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Understanding the unsaturated fats

Confused about fats? Learn the latest on which fats offer the best health benefits.

There used to be one simple rule—all fat is bad. More recently, we’ve been told that fat is absolutely essential to our health, especially polyunsaturated fats in plant-derived oils. But, as research piles up, the picture of fats and health has sometimes become blurred.

The role of polyunsaturated fats

Polyunsaturated fats include two types: omega-3 (linolenic acid) and omega-6 (linoleic acid). Both are essential and not made by the body. “For years the recommendation has been to replace saturated fat from animal sources with polyunsaturated fat from plant sources,” says Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health. But a research analysis published last year threatened to turn that advice on its ear. The study suggested that polyunsaturated fats, primarily found in vegetable oils, were not necessarily protective against heart disease. In particular, the role of the omega-6 fatty acids was called into question. Some investigators went as far as to speculate that omega-6s might actually promote inflammation leading to arterial disease.

To help clear up the controversy, Dr. Hu and his colleagues undertook an extensive review and analysis of research done on the relationship between linoleic acid (the main type of omega-6 fat) and the risk of coronary artery disease. The results were convincing: the individuals who consumed the most linoleic acid each day had a 14% lower chance of having a heart attack or other cardiac event than those who had the lowest daily intake. In addition, they were 17% less likely to die of heart disease.

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Olive oil, avocados, salmon, seeds, and nuts are rich in healthy unsaturated fats.

Getting the right omegas

Fortunately, foods rich in omega-6 are abundant in our diet, so you usually do not need supplements, says Dr. Hu. He recommends getting 5% to 10% of your daily calories from sources such as corn oil, safflower oil, sunflower oil, soybean oil, canola oil, sesame seed oil, and walnuts.

Omega-3 fat, a polyunsaturated fat found in both animal and plant sources, is equally important to good heart health. It also helps to drive normal brain and nervous-system development and function, immune function, blood flow, heart rhythm, and healthy skin. The most active omega-3 fatty acids are known as
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These can be directly obtained from marine animals and algae. Eating several servings of fish a week will supply you with enough of these nutrients. Another type of omega-3 fat, called alpha-linolenic acid, comes from soybean and canola oils, walnuts, flaxseed, and green leafy vegetables.

Don’t forget the monounsaturated fats

A rising star in the universe of heart-healthy fats is olive oil, which is rich in monounsaturated fat. When substituted for saturated fat, monounsaturated fats help lower your “bad” LDL cholesterol. The antioxidant and anti-inflammatory properties of extra-virgin olive oil add benefits beyond lowering cholesterol. Olive oil is particularly high in monounsaturated fatty acids, containing about 75% by volume. Other good sources include avocados, peanuts and peanut butter, and tree nuts. Also, many types of vegetable oils include a mix of omega-6, omega-3, and monounsaturated fatty acids. A good target is to obtain 15% to 20% of your daily calories from monounsaturated fat.

Trans fat remains bad fat

Throughout the fat debate, one piece of advice remains constant: avoid trans fats. Trans fat is made when vegetable oil is heated in a process known as hydrogenation to make it more stable and less likely to spoil. Trans fats are the “triple whammy” of fats because they raise your LDL cholesterol and lower your “good” HDL cholesterol, as well as increase artery-damaging inflammation. To reduce trans fats in your diet, read food labels and look for the words “partially hydrogenated oil.” It’s the manufacturers’ term for trans fat. You can also lower your trans fat intake by staying away from commercially prepared baked goods and fried foods.

A balancing act

The best strategy, says Dr. Hu, is to aim for an overall balance in your diet. “There is convincing evidence that you can lower your risk of heart disease by replacing saturated fats and refined carbohydrates in your diet with vegetable foods containing unsaturated fats,” he says. “But it would be a good idea to get a mixture of polyunsaturated and monounsaturated fats rather than only one type. Also, the focus should be on optimizing types of fat rather than reducing total amount of dietary fat.” 

Posted by: Dr.Health

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