Information about the Aspen Ideas Festival is here. I am scheduled for a session, The American Wellness Paradox, currently scheduled from 11:00-11:50 a.m., at the East Lawn Tent. This will be a discussion with senior HHS policy advisor, Calley Means. Here’s the blurb on it: “Americans are spending more than ever on healthcare, supplements, wellness trends, and “clean eating,” yet rates of chronic disease and metabolic illness continue to climb. As skepticism fuels the rise of movements like MAHA, debates over what Americans should eat have become deeply cultural, political, and economic. Two influential voices with sharply different perspectives on nutrition and food science explore how food systems, farming practices, consumer culture, and the wellness industry collided to create one of the defining public health debates of our time.”
Saturated fat vs. heart disease: current state of the science
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:
- Convincing evidence that replacing saturated fat with polyunsaturated decreases the risk of CHD.
- Probable evidence that replacing saturated fat with largely refined carbohydrates (starch and sugar) has no benefit and even may increase the risk of CHD.
- Insufficient evidence relating to the effect on the risk of CHD of replacing saturated fat with monounsaturated fats or whole grain carbohydrates, but a trend suggesting that these might decrease CHD risk.
- Possible positive relationship between saturated fat and increased risk of diabetes.
- Insufficient evidence for establishing any relationship of saturated fat with cancer.
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.
