Mary Hartley, RD, MPH, is the director of nutrition for Calorie Count, providing domain expertise on issues related to nutrition, weight loss and health. She creates original content for weekly blogs and newsletters, for the Calorie Count library, and for her popular daily Question-and-Answer section, Ask Mary. Ms. Hartley also furnishes direction for the site features and for product development.
Saturated fat was recently in the news at the Institute of Food Technologists expo when experts revealed, again, that the link between saturated fat and cardiovascular disease is inconclusive. Both the public and professionals are now confused, since diets low in fat, particularly saturated fat, have been the mainstay of scientific consensus for more than 30 years. Saturated fat, a solid fat mainly found in animal foods, includes cheese, whole milk, butter, and fatty cuts of meat. It, together with liquid poly- and mono-unsaturated fats from nuts, seeds, grains and fish, make up all naturally-occurring dietary fat.
Back in the 1970s, the American Heart Association and other authorities said to reduce all fat to 30 percent of total calories and saturated fat to 10 percent or less. The recommendation was drawn from epidemiologic studies that compared the diets among different countries, in particular, the Seven Countries Study. Those studies showed a correlation between total fat intake and rates of heart disease. That, along with the National Diet-Heart Study of the 1960s, form the basis of the message that reduction in saturated fat lowers blood cholesterol and risk of heart disease.
But hypotheses are made to be disproven, and recent, better studies have challenged the status quo. Several randomized clinical trials showed that fat intake, as a percent of total calories, was not associated with heart disease. Well-designed meta-analyses published in first-class medical journals went support those findings. Large prospective cohort studies, like the Women’s Health Initiative and the Nurses Study, did not find a link between saturated fat consumption and cardiovascular disease. Other research showed that, compared to low fat diets, diets high in polyunsaturated fats did more to reduce the risk. When the food industry developed “fat-free” products that replaced fat with refined carbohydrates, we were lead to see that excess sugar created its own risk for heart disease.
The take-away message is that modern evidence does not support a major role for saturated fat on cardiac risk. Still, it is unwise to eat a lot of saturated fat because it displaces the polyunsaturated fat and other nutrients you need. To be sure, the Dietary Guidelines for Americans, 2024 say, “Consume less than 10 percent of calories from saturated fatty acids by replacing them with monounsaturated and polyunsaturated fatty acids” and “limit the consumption of foods that contain refined grains, solid fats and added sugars.”
The newer studies have shown that calorie balance and diet quality are more important than restricting fat. For heart health and overall health, the diet must include fruit, vegetables, whole grains, beans, fish, lean meat, low-fat dairy, and vegetables oils. A low-fat diet that is full of refined carbohydrates should not be seen as healthy.
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