The truth about dietary fat

For years, experts recommended low-fat diets as a way to lower cholesterol and heart disease risk. Today, we know that low-fat isn't the way to go after all. A healthy diet includes plenty of "good-for-you" fats — and limits the unhealthy ones. Current dietary guidelines recommend that you get 20% to 35% of your daily calories from fat. Even more may be fine, if you follow these simple guidelines.

Favor the "good" fats

The best sources of healthy fats are oily, cold-water fish, such as salmon and tuna; plant sources such as avocados and nuts; and vegetable oils, such as olive, canola, soybean, and cottonseed oils. These fats promote heart health because they lower cholesterol levels — and they may even fight chronic inflammation, which may contribute to heart disease.

It's okay to get up to 35% of your daily calories from fat — as long as most of it comes from sources like these.

Limit saturated fats

Typical sources of saturated fat include animal products, such as red meat, whole-fat dairy products, and eggs, and also a few vegetable oils, such as palm oil, coconut oil, and cocoa butter. Saturated fat can increase your levels of "bad" LDL cholesterol. But it has some benefits, too — it lowers triglycerides and nudges up levels of "good" HDL cholesterol.

The role of saturated fat in heart disease is currently under debate. For now, it's best to limit your intake of saturated-fat-rich foods.

Avoid trans fats

Trans fats are found in many commercial baked goods, processed foods, solid margarines, and deep-fried restaurant foods. These fats have no nutritional value — and we know for certain they are bad for heart health. Trans fats increase LDL cholesterol and triglyceride levels while reducing levels of HDL cholesterol.

Recently, the FDA banned trans fats from the U.S. food supply. The phasing-out process is expected to take three years. The encouraging news is that many major food suppliers and restaurants have already substituted healthier fats for trans fats.

To learn more about good and bad fats and other factors that contribute to your cholesterol levels, buy Managing Your Cholesterol, a Special Health Report from Harvard Medical School.