The Truth About Fats

Not all fats are equal. Learn which ones actually boost your health!

From the WebMD Archives

For years, fat has been the bogeyman of bad health. Increasingly, however, research is showing that not all fats are equal. Some oils and fatty foods contain chemicals called essential fatty acids, which our bodies need for good health. How do you know the difference between good fats and bad fats? Read on!

"We've had such emphasis on eating low-fat foods," says Patricia Kendall, PhD, RD, a professor at the Colorado State University Cooperative Extension Office. "But all these new studies on oils and high-fat foods like nuts and cold-water fish show we've been ignoring how much we need certain fats."

The two essential fatty acids most important to good health are omega-3 and omega-6. But we need these in the right balance in order to protect our hearts, joints, pancreas, mood stability, and skin.

Unfortunately, we eat way too much omega-6, which is found in the corn oil and vegetable oils used in so much American food. Too much omega 6 can raise your blood pressure, lead to blood clots that can cause heart attack and stroke, and cause your body to retain water.

We don't eat nearly enough omega-3, which can reduce our risk for heart disease and cancer. Omega-3 is found in fish and fish oil, all green leafy vegetables, flax seed, hemp, and walnuts.

How Much Fat Do You Really Need?

Most experts recommend that we get 30% of our calories from fat, although we can survive fine on as little as 20%, even 10%. If you're like most of us, you're getting plenty of fat - most Americans consume about 40% of their calories from fats in meat, butter, cheese, baked goods, etc.

The better question to ask is, "Are you getting the enough of the right fats?" says Ruth Kava, PhD, RD, of the American Council of Science and Health. "Most of us get too much fat, and too much unhealthy fat," she says.

Making the Switch

To make the switch to heart-healthy fats, start by avoiding the truly unhealthy fats - trans fatty acids. These trans fats come from vegetable oils that were chemically modified so they are solid like butter. Because these oils don't spoil as quickly as butter, they are used in most packaged cookies, chips, crackers and other baked goods sold in the supermarket, as well as in margarines.

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The solidifying process - called hydrogenation - extends the shelf life of food, but it also turns polyunsaturated oils into a kind of man-made cholesterol. Trans fats can increase your level of "bad" LDL cholesterol, and may increase your risk of heart disease. What's more, these man-made fats are taken up by the body much easier than are omega-3s. So trans fatty acids not only harm your health, they also block the absorption of healthy fats.

"How bad trans fats are for you depends on how much you eat," says Kava. "Trans fats can raise your blood cholesterol as much as excess cholesterol (from the diet) can in some people."

To avoid trans fats, look on the nutrition label of packaged foods. They'll appear on the ingredients list as "hydrogenated" or "partially hydrogenated" vegetable oils. If you can, switch to products that don't use hydrogenated oils. The baked goods won't last quite as long in your pantry, but your body will benefit.

Now for the good news: There are some fatty snacks that actually boost your health!

Go Nuts

Nuts are the latest high-fat food to undergo a change in dietary reputation.

"It doesn't seem to matter what nuts you eat to get important benefits, as long as they don't have added oil and salt," says Kendall.

The latest pro-nut research is out of the Harvard School of Public Health. Researchers found that women who reported eating a half serving of peanut butter or a full serving of nuts five or more times a week showed as much as a 30% reduced risk of developing type 2 diabetes. And the findings go on.

Other nuts, including almonds, walnuts, and pecans, have been shown to have heart healthy benefits, including lowering "bad" LDL cholesterol. (Remember, walnuts are also a source of omega-3.)

Nuts to Avoid

There really aren't any unhealthy nuts, as long as you leave out the oil and salt. But it's important to remember that all nuts are high in calories.

"You can't just add them to your diet," says Kendall. "You really need to think about using them to replace empty calories. Think about them as excellent substitutes for junk food."

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Bring on the Fish

For a while now, cold-water species of fish such as salmon, tuna, trout, striped bass, sardines, and herring have taken the spotlight as the best protein-rich food source because they are loaded with omega-3 fatty acids. Studies show that people who eat such fish two times a week have less heart disease, a reduced risk of cancer, and improvements in mental health, particularly in mood function.

But there's a caveat.

"I'm also concerned about the mercury that these species of fish can carry for pregnant women," says Kava. She recommends that pregnant women stay away from shark, swordfish, and king mackerel because these bigger species tend to present more of a risk.

If you're not pregnant but still concerned, Kava says small salmon species give the most benefit with the least exposure to mercury.

Animal Fat to Avoid

We've long been told to eat less red meat, but new long-term studies of how eating habits affect actual health measures do not bear out many of the popular myths.

"People want to hear that not eating less red meat will save them, but that is a simplistic notion that doesn't really fit in with modern nutrition science," says Kava. "What the science tells us is that lifestyle changes -- stopping smoking, getting regular exercise, limiting alcohol intake, increasing vegetable intake -- has by far the most pronounced effect in improving a person's health than does cutting out certain food categories."

This does not mean you should eat steak every night. If you're at high risk of heart disease, you should still severely limit your saturated fats. But the newer research does explain why many health organizations no longer try to scare people away from "bad" foods.

For example, says Kendall, "for years, we've encouraged people to eat poultry instead of red meat because it is lower in saturated fat. But when you look at the data on how these foods affect actual blood cholesterol levels, there isn't that much difference."

Rather than avoid meats, nutritionists today say you should simply eat more of the foods proven healthy in long-term studies: fish, vegetables, and fruit. Equally important, exercise, even you just walk briskly 30 minutes a day.

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The Good Oils

The health message about oils has not changed and is very simple. Stick to olive oil or canola oil.

Olive oil is loaded with monounsaturated fatty acids, which do not raise blood cholesterol levels. It also is a good source of vitamin E and polyphenols, which act as antioxidants, reducing the oxygen-related damage to the vascular system.

Canola oil, on the other hand, has loads of monounsaturated fatty acids in the form of oleic acid. This acid has been shown to reduce blood cholesterol levels, and it may lower LDL, or "bad," cholesterol levels without changing "good" HDL levels. Also, canola oil is high in two essential polyunsaturated fatty acids that our bodies can't make: alpha-linolenic acid and linolenic acid.

Alpha-linolenic acid appears to lower blood triglyceride levels. It also may reduce platelet aggregation and increase blood clotting time, both of which are important to people at risk of heart disease and stroke.

Oils to Avoid

Simply put, avoid vegetable oils that are high in omega-6 fatty acids, such as regular vegetable oil, corn oil, safflower oil, soybean oil, and cottonseed oil.

Good Spreads

Until the recently, there really were no healthy spreads. Butter is too high in cholesterol for people who are at risk of heart disease; most margarine is made from trans fatty acids. In the 1980s, some manufacturers put out special, watered-down versions of spreads that had lower overall calorie content, but they tasted like it.

Then came spreads made from olive oil, wood pulp (Benecol) and soybeans (Take Control), which include chemicals that actually help your heart's health.

"Spreads like Benecol, which are made from plant stanol esters, are lower in trans fat than regular margarine and have been shown to lower the risk of heart disease," says Kendall. They especially help people taking statin drugs to lower their blood cholesterol levels. "But," she adds, "they are more expensive, too, so if you are at risk of heart disease, they may be worth the price."

Kendall suggests doing what the Italians do -- put olive oil on your bread. Or, you could make what she calls "better butter."

Blend one part olive or canola oil with one part butter," Kendall says. It makes a softer spread and dilutes the cholesterol with monounsaturated fats.

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Spreads to Avoid

Remember, traditional margarine is a trans fat nightmare. Check the ingredients list and avoid spreads that are made of "hydrogenated" or "partially hydrogenated" oils.

WebMD Feature Reviewed by Louise Chang, MD

Sources

Sources: Patricia Kendall, PhD, RD, professor, Colorado State University Cooperative Extension Office * Ruth Kava, PhD, RD, American Council of Science and Health * Artemis Simopoulos, MD, editor in chief, World Review of Nutrition and Dietetics * The PDR Family Guide to Nutrition & Health.

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