HAMILTON, ONT. — Saturated fats were not associated with all-cause mortality, cardiovascular disease, coronary heart disease, ischemic stroke or type 2 diabetes in a systematic review funded by the World Health Organization. Any health effects associated with replacing saturated fats in products may depend on what ingredients replace them, according to the review, which appeared on-line Aug. 12 in the BMJ.
Trans fats, on the other hand, were associated with all-cause mortality, coronary heart disease and coronary heart disease mortality in the review
“Dietary guidelines must carefully consider the health effects of recommendations for alternative macronutrients to replace trans fat and saturated fats,” the authors of the review said.
Few observational studies have modeled the effect of replacing saturated fat or trans fat with other nutrients, they said.
“In large prospective studies, when polyunsaturated fats replace saturated fats, risk of CHD (coronary heart disease) is reduced but not when MUFA (monounsaturated fatty acids) or carbohydrate is the replacement choice,” they said.
Dietary advice tends to recommend limiting intake of both saturated fat and trans fat. The American Heart Association recommends that healthy Americans over age 2 limit their saturated fat intake to less than 7% of total daily calories and their trans fat intake to less than 1%. The 2015 Dietary Guidelines Advisory Committee recommended people limit daily saturated fat intake to less than 10% of total calories. The W.H.O. said lowering saturated fat intake to less than 10% of total energy intake and trans fats to less than 1% reduces the risk of developing non-communicable diseases.
The study appearing in the BMJ involved researchers from McMaster University and Hamilton Health Sciences in Hamilton, Ont., as well as from the University of Toronto and the Hospital for Sick Children in Toronto. They examined 41 primary reports of associations between saturated fats and health outcomes in prospective cohort studies published between 1981 and 2014.
Risks were associated with what ingredients replaced saturated fat. A pooled analysis of 11 prospective cohort studies found replacement of saturated fat with polyunsaturated fat reduced coronary risk by 13%.
Researchers said foods high in saturated fat, particularly processed and red meat, have been associated with increased mortality and risk of cancer, but dairy foods were not consistently associated with cancers.
“The association between certain foods and CHD cannot be predicted solely by their content of total saturated fats because individual saturated fats might have different cardiovascular effects, and major food sources of saturated fats contain other constituents that could influence risk of CHD,” the researchers said.