Health

Don't Fear The Fat: Experts Question Saturated Fat Guidelines

NPR | March 18, 2014 5:50 a.m.

Contributed By:

Allison Aubrey

As a culture, we tend to suffer from the angel-or-devil mindset. Especially when it comes to food.

And for forty years now, saturated fat — found in high amounts in meat, cheese and other full-fat dairy products — has been one of our top nutritional demons.

The U.S. Dietary Guidelines urge us to limit consumption due to concerns that saturated fat raises the risk of heart disease. But after decades of research, a growing number of experts is questioning this link.

In fact, the authors of a new meta-analysis published in the Annals of Internal Medicine conclude that there’s insufficient evidence to support the long-standing recommendation to consume saturated fat in very low amounts.

So, let’s walk through this shift in thinking: The concern over fat gathered steam in the 1960s when studies showed that saturated fat increases LDL cholesterol — the bad cholesterol — the artery clogging stuff. The assumption was that this increased the risk of heart disease.

But after all this time, it just hasn’t panned out, at least not convincingly. When researchers have tracked people’s saturated fat intake over time and then followed-up to see if higher intake increases the risk of hearts attacks and strokes, they haven’t found a clear, consistent link.

In fact, the new study, finds, “null associations” (to quote the authors) between total saturated fat intake and coronary risk. And a prior analysis that included more than 300,000 participants came to a similar conclusion.

So, what explains this? Well, researchers say the relationship between cholesterol and heart disease is a lot more complicated than was once understood. LDL is just one indicator of risk.

What’s now thought to be a more important predictor of risk is the ratio a person has of LDL to HDL, the good cholesterol. And there’s evidence that, compared to carbohydrates, saturated fat can increase HDL and lower fat deposits in the blood called triglycerides, which, in theory, would be protective against heart disease.

“So when you put this all together,” says Dariucsh Mozaffarian, MD of Harvard and a co-author of the paper, what you see is that saturated fat has a relatively neutral effect. It’s “not a beneficial effect, but not a harmful effect. And I think that’s what the recent studies show.”

So, where does this lead us? Lots of experts say the lesson here is that you can’t take a reductionist approach to good health.

Look what happened when Americans reduced fat intake at the height of the fat-free boom in the early 1990s, and compensated by eating lots of carbohydrates. All of the calories from refined grains (think fat free bagels and low-fat cookies) led lots of folks to gain weight.

“There were definitely unintended, harmful consequences of the low-fat craze,” Mozaffarian says.

He says the lesson is to get away from recommendations that are built on single nutrients. A healthy diet, he says, should include a wide variety of minimally-processed, whole foods such as nuts and vegetable and olive oil (which has some saturated fat), as well as fish, fruits, vegetables and small portions of animal products such as yogurt and cheese. (Surprisingly, the health-promoting Mediterranean style diet is made up of about 45 percent of calories from fat, including small amounts of meat)

So, if you’re still asking the question, is saturated fat good or bad? The answer, Mozaffarian says, depends on what you’re eating instead. He points to another study that found replacing saturated fats with carbohydrates has no benefits.

Now, of course, not everyone is convinced by the new studies that question the link between saturated fat and heart disease. Groups including the World Health Organization and the American Heart Association promote a low-intake of saturated fat.

And, vegan groups do as well. “I think there is support for removing all animal products from the diet for health purposes,” says Susan Levin of the Physicians Committee for Responsible Medicine, which advocates vegan diets.

She points out that two population studies (an Adventist Health Study and a European Prospective Investigation into Cancer and Nutrition [EPIC] study) have shown that the fewer animal products you consume, the less likely you are to have diabetes or to be overweight.

Some argue, that the type of fatty acids that make up the saturated fat in a food makes a difference, too. For instance, recent studies suggest the fatty acids in milk and yogurt may be beneficial for heart health. And as we’ve reported, researchers are actively studying this full fat dairy paradox. But processed red meats, also high in saturated fat, are shown to increase the risk of heart disease and certain cancers.

So, saturated fat isn’t automatically the bad guy—and shouldn’t be demonized, these researchers say. It’s just one part of the complex dietary puzzle.

Experts say, remember this big picture : Too many calories from any source, whether it’s fats or carbohydrates, can lead to weight gain. And it’s that extra weight that increases the risk of heart disease.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

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