Differential effects of walnuts vs almonds on improving metabolic and endocrine parameters in PCOS

Abstract

Polycystic ovary syndrome (PCOS) is commonly associated with insulin resistance, dyslipidemia and increased inflammation, which all benefit from dietary intake of monounsaturated and n-3 polyunsaturated fatty acids (MUFA and n-3 PUFA). Our goal was to compare the effects of MUFA-rich almonds vs n-3/n-6 PUFA-rich walnuts on metabolic and endocrine parameters in PCOS. Thirty-one PCOS patients randomly received either walnuts or almonds containing 31 g of total fat per day for 6 weeks. At the beginning and at the end, anthropometric parameters, fasting lipids, phospholipid-fatty acids, inflammatory markers, androgens, oral glucose tolerance tests (OGTT) and frequently sampled intravenous-GTT were obtained. Weight remained stable. Within group, walnuts increased the n-3/n-6 essential PUFA in the diet and plasma phospholipids. Walnuts decreased low-density lipoprotein-cholesterol by 6% from 3.76 ± 0.27 to 3.38 ± 0.22 mmol/l (P = 0.05) and apoprotein B by 11% from 0.72 ± 0.04 to 0.64 ± 0.05 g/l (P < 0.03). Although almonds also reduced low-density lipoprotein-cholesterol by 10% and apoprotein B by 9%, these were not significant. Walnuts increased insulin response during OGTT by 26% (P < 0.02). Both walnuts and almonds increased adiponectin (walnuts from 9.5 ± 1.6 to 11.3 ± 1.8 μg per 100 ml, P = 0.0241; almonds from 10.1 ± 1.5 to 12.2 ± 1.4 μg/dl, P = 0.0262). Walnuts decreased HgBA1 from 5.7 ± 0.1 to 5.5 ± 0.1% (P = 0.0006) with significant intergroup difference from almonds (P=0.0470). Walnuts increased sex hormone-binding globulin from 38.3 ± 4.1 to 43.1 ± 4.3 nmol/l (P=0.0038) and almonds reduced free androgen index from 2.6 ± 0.4 to 1.8 ± 0.3 (P = 0.0470). Nut intake exerted beneficial effects on plasma lipids and androgens in PCOS.