (x ± SD age 60 ± 8 y), walnut supplementation did not increase body weight despite increased energy intake and the LFD caused weight loss (1.3 ± 0.5 kg; P < 0.01). When comparing the HD with the HD+W, linoleic acid concentrations increased from 29.94 ± 1.14% to 36.85 ±1.13% and ?-linolenic acid concentrations increased from 0.78 ± 0.04% to 1.56 ± 0.11%. During the LFD+W, plasma total cholesterol concentrations decreased by 0.58± 0.16 mmol/L when compared with the HD and by 0.46 ± 0.14 mmol/L when compared with the LFD. LDL-cholesterol concentrations decreased by 0.46 ± 0.15 mmol/L when compared with the LFD. Measurements of lipoprotein subclasses and particle size suggested that walnut supplementation lowered cholesterol preferentially in small LDL (46.1 ± 1.9% compared with 33.4 ± 4.3%, HD compared with HD+W, respectively; P < 0.01). HDL-cholesterol concentrations decreased from 1.27 ± 0.07 mmol/L during the HD to 1.14 ± 0.07 mmol/L during the HD+W and to 1.11 ± 0.08 mmol/L during the LFD. The decrease was seen primarily in the large HDL particles. Conclusions: Walnut supplementation may beneficially alter lipid distribution among various lipoprotein subclasses even when total plasma lipids do not change. This may be an additional mechanism underlying the anti-atherogenic properties of nut intake.