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Despite recent publications finding no correlation between intake of saturated fat and coronary heart disease (CHD) – see, for example, the recent meta-analysis in the American Journal of Clinical Nutrition – the debates over the role of saturated fat continue.
In that same issue of the Journal, another study says that reducing saturated fat only works if you replace it with something better. If you replace saturated fat with carbohydrates, the effects on heart disease will be worse.
The fat story is not simple (in What to Eat, I explain the biochemistry of food fats in the chapter on fats and oils and in an appendix). The main reason for the complexity is that different kinds of fats do not occur separately in foods.
Without exception, food fats are mixtures of three kinds of fatty acids: saturated (no double bonds and solid at room temperature), monounsaturated (one double bond), and polyunsaturated (two or more double bonds and liquid at room temperature). Food fats just differ in proportions of the three kinds.
Meat, dairy, and egg fats generally are more saturated. Plant fats and oils are generally more unsaturated.
How to make sense of the saturated fat story? An expert panel from WHO and FAO just produced a new review of the evidence. The panel evaluated CHD morbidity and mortality data from epidemiological studies and controlled clinical trials. It found:
The panel’s recommendations: (1) Replace saturated fat with polyunsaturated fats (omega-3 and omega-6) in the diet, and (2) Limit saturated fat to 10% of daily calories or less.
Translation: Eat less animal fat and replace it with vegetable fats.
Historical note: These are precisely the same recommendations that have been standard in the U.S. for at least fifty years. This was good advice in the late 1950s. It is still good advice.
UPDATE, March 22,2011: Another major review has just come to precisely the same conclusions, this one from an international expert panel. It also suggests areas for future research. See American Journal of Clinical Nutrition 2011;93:684-88.