We already knew that eating a diet high in fiber and low in saturated fat improves people’s overall cholesterol levels and lowers their heart risk. Now a new study shows that boosting the amount of monounsaturated fat — from sources like avocados, nuts and sunflower oil — in an already heart-healthy diet does even more to benefit the heart, raising people’s levels of good cholesterol and lowering levels of bad cholesterol.
In the study, published Nov. 8 in the Canadian Medical Association Journal, researchers in Toronto recruited 24 men and women with mild or moderately high cholesterol. The volunteers were first put on a month-long low-fat diet, then were assigned to another month of eating a vegetarian diet that was either high or low in monounsaturated fat. In the high–monounsaturated fat diet, 13% of the calories from carbohydrates were replaced with calories from sunflower or avocado oil. (More on Time.com: Special Report: Overcoming Obesity)
By the end of the month, the dieters in the high-fat group had increased their high-density lipoprotein (HDL, or good cholesterol) levels by 12.5% and reduced their low-density lipoprotein (LDL, or bad cholesterol) by 35%. The low-fat group also reduced their LDL levels by 35%, but their HDL levels did not change. Additionally, the high-fat group reduced their overall LDL-to-HDL cholesterol ratio by 6.5% — having a lower ratio is is known to be better for the heart. The high-fat group also significantly decreased their levels of C-reactive protein, a blood marker of inflammation that is associated with a higher risk of heart attack. (More on Time.com: Who Should Take Statins? The Debate Continues)
Researchers supplied the volunteers’ food throughout the two months of monitored eating, but the diet studied was markedly different from the usual diet of average Canadians. For more realistic results, researchers hope to do an observational study with a larger group to see how self-monitoring and motivation affect results.
If you’re interested in adopting a heart-healthy, high–monounsaturated fat diet, such as the Mediterranean diet, see the Mayo Clinic’s helpful tips here.
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