Alternative Names monounsaturated fat, polyunsaturated fat
Definition
No fat in food is completely saturated or completely unsaturated. Most foods have a mixture of all types of fat. For ease in classifying a food, the prominent fat is recognised.
Fat is needed by the body in small amounts for important functions. Some dietary fats are healthier than others. Unsaturated fats are healthier than saturated fats. Most unsaturated fats come from plant sources. These types of fats are heart-healthy and a good source of essential fatty acids.
What food source is the nutrient found in? Unsaturated fat can be either monounsaturated or polyunsaturated. These fats come mostly from plant sources and are liquid at room temperature.
Foods high in monounsaturated fat include avocados, olives, peanuts and most nuts. Canola, olive, and peanut oils are also high in this type of fat.
Foods high in polyunsaturated fat include soft margarine, mayonnaise, salad dressing, most nuts, and some seeds. Oils made from corn, cottonseed, safflower, sunflower, grape seed, sesame, and soybean are also high in this kind of fat. Fish contains a type of polyunsaturated fat called omega-3 fatty acids. Omega-3s are termed essential fatty acids because the body cannot make them, and they must be obtained from the diet.
Trans fats are created when an unsaturated fat like vegetable oil is hydrogenated. Hydrogenation is a process that makes the fat solid at room temperature. It also gives it a shape like saturated fat. Hard cooking margarine and vegetable shortenings are examples of hydrogenated products. Trans fats also occur naturally in beef, pork, lamb, butter, and milk.
How does the nutrient affect the body? Both kinds of unsaturated fat can be used in place of saturated fat in the diet. They help to lower levels of total and LDL cholesterol in the blood. LDL cholesterol is low-density lipoprotein cholesterol, the "bad" type of cholesterol.
Monounsaturated fat may be better than polyunsaturated fat, when lowering LDL and increasing HDL cholesterol. HDL cholesterol is high-density lipoprotein cholesterol, the "good" type of cholesterol.
Polyunsaturated fats supply essential fatty acids (EFA's). Fish are high in these essential fatty acids. EFA's are needed for normal growth and development in children, and for healthy skin. EFA's are vital to the human brain and central nervous system. They also produce hormone-like substances that help regulate blood pressure, blood clotting, and the immune system. Essential fatty acids tend to decrease LDL ("bad") cholesterol and decrease blood triglyceride levels. High levels of both of these are linked to heart disease. Trans fat tends to raise total and LDL cholesterol levels like saturated fat does. In very high amounts, it may even lower HDL cholesterol levels.
Information Total fat intake should be 30 percent of total kilojoules for the day. Most experts agree that about 20 percent of total fat kilojoules each day should come from a combination of the two unsaturated fats. The remaining 10 percent can come from saturated fats.
Here are some tips for a heart-healthy diet:
Eat fewer processed snacks and sweets, including cakes, biscuits, and pastries. These contain partially hydrogenated oils, which means that trans fats are present.
Use unsaturated oils, margarines, and spreads in place of saturated fat products, such as butter or hydrogenated shortening. Check labels on oils and margarines for amounts of saturated, polyunsaturated and monounsaturated fats.
Snack on small amounts of nuts and seeds 2 or 3 times per week. Limit serving sizes to a couple of tablespoons.
Eat more fish. About 225 grams of fish per week, or two meals, can reduce the risk of heart disease.
Eat lean meats and skinless poultry. Choose meats already trimmed of fat. Trim visible fat from meats before cooking. New fashioned pork, trim lamb, lean beef are examples of butcher lean meats.
Eat at least seven servings of fruits and vegetables each day.
Incorporate more plant foods into the diet such as beans, whole-grain foods and soy products. This will also help to increase fibre intake.
Author: Sandy Keefe, RN, MSN Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
