Replacing saturated fat with healthier fat in the diet lowers cardiovascular disease risk as much as cholesterol-lowering statin drugs, according to an American Heart Association advisory issued Thursday.
“This important paper reaffirms the scientific evidence that saturated fat raises LDL cholesterol, a leading cause of atherosclerosis,” said Rachel Johnson, Ph.D., R.D., a professor of nutrition at the University of Vermont, who was not an advisory author. “Furthermore, replacing saturated fat with polyunsaturated fat reduces the incidence of cardiovascular disease.”
Researchers culled hundreds of research papers published since the 1950s, finding evidence supporting the AHA’s recommendation that saturated fat should make up less than 10 percent of daily calories for healthy Americans.
Atherosclerosis is the hardening and clogging of arteries that can lead to heart attacks, strokes and other cardiovascular diseases.
Cardiovascular disease was lowered by about 30 percent, similar to the effect of cholesterol-lowering statin drugs when vegetable oil replaced saturated fat in the diet, according to the advisory. The switch to healthier oils also was associated with lower rates of death from all causes.
The finding doesn’t mean that people prescribed statins to lower heart disease risk should give up medication. Nor should they eat too much saturated fat, said Frank Sacks, M.D., lead author of the advisory and professor of cardiovascular disease prevention in the department of nutrition at the Harvard School of Public Health.
“That statin is only going to go part of the way,” he said. “You’re going to mess up the effect of the statin if you’re eating all unhealthy foods.”
The tipping point that led to the advisory was a well-publicized 2014 study that concluded that the amount of dietary and saturated fat had no bearing on the risk of heart disease, said Sacks. But the study had at least one major flaw: It didn’t consider what people ate in place of saturated fat, Sacks said.
“The people who were eating low saturated fats were eating a lot of junk food carbohydrates,” Sacks said. Trading bad fat for bad carbs doesn’t reduce cardiovascular disease, he said. “You wouldn’t tell people, ‘Hey reduce your sat fat and replace it with sugary soft drinks or donuts.’” You’d tell them to replace it with unsaturated oils, whole wheat bread, vegetables, nuts or beans, Sacks said.
The publicity surrounding the study and others has shaped public perception about saturated fats, partly reflecting the way nutrition studies are reported by news media, said Sacks.
“One of the real problems in transmitting health information is that generally people who are writing about it don’t look into what’s come before,” he said. The media also don’t pay much attention to new studies that support or extend current dietary recommendations. “The overall effect has misled the public on the science of dietary fats,” he said.
People are also quick to believe trends that aren’t supported by science, he said. A prime example is coconut oil, widely touted for its health benefits. “I just don’t know” who is pushing it, but it’s not scientists, Sacks said. It may be driven by manufacturers looking to profit, or some countries’ economic dependence on coconut oil, he said.
According to the advisory, coconut oil is 82 percent saturated fat, and studies show it raises LDL “bad” cholesterol as much as butter, beef fat or palm oil. Canola oil, on the other hand, has only 7 percent saturated fat. All fats and oils have varying levels of saturated, monounsaturated and polyunsaturated fat. One reason people may have a hard time reducing their saturated fat intake is the familiarity of foods made with it, Sacks said. “People also have a strong emotional connection to what they eat,” Sacks said. “What you’re brought up eating, what people call their comfort food -- there’s a lot of emotion in that.” But nutrition science may not support the health of that kind of eating, he said.
Overall fat intake was higher when early studies of saturated fats were done in the 1950s and 1960s, according to the advisory. The studies showed that reducing saturated fats lowered cholesterol, reduced the risk of heart attack and stroke, and in some cases lowered the risk of death from coronary heart disease.
Although people are eating less saturated fats today than in the 1950s, they still eat too much, Sacks said. Most restaurants today cook with unsaturated fats, but foods like beef and bacon still contain saturated fat.
“If you have a cheeseburger or bacon burger, you get sat[urated] fat from almost everything except the bread,” Sacks said. Despite its lower fat status, a white bread bun isn’t particularly healthy either, Sacks said.
He advises people to reduce saturated fats by not cooking with butter, but with canola, or corn oil or soybean oil, or extra virgin olive oil.
Johnson said the main sources of saturated fats are butter, lard, beef tallow, palm oil, palm kernel oil and coconut oil. Healthier oils include canola oil, corn oil, soybean oil, peanut oil, safflower oil, sunflower oil, and walnuts, she said. Olive oil, avocados and tree nuts such as almonds, cashews, hazelnuts, pistachios, and pecans are low in saturated fats, and largely composed of monounsaturated fats, Johnson said.
Surprisingly, Sacks isn’t against frying foods, even deep frying. “There’s nothing wrong with deep frying as long as you deep fry in a nice unsaturated vegetable oil,” he said.