Accumulating research over the past few years has contradicted the long prevailing belief that lowering cholesterol by reducing saturated fat in the diet protects against heart disease. In fact, it appears the opposite is true – while you can lower blood cholesterol levels with diets that are very low in saturated fat, studies have shown that this doesn’t reduce the risk of death from heart disease.
Evidence of this first showed up in long-neglected findings from a study conducted from 1968 to 1973. It looked at the effect of diet on the heart health of 9,423 men and women in Minnesota state mental hospitals and a nursing home. Half the participants were assigned a typical American diet that included beef, milk and cheese, all high in saturated fat, while the rest were put on a diet that replaced saturated fat with polyunsaturated corn oil and corn oil margarine. The researchers theorized that the diet with the polyunsaturates would be heart protective.
That didn’t happen, but we didn’t know it until recently. The results were never fully analyzed at the time. When they finally were published in April 2016, they showed that although cholesterol levels in participants who consumed the least saturated fat dropped by an average of 14 percent, this didn’t lead to a lower mortality risk. Instead, the mortality rate was actually higher among these seniors than it was in the group that didn’t cut back on saturated fat.
More along these lines came from a scientific analysis of 21 earlier studies, which found “no significant evidence” that dietary saturated fat is associated with an increased risk of coronary heart disease. The studies analyzed included data on nearly 348,000 participants, most of whom were healthy when they were enrolled in the various investigations. Researchers followed them for five to 23 years, during which 11,000 developed heart disease or had a stroke. No difference was found in the risk of coronary heart disease, stroke, or coronary vascular disease between those with the lowest and the highest intakes of saturated fat. Apparently, many studies used to support the low-fat recommendations of the past were seriously flawed.
The latest study on the subject followed 135,335 people age 35 to 70 in 18 countries for more than seven years. Published in 2017, this research found that people who ate the most fat (an average of 35.3 percent of calories) were 23 percent less likely to die than those whose fat intake was lowest (an average of 10.6 percent of total calories). And it didn’t matter whether the fat was saturated, polyunsaturated or monounsaturated. The higher fat diets also were associated with a lower risk of stroke. The same study found that people who ate the most carbohydrates (77 percent of total calories, including carbs from fruits and vegetables) had a higher risk of dying (not necessarily of cardiovascular disease) than those who ate the lowest amount of carbs (46 percent of total calories).
Given these findings and the fact that foods high in saturated fat (bacon, conventionally raised beef, processed cheese) are not the best options for overall health, I recommend budgeting consumption of it to about 10 percent of daily calories. You can “spend” those calories on ice cream, butter, high-quality natural cheese, or even an occasional steak (from organic, grass-fed, grass-finished cattle, please). Minimize intake of poultry fat (concentrated just beneath the skin) because it contains inflammation-promoting arachidonic acid.
Andrew Weil, M.D.
Andrew Mente et al, “Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study.” The Lancet, November 4, 2017, DOI: doi.org/10.1016/S0140-6736(17)32252-3
Christopher E. Ramsden et al, “Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73).” BMJ, April 12, 2016, doi: dx.doi.org/10.1136
Patty W. siri-Tarino et al, “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.” American Journal of Clinical Nutrition, January 13, 2010, doi: 10.3945/ajcn.2009.27725