In reality, dozens of fats are common in the diet, and each one has a different role in the body and effects on your health. Even within groups of fats like saturated, unsaturated and polyunsaturated, specific fats still have different roles.
This article will explain the differences between some of the main dietary fats and their health effects, both good and bad. The key is to understand that each type of fat has its own unique effects on the body. Decades ago, common sense was to eat fatty foods because it was the most efficient way to get energy. Fat contains more calories by weight than any other nutrient. Over time, scientists began to understand that some fats are healthier than others.
In the s, Russian scientists found that feeding animals very high-cholesterol diets caused atherosclerosis 1. This is a condition where plaque builds up in the arteries, narrowing them and increasing the risk of heart disease.
Atherosclerosis is the most prominent cause of heart disease and stroke 1. Many attributed this phenomenon to wartime rationing in World War II. This fueled the belief that fat and cholesterol, which were high in the restricted foods, contributed to heart disease. The Seven Countries Study, a large international study directed by American physiologist Ancel Keys and other international scientists, revealed several important risk factors for heart disease.
These included smoking, high blood pressure, weight gain, yo-yo dieting and blood cholesterol 2. The Seven Countries Study contributed to the hypothesis that saturated fat increased blood cholesterol, predicting atherosclerosis and heart disease 3. However, even decades ago Ancel Keys recognized not all fat is harmful. He was skeptical of the importance of dietary cholesterol and showed unsaturated fats reduce the risk of heart disease 4.
This article will demystify the confusing literature on fat by looking at a combination of old and new research. Since the s, scientists have suspected that fat and cholesterol could cause atherosclerosis, heart disease and stroke.
However, later research has shown that judging all fats together — even all saturated fats — is an inaccurate oversimplification. Cholesterol is made by the liver in humans and animals. For this reason, you only get it in your diet from animal products. The main sources include egg yolks, animal liver, fish or fish oil, animal fats or oils such as butter, shellfish, meat, cheese and baked goods made with animal fat. The liver adjusts the amount of cholesterol it makes depending on how much comes in from the diet.
When you eat large amounts of cholesterol, the liver makes less. Cholesterol you eat has a small effect on cholesterol levels in your blood. Even 50 years ago, Ancel Keys recognized this effect was trivial for most people. According to a large study that combined evidence from more than , adults, dietary cholesterol was not associated with heart attack or stroke 6.
Dietary cholesterol does not change the risk of heart disease for most people, according to the largest studies available. Saturated fat is different from unsaturated fat in that it has no chemical double bonds.
This makes it more stable, so it is solid at room temperature. Am J Clin Nutr , Appel, L. JAMA , Department of Agriculture, U. Government Printing Office. Dietary Guidelines for Americans, , Lichtenstein, A.
Circulation , Institute, N. Population, — Siri-Tarino, P. Micha, R. Mozaffarian, Saturated fat and cardiometabolic risk factors, coronary heart disease, stroke, and diabetes: a fresh look at the evidence. Lipids , Astrup, A. Riserus, U. Willett, and F. Visit www.
Good Fats www. It features recipes and various tools, including a shopping list, label-reading guide, fact sheets, and a chart identifying the sources and properties of omega-3, -6, and -9 fatty acids. In addition, the site provides heart-healthy Mediterranean-style recipes.
Commodity boards such as the following offer various handouts, recipes, and other information about healthy fats:. References 1. Dietary Guidelines for Americans, Effects of monounsaturated fatty acids on cardiovascular risk factors: a systematic review and meta-analysis. Ann Nutr Metab. Liu X. Effects of canola oil and high oleic canola oil-rich diets on abdominal fat mass in individuals at risk for metabolic syndrome. Facts about polyunsaturated fats. Omega-3 fatty acids are good for your heart in several ways.
Check the total fat in one serving. Be sure to add up the number of servings you eat in one sitting. Look at the amount of saturated fat and trans fat in a serving -- the rest is healthy, unsaturated fat.
Some labels will note the monounsaturated and polyunsaturated fat contents. Some will not. Make sure most of your daily fats are from monounsaturated and polyunsaturated sources. Many fast food restaurants also provide nutrition information on their menus. If you do not see it posted, ask your server.
You also may be able to find it on the restaurant's website. Foods and oils with higher amounts of polyunsaturated fats include: Walnuts Sunflower seeds Flax seeds or flax oil Fish, such as salmon, mackerel, herring, albacore tuna, and trout Corn oil Soybean oil Safflower oil To get the health benefits, you need to replace unhealthy fats with healthy fats.
Eat walnuts instead of cookies for a snack. But be sure to keep your portion small, as nuts are high in calories. Replace some meats with fish.
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