New Findings Contradict Nutritional Guidelines on Reduced Fat Intake

Replacing saturated fatty acids with carbohydrates has a negative effect on blood lipids, according to a recent study. The results contradict current guidelines that recommend reducing total fat and saturated fatty acid intake to improve cardiovascular disease (CVD) risk.

Little is known about the association between dietary nutrients and risk markers for CVD across different regions worldwide.
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For the Prospective Urban Rural Epidemiology (PURE) study, the researchers evaluated 125,287 participants from 18 countries, including the United States, from January 1, 2003, to March 31, 2013.

Food frequency questionnaires were administered to participants, and multilevel modeling was used to determine the associations between nutrient intake and risk markers for CVD.

Using a simulation model, the researchers assumed that the effects of saturated fatty acids on CVD events were solely related to their association through an individual risk marker, and subsequently compared the simulated risk-marker–based estimates with directly observed associations between saturated fatty acids and CVD events.

Results indicated that the intake of total fat and each type of fat was associated with higher levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and ApoA1, and was associated with lower levels of triglycerides, ratio of total cholesterol to HDL cholesterol, ratio of triglycerides to HDL cholesterol, and ratio of ApoB to ApoA1.

Furthermore, a high carbohydrate intake was associated with lower total cholesterol, LDL cholesterol, ApoB, HDL cholesterol, and ApoA1, as well as higher triglycerides, ratio of total cholesterol to HDL cholesterol, ratio of triglycerides to HDL cholesterol, and ratio of ApoB to ApoA1. Higher intakes of total fat, saturated fatty acids, and carbohydrates were associated with higher blood pressure, while a high intake of protein was associated with lower blood pressure.

Ultimately, the researchers found that replacing saturated fatty acids with carbohydrates was associated with the most adverse effects on lipids.

“Our data are at odds with current recommendations to reduce total fat and saturated fats,” the researchers concluded. “Reducing saturated fatty acid intake and replacing it with carbohydrate has an adverse effect on blood lipids. Substituting saturated fatty acids with unsaturated fats might improve some risk markers, but might worsen others. Simulations suggest that ApoB-to-ApoA1 ratio probably provides the best overall indication of the effect of saturated fatty acids on cardiovascular disease risk among the markers tested. Focusing on a single lipid marker such as LDL cholesterol alone does not capture the net clinical effects of nutrients on cardiovascular risk.”

—Christina Vogt

Reference:

Mente A, Dehghan M, Rangarajan S, et al; Prospective Urban Rural Epidemiology (PURE) study investigators. Association of dietary nutrients with blood lipids and blood pressure in 18 countries: a cross-sectional analysis from the PURE study. Lancet Diabetes Endocrinol. 2017;5(10):774-787. http://dx.doi.org/10.1016/S2213-8587(17)30283-8.