A new study calls into question established wisdom on good and bad fats, but the American Heart Association stands by its guidelines that saturated fats can hurt your heart while polyunsaturated fats may help it.
The study, published in today’s Annals of Internal Medicine, concludes that there isn’t enough evidence to prove the benefits of getting more polyunsaturated fat and less saturated fat in the diet. It’s a meta-analysis, meaning it combines data from previous studies.
The American Heart Association is concerned that the study’s conclusion could be deceptive for some people as they decide what to put on their plates.
“You might think, ‘I guess I don’t need to worry about saturated fat,’ and that’s not true,” said Linda Van Horn, a registered dietitian and professor of preventive medicine at Northwestern University’s Feinberg School of Medicine.
Saturated fats are found in animal products, many baked and fried goods, meats, butter and cheese. They raise blood cholesterol and increase the risk of heart disease and stroke, the two leading causes of death in the world. Polyunsaturated fats, which include some liquid vegetable oils and fatty fish like salmon, sardines, mackerel, herring and trout, may help reduce blood cholesterol and lower the risk of heart disease.
The study published Monday doesn’t change the American Heart Association recommendation of a diet that’s rich in fruits and vegetables, whole grains, nuts, fish and unsaturated fats. Saturated and trans fats should make up less than 6 percent of the diet, according to the association’s cardiovascular prevention guidelines.
“This research simply means that we lack the data from controlled clinical trials that truly test this question of how much saturated fat is acceptable, so we must rely on existing science that suggests that saturated fat is atherogenic, meaning it tends to promote the formation of fatty plaques in the arteries,” said Van Horn, who is also a volunteer for the American Heart Association.
New studies will require billions of dollars and decades to complete.
Van Horn said the study provides new insight into individual fatty acids and how they affect our health. “The American Heart Association values the opportunity to look at new data and take it into consideration regarding recommendations for a heart-healthy eating plan,” she said.
Trans fats, which increase LDL or “bad” cholesterol, have proven health risks, similar or worse than saturated fats. The Food and Drug Administration ruled in November that partially hydrogenated fats don’t meet the criteria for their “generally recognized as safe” category, starting the process to dramatically reduce trans fats from the food supply.
“There are absolutely no benefits associated with trans fats, and we know they are a risk to your heart health,” Van Horn said. “People who are at risk for developing Type 2 diabetes should especially avoid saturated fats.”
Everything you want to know about fats on our Fats 101 page