Serum lipid effects of a high-monounsaturated fat diet based on macadamia nuts

Background: Recent studies have identified potential beneficial effects of eating nuts, most of which have substantial amounts of monounsaturated fats . Macadamia nuts are 75% fat by weight, 80% of which is monounsaturated. Objective: To examine variations in serum lipid levels in response to a hig h-monounsaturated fat diet based on macadamia nuts. Methods: A randomized crossover trial of three 30-day diets was conducted i n 30 volunteers aged 18 to 53 years from a free-living population. Each was fed a "typical American" diet high in saturated fat (37% energy from far); an American Heart Association Step 1 diet (30% energy from fat); and a mac adamia nut-based monounsaturated fat diet (37% energy From fat) in random o rder. Serum total cholesterol, high-density lipoprotein cholesterol, and tr iglyceride levels were measured. Results: Mean total cholesterol level after the typical American diet was 5 .20 mmol/L (201 mg/dL). After the Step 1 diet and the macadamia nut diet, t otal cholesterol level was 4.99 mmol/L (193 mg/dL) and 4.95 mmol/L (191 mg/ dL). respectively. Low-density lipoprotein cholesterol level was 3.37 mmol/ L (130 mg/dL) (typical diet), 3.21 mmol/L(124 mg/dL) (Step 1 diet), and 3.2 2 mmol/L (125 mg/dL) (macadamia nut diet). High-density lipoprotein cholest erol level was 1.43 mmol/L (55 mg/dL) (typical), 1.34 mmol/L (52 mg/dL) (St ep 1), and 1.37 mmol/L (53 mg/dL) (macadamia nut). Lipid values after the S tep 1 and macadamia nut diets were significantly different from those after the typical diet (P<.05). Conclusions: The macadamia nut-based diet high in monounsaturated fat and t he moderately low-fat diet both had potentially beneficial effects on chole sterol and low-density lipoprotein cholesterol levels wizen compared with a typical American diet.