Saturated fat – it adds creaminess to cheese and greasiness to bacon. Lately it’s also been the key ingredient in a controversial debate. For decades, doctors and medical organizations have viewed saturated fat as the raw material for a heart attack and advised strictly limiting it. But newer research has some experts questioning whether we’ve convicted the wrong criminal.
As books and headlines embrace red meat and dairy – a June Time magazine cover even implored us to “Eat Butter” – Americans are left to wonder whether everything they thought they knew about nutrition was wrong. Should we make more room at the table for saturated fat?
What You’ve Heard
The theory that saturated fat can lead to heart disease picked up steam in the late 1950s, when a multicountry study found that heart trouble was much more common in places where people ate a lot of red meat and dairy. By 1980, the first government dietary guidelines urged Americans to cut back on saturated fat and cholesterol by limiting cream, butter, eggs, deep-fried food, and fatty cuts of red meat.
In some circles, the message hasn’t changed much. “Saturated fat is definitely bad for you,” says Penny Kris-Etherton, distinguished professor of nutrition sciences at Pennsylvania State University. “It raises LDL cholesterol, and cholesterol raises the risk of heart disease.” The latest American Heart Association guidelines recommend that people consume 5 to 6 percent of calories from saturated fat. If you eat 2,000 calories a day, that’s about 13 grams a day, or just a little more than you’d get from one Big Mac.
But Not So Fast …
More recent evidence suggests that saturated fat may not be as bad as previously thought. In the mid-1990s, a Harvard study of more than 40,000 middle-aged men found that those who ate the most saturated fat were 20 percent more likely to suffer a heart attack than those who ate the least, but researchers chalked up much of that extra risk to a lack of fiber in high-fat diets. Earlier this year, a much-publicized paper in Annals of Internal Medicine, which combined the results of 76 previous dietary studies, found no sign that people who reported eating a lot of saturated fat were more likely than anyone else to suffer from heart disease. “Current evidence does not clearly support” cutting back on saturated fat to protect the heart, the authors said.
Saturated fat can boost levels of LDL cholesterol, but those bits of cholesterol tend to be big and floppy, says Peter Attia, MD, president and director of the San Diego-based Nutrition Science Initiative, a nutrition and obesity research center. This is important because it appears that small, hard cholesterol particles – the kind not associated with saturated fat – are more likely to clog arteries. (Genetics plays a big part in the size of cholesterol particles. And ironically, some research indicates that a low-fat, high-carb diet may contribute to this kind of cholesterol pattern in people who are genetically predisposed.)
But it’s still not time to break out the bacon, says David Katz, MD, founder and director of the Yale-Griffin Prevention Research Center. The Annals study didn’t mean much, he says, because many of the study subjects who cut out saturated fat replaced those calories with sugar and carbs. In other words, the study found that eating a lot of saturated fat is as bad as eating a lot of carbs and sugar – not that saturated fat is good for you.
Fat is too complicated for easy answers, Dr. Katz says. Saturated fat comes in many different varieties, even within the same cut of meat. For example, red meat contains both stearic acid, which is likely harmless, and palmitic acid, which does seem to be dangerous – it promotes inflammation, a major driver of heart disease and many other ailments.
The Bottom Line
Experts aren’t ready to rewrite the saturated fat rules yet. Red meat and butter can be part of a healthy diet, but not if you eat them with abandon. Today’s most relevant nutrition lessons come from the Lyon Diet Heart Study, a landmark investigation from the 1990s that still sets the standard for dietary research, Dr. Katz says.
The randomized trial found that switching from a high-fat northern-European diet to a Mediterranean-style diet for nearly four years cut the risk of heart trouble by up to 70 percent. People were told to eat more vegetables with at least one serving of fruit every day. They replaced most red meat with fish or poultry and did away with butter and cream, instead using a spread similar to olive oil. “Your diet should emphasize vegetables, fruits, and whole grains,” Dr. Katz says. “If you want to add fat, do it with salmon, nuts, and seeds, with or without some lean red meat and dairy. Such a diet would either be low in fat or high in unsaturated fat. Either way, you’d be fine.”
James Dalen, MD, dean emeritus of the University of Arizona College of Medicine, doesn’t believe in strict guidelines that call for people to get a certain percentage of calories from fat or saturated fat. “We don’t need to make things so complicated,” he says. “Shop around the edges of the grocery store: the produce aisle, the meat and fish counter, the bakery for its whole grains. The center of the grocery store is where our diet has really changed over the years.”