Could Unsaturated Fats Decrease Heart Disease Risk?

Replacing saturated fats with unsaturated fats and high-quality carbohydrates makes the most impact on lowering the risk of heart disease, according to a new study.

In an analysis of data from Nurses’ Health Study, investigators studied a cohort of 121,701 female nurses enrolled in 1976, and a cohort of 51,529 men enrolled in the Health Professionals Follow-up Study in 1986. For this study, a team including researchers from the Harvard T.H. Chan School of Public Health followed 84,628 women and 42,908 men who were free of diabetes, cardiovascular disease, and cancer, and documented 7,667 incidents of coronary heart disease.
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For the study, patients provided diet information, as well as details on their lifestyles, medical history, and newly diagnosed diseases by completing a questionnaire at baseline, and every 2-to-4 years following for the next 24 to 30 years. Participants were asked how often they consumed specific foods in the past year, and in what quantities. Patients were also asked to specify the types of fats or oil used for frying, baking, and at the table. The authors validated the questionnaire against biomarkers of dietary fatty acids.

Generally, participants replaced calories from saturated fatty acids with calories from low-quality carbohydrates, such as white bread or potatoes, as opposed to calories from the unsaturated fats contained in vegetable oils, nuts, and seeds, or high-quality carbohydrates such as those found in whole grains.

The team found that replacing 5% of energy intake from saturated fats with the equivalent intake from either polyunsaturated fats, monounsaturated fats, or carbohydrates from whole grains was linked to reducing the risk of coronary heart disease by 25%, 15%, and 9%, respectively. Meanwhile, replacing 5% of energy intake from saturated fats with carbohydrates from refined starches or sugars suggested no connection to either increased or decreased coronary heart disease risk, according to the authors, who note that changes such as cooking with healthy fats such as canola oil, olive oil, or other vegetable oils and replacing potato chips and cookies with peanuts, almonds, and olives could help lower heart disease risk.  

Given these findings, the investigators suggest that primary care physicians “help their patients who are at high risk of heart disease to limit their consumption of saturated fat or refined carbohydrates, instead increasing their intake of unsaturated fats or healthy carbohydrates, such as whole grains,” says Yanping Li, PhD, research scientist in the department of nutrition at the Harvard T.H. Chan School of Public Health, and study co-author.

—Mark McGraw

Reference

Li Y, Hruby A, Bernstein AM, et al. Saturated fats compared with unsaturated fats and sources of carbohydrates in relation to risk of coronary heart disease. J Am Coll Cardiol. 2015;66(14):1538-1548