In the 1980s, fat was demonized as causing heart disease and obesity. Now, scientists understand that there are different kinds of fats, and some dietary fat is essential for proper nerve activity, immune system function and healthy cells. Fat also helps absorb vitamins A, D, E and K from food. These days, we understand that there are “bad” (saturated and trans) fats and “good” (monounsaturated and polyunsaturated) fats. The USDA recommends that fat (good or bad) make up no more than 25 to 30 percent of our daily calorie intake.
“Good” Fat or “Bad” Fat?
Foods generally contain a mixture of fats, but selecting foods that are rich in monounsaturated and polyunsaturated fats instead of trans and saturated fats helps lower your risk of many diseases. A good rule of thumb for distinguishing healthy fats from disease-promoting saturated and trans fats is to ask yourself if it comes from a plant, an animal or a laboratory. With a handful of exceptions saturated fats come from animal sources, so replace high-fat animal products like cheese and fatty meats with plant fats like nuts and avocados. Another way to tell the good from the bad is that hydrogenated (“trans”) and saturated fats are solid at room temperature, while healthy fats remain liquid. Hydrogenated fats were once healthy oils which have been chemically altered to behave like saturated fats. In recipes, replace spreadable fats like butter and margarine with healthier canola or olive oil. Reading nutrition labels gives you a better idea of your food’s fat composition. Look for foods without saturated fat and avoid the word “hydrogenated” in the ingredients list.
Polyunsaturated Fats
Omega-3 and omega-6 fatty acids (also known as “essential fatty acids” or EFAs) are the most familiar forms of polyunsaturated fats. EFAs are essential to proper brain function, healthy hormonal levels and smooth nerve activity in the body. Polyunsaturated fats promote cardiovascular health by lowering LDL (“bad”) cholesterol levels in the blood, but also lower HDL (“good”) cholesterol.
Scientists at the American Society for Clinical Investigation and at the Department of Clinical Sciences in Sweden have correlated high levels of omega-6 fatty acids with a higher incidence of prostate and breast cancer. Omega-6 fats are also linked to heart disease. To lower your risk of these serious conditions, replace omega-6 fatty acids (which are common in western diets) with omega-3 fats. Omega-3s are found in fatty, cold water fish (salmon, mackerel), fish oil supplements, plant oils (grape seed, flax, hemp), walnuts and seeds (sunflower, poppy, chia).
Monounsaturated Fats
Monounsaturated fats are often considered the healthiest fats because, according to a study lead by Dr. Alicja Wolk of the Karolinska Institute in Stockholm, replacing unhealthy fats with monounsaturated fats may decrease the risk of breast cancer. Monounsaturated fats are rich in vitamin E, an antioxidant which is good for the skin. They also lower LDL (“bad”) cholesterol and raise HDL (“good”) cholesterol in the blood. Foods with high concentrations of monounsaturated fats include nuts (hazelnuts, almonds, Brazil nuts, cashews), peanuts, seeds (sesame, pumpkin), avocados and some oils (olive, rapeseed, canola).
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