Healthy Fats and Oils
In this section, you will learn how excess fat comes into the diet and also how different fatty acid sources have different effects on physiological processes.
Fats and oils provide the most concentrated source of calories of any foodstuff. The vast majority of the fats you eat and store are called triglycerides. This name comes from the fact that triglycerides are made up of three fatty acids on a carbon backbone.
Fat and Oil Sources
The principal dietary sources of fat are meats, dairy products, poultry, fish, nuts, vegetable oils and fats used in processed foods. Vegetables, fruits and grains contain only small amounts of fat. Vegetable oils are pure fat only as a result of the processing of plants. The most commonly used oils and fats for salad oil, cooking oil, shortening and margarine in the United States include:
- Canola (low erucic acid rapeseed oil),
- Palm kernel
These fats and oils contain varying compositions of fatty acids that have particular physiological properties.
Essential Fatty Acids
Fats provide two essential fatty acids, linoleic and linolenic acids. These two fatty acids are made by plants but not by humans, so we need to get them from our diet, while vegans obtain these two essential fatty acids by eating plants, which are about 10 percent fat calories. These fatty acids, which are necessary to maintain life, need to be present at a very small percentage (five to 10 percent) of total calorie intake. Fats carry fat-soluble vitamins and concentrate the tastes of foods to make them more palatable. Wherever there is food scarcity, fats are good as they are compact calories. The body stores 95 percent of excess calories as fat, and there are 130,000 to 160,000 calories stored in the body fat of a normal weight individual.
Omega-3 for Balanced Nutrition
An examination of the numerous studies on fish oils suggest they may have many benefits. However, these studies simply provided supplementation of fish oils without regard for the existing excess body fat or the underlying diet rich in n-6 (omega-6) fatty acids. Therefore, the novel approach of draining the body fat of n-6 through a low-fat diet and then adding back small amounts of n-3 (omega-3) is a key component of balanced fat nutrition. Omega-9 oils, such as olive oil and high oleic acid sunflower oil, can be added to the diet without affecting the benefits of omega-3 fatty acids. However, all fats, regardless of the source, have nine calories per gram or more than 135 calories per tablespoon. So they must be used in moderation as needed to enhance taste and texture of foods.
The Impact of Food Industrialization
The industrialization of the food supply, which began more than 400 years ago, accelerated in the last 50 years due to strong agribusiness subsidization by the United States and other governments. The desire for populations to eat more meat products as their wealth increased also played an important role in changing the food supply and dietary patterns. Special grain varieties, such as hybrid corn, were developed for feeding livestock efficiently. A by-product of the overproduction of grains has been the popularization of refined vegetable oils in cooking and processed foods. Even rural areas of China, where the economic boom has not yet been fully realized, have increased their intake of refined vegetable oils rich in omega-6 fatty acids and poor in omega-3 fatty acids.
The ratio of omega-6 to omega-3 in corn oil is 57-to-1, while in soybean oil it is 57-to-8 (or about 7-to-1). As the public became more aware of the problem, some companies produced higher contents of omega-3 short-chain fatty acids, such as canola oil, which has a 21-11 ratio (less than 2-to-1). But canola oil still contains large amounts of omega-6 fatty acids. In contrast, fish oils are a concentrated source of omega-3 fatty acids with very little omega-6 fatty acids.
Omega-9 rich fats, such as olive oil and high oleic safflower oil, do not affect the balance of omega-3 and omega-6 fatty acids. By increasing these fats in the diet, it is possible to reduce refined carbohydrates and add taste. However, these fats need to be used in moderation as a single tablespoon of fat adds more than 135 calories to the diet. Using fats sparingly by spraying them onto non-stick cooking pans and reducing their use in baked goods are good ways to maintain taste while cutting unnecessary calories.
Evolution and Omega-3
This situation has been further aggravated by the corn feeding of livestock so that the proportion of short-chain fatty acids from two competing families called omega-3 and omega-6 have been drastically changed from what they were in the plants on which mankind evolved 50 to 100 thousand years ago. Today, grass-fed beef has a different fatty acid profile than corn-fed beef. Hidden fats in cooking and vegetable oils also contribute more omega-6 fatty acids to beef during preparation. It has been estimated that the modern Western diet is deficient in omega-3 fatty acids with a ratio of omega-6 to omega-3 of 15/1-to-16.7/1, instead of 1-to-1 as is the case with wild animals and, presumably, ancient human beings who lived in nutritional equilibrium.
Recent studies in mice have indicated an interrelation between energy balance, diet, and the composition of the gut bacteria.
The Fitness Textbook will teach you the basic principles of human performance nutrition, including muscle metabolism and fuel utilization before, during and after exercise.