A Diet Rich in Monounsaturated Fat Raises HDL Levels

Addition of monounsaturated fat to a dietary scheme for cholesterol reduction improved the lipid profile of patients by increasing their levels of HDL (high-density lipoprotein) while lowering levels of LDL (low-density lipoprotein) and C-reactive protein.

Investigators at St. Michael's Hospital (Toronto, Canada) tested whether increasing the monounsaturated fat content of a diet proven effective for lowering LDL cholesterol (dietary portfolio) also modified other risk factors for cardiovascular disease, specifically by increasing HDL cholesterol, lowering serum triglyceride and further reducing the ratio of total to HDL cholesterol.

They worked with a group of 24 patients with hyperlipidemia who consumed a therapeutic diet very low in saturated fat for one month and were then randomly assigned to a dietary portfolio low or high in monounsaturated fatty acid for another month.

Results published in the November 1, 2010, online edition of the Canadian Medical Association Journal revealed that for patients who consumed the dietary portfolio high in monounsaturated fat, HDL cholesterol rose, whereas for those consuming the dietary portfolio low in monounsaturated fat, HDL cholesterol did not change. The ratio of total to HDL cholesterol was reduced by 6.5% with the diet high in monounsaturated fat relative to the diet low in monounsaturated fat. Patients consuming the diet high in monounsaturated fat also had significantly higher concentrations of apolipoprotein AI (a component of HDL), and their C-reactive protein was significantly lower. No treatment differences were seen for triglycerides, other lipids, or body weight, and mean weight loss was similar for the diets high in monounsaturated fat and low in monounsaturated fat.

"The replacement of 13% of total calories from carbohydrate by monounsaturated fats in the dietary portfolio resulted in a 12.5% greater increase in HDL cholesterol over the four weeks, while not altering the substantial LDL cholesterol reduction,” said first author Dr. David Jenkins, of the clinical nutrition and risk factor modification center at St. Michael's Hospital.

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