Fat serves vital purposes in the diet because it contains several important vitamins and aids the absorption of other essential nutrients, including essential fatty acids, carotenoids, and fat-soluble vitamins. Fat in foods stimulates the gallbladder to contract as the food from a meal reaches the intestines. The bile that the gallbladder squirts into the digestive tract is needed to digest and absorb food.
The body requires fat from foods in order to function properly. In its most recent report, the Institute of Medicine (IOM) recommended that 20% to 35% of daily calories come from fat. For the first time, it also recommended specific amounts of two essential fatty acids: linoleic acid, an omega-6 fatty acid in vegetable oils, and alpha-linolenic acid, an omega-3 fatty acid in fatty fish. These fats are considered essential because the body is unable to produce them on its own.
FAT-CONTAINING NUTRIENTS ESSENTIAL FOR GOOD HEALTH
Nutrients Essential Fatty Acids Fat-Soluble Vitamins Carotenoids
Examples Linoleic, alphalinolenic Vitamins A, D, E, K Beta-carotene, lycopene, lutein
What They Do Involved in regulating the body’s inflammation, blood clotting, and cholesterol systems Involved in all body functions, but particularly in tissues like the bones, eyes, blood, and skin; vitamin E is an antioxidant Antioxidants— substances that work against the breakdown in body functions linked with the development of conditions like heart disease
Good Sources Nuts, grains, seeds, some oils Eggs, whole grains, nuts, oils, meat and fatty fish, vegetables that are colorful (e.g., red, orange, dark green) Fruits and vegetables that are colorful (e.g., red, orange, dark green)
In recent years, a great deal has been learned about fat. Different kinds serve different functions in the body, and it is often the balance between fats that makes the difference. The Mediterranean diet is an example of a higher-fat but balanced-fat diet. People who eat the Mediterranean-style diet of fruits, vegetables, fish, legumes, breads and cereals, and olive oil have a lower risk of heart disease and certain cancers. The actual amount of fat eaten in a Mediterranean diet is not low, but it is associated with positive health at least in part because of the mix of the fats it contains.
With this new understanding about the role of fats in health, in the most recent edition of the Dietary Reference Intakes, the IOM liberalized its recommendation of the percent of fat in a balanced diet. The maximum recommended percentage of calories coming from fat was increased from 30% to 35%. This revised recommendation gives greater flexibility for eating more fat in the diet, provided the fats one eats include more unsaturated sources. Eating more saturated or trans fats is never recommended for good health.
Eating too little fat can cause problems. A very low-fat diet does not stimulate the gallbladder to contract and empty its bile, increasing the risk of gallstone formation. Most very low-fat diets are high in carbohydrates. A high-carbohydrate diet can increase triglycerides in some people. For this reason, very low-fat diets for weight loss are not recommended by either the American Heart Association or the American Diabetes Association. Very low-fat diets are too low in several nutrients, including vitamin E. This is particularly noteworthy because the increasing need for this vital nutrient has been recognized for its role as an antioxidant. The latest edition of the Dietary Reference Intakes increased the recommended daily amount of vitamin E from 8 milligrams for women and 10 milligrams for men to 15 milligrams for both men and women.
0 comments: