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Fats in the diet: Healthy or not?

Saturated Fats

Remember the low-fat craze in the 1990s, when grocery stores couldn’t keep their shelves stocked with fat-free cookies and we gave up egg yolks for egg whites?

The newest U.S. Dietary Guidelines, released earlier this year, now confirm that fats aren’t the enemy to good health that we once believed.

However, some fats are more beneficial to heart health than others. The new guidelines still recommend limiting saturated and trans fats in the diet, says Ruth Litchfield, associate professor and associate chair of Iowa State University’s Department of Food Science and Human Nutrition.

“Regardless of the dietary guidelines, the message has always been moderation,” Litchfield says. “Just as long as you are not going to extremes in any direction, plus or minus, but a variety in your diet — a variety of fruits and vegetables, a variety of grains, a variety of protein sources. And ‘in moderation’ is really still the mantra.”

One of the biggest changes in the latest U.S. Dietary Guidelines is that they no longer set a limit for cholesterol intake.

The latest research shows that dietary cholesterol doesn’t impact blood cholesterol levels, Litchfield explained. Common sources of cholesterol in the U.S. diet include whole eggs, meats and dairy foods.

So Americans don't need to limit their consumption to just one egg per day or to eat just the egg whites, not the yolks, which contain cholesterol.

“From a professional standpoint, that didn’t surprise me,” says Litchfield about the new cholesterol recommendation. “For those of us who work in the (nutrition) area and are familiar with the research, this is something we have seen for the past 10 years. But now there is enough scientific base that they can take away that restriction on cholesterol.”

The new dietary guidelines also aren’t as restrictive on fats. Now the guidelines say that up to 35 percent of our daily calories can come from fats, compared to 30 percent in previous guideline recommendations, Litchfield says.

“We are no longer in the ‘lower the fat, the better’ (era),” she says. “We have learned that getting fat (intake) as low as possible is not in our best interest. The overarching goal is not to decrease total fat as much as possible, but really to optimize the type of fat.”

The U.S. Dietary Guidelines still recommend that no more than 10 percent of daily calories come from saturated fats. Primary sources of saturated fat include red meats, poultry and full-fat dairy foods, such as butter and whole milk.

Research has found that for every 1 percent reduction of calories from saturated fat in the diet, there is a 2 to 3 percent reduction in the risk of coronary heart disease, Litchfield says.

Unfortunately, during the low-fat craze in the ‘90s, Americans tended to replace all fats in the diet with carbohydrates, she explains.

But replacing saturated fats with carbohydrates increases unhealthy triglycerides and decreases HDL, or the “good,” cholesterol in the bloodstream, so it poses a greater risk to cardiovascular health, Litchfield says.

“What we now know is as we try to decrease saturated fat, we actually don’t want to replace it with carbohydrates,” Litchfield says. “The preference is to replace (saturated fat) with polyunsaturated fats, which would come from corn oil, safflower oil, soy oil. That decreases coronary heart disease the most.”

Polyunsaturated fats are also found in fatty fish like salmon, mackerel and trout, as well as some seeds and nuts, including flax, walnuts and sunflower seeds, Litchfield says.

However, Litchfield stresses that limiting saturated fats doesn’t mean that you should eliminate red meats and dairy from your diet. The new dietary guidelines recommend consuming proteins from all sources — plant and animal — in moderation.

In the U.S. Department of Agriculture’s “MyPlate” recommendations, proteins should fill a little less than one-fourth of your plate. One-half of the plate should be fruits and vegetables, and about one-fourth of the plate should be grains, preferably a whole grain. MyPlate also includes a serving of low-fat or fat-free dairy, including milk, yogurt, cheese or fortified soy beverage.

“Red meat — pork and beef — can fit into a healthy diet as long as it’s a leaner cut and it’s an appropriate portion size,” Litchfield says.

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