The human body requires three types of nutrients, known as macronutrients, to support daily function, growth and development: carbohydrates, protein and fat. Although most people believe they should avoid consuming dietary fat, fat performs vital functions. These include promoting the absorption of fat-soluble vitamins, facilitating the production of hormones and providing structure to cell membranes. Some types of fat, including polyunsaturated fat, provide essential fatty acids known as omega-3 fatty acids.
Polyunsaturated Fat
All fats share the same basic chemical structure, but slight variations affect the general properties of a fat and how it affects the body. In general, adults should consume between 20 and 35 percent of their daily calories as fat. To ensure you get the daily dosage of specific fats, like omega-3 fatty acids, and to promote a healthy cardiovascular system, you must pay attention to the type of fat you consume. The three main types of fat are saturated fat, trans fat, and unsaturated fat, which includes both monounsaturated and polyunsaturated fat. Saturated fats and trans fat negatively affect blood cholesterol levels, so the American Heart Association suggests limiting your daily intake to less than 7 percent and less than 1 percent, respectively. Because the unsaturated fats help you lower blood cholesterol levels, they should make up the majority of your fat intake. The polyunsaturated fats consist of two types of important fatty acids, omega-6 and omega-3.
Omega-3 Dosage
Chemically, omega-3 fatty acids are polyunsaturated fats in which the first chemical bond occurs between the third and the fourth carbon atom. The average person doesn't care about this slight chemical difference, but how the fat affects the body is important. Omega-3 fatty acids play a vital role in brain function and in promoting normal growth and development. The human body lacks the enzyme necessary to make the omega-3 fatty acid known as alpha-linolenic acid, or ALA, making this an essential fatty acid you must consume from food sources. For those who get the proper dosage of ALA, the body can convert ALA into the other two omega-3 fatty acids, known as docosahexaenoic acid, or DHA, and eicosapentaenoic acid, or EPA. The Institute of Medicine sets the adequate intake based on the amount believed to meet the needs of men at 1.6 g per day and of women at 1.1 g per day. It also sets the acceptable macronutrient distribution range -- the range of ALA intake associated with a reduced risk of chronic diseases -- at 0.6 to 1.2 g per day for all adults.
Food Sources
The typical diet consumed by Americans fails to meet the omega-3 daily requirement. For this reason, the American Heart Association recommends eating two 3.5 oz. servings of fatty fish per week. Fatty fish, like salmon, tuna and herring, serve as a good source of EPA and DHA omega-3 fatty acids. Although the body can produce these two types from ALA, the amount it produces is not enough to meet the needs of the body. Vegetable oils, nuts and seeds contain ALA. To help you get the omega-3 daily dosage, increase your consumption of walnuts, walnut oil, flax seeds, flax seed oil, soybeans, soybean oil and canola oil.
Advantages
Meeting the daily requirement of omega-3 fatty acids not only supports the needs of the body but may also help reduce the risk for chronic diseases. A diet rich in omega-3 fatty acids can help reduce blood cholesterol levels and blood pressure, therefore reducing the risk for heart disease. Omega-3 fatty acids can also help reduce triglyceride levels, another type of fat in the body, which also helps reduce heart disease risk, especially for people with diabetes. The University of Maryland Medical Center reports that omega-3 fatty acids can help reduce inflammation, which can affect diseases like rheumatoid arthritis. Because omega-3 fatty acids are highly concentrated in the brain, increasing your intake may have an effect on conditions like depression, attention deficit hyperactivity disorder, schizophrenia and bipolar disorder; but more research needs to be conducted in these areas.
References
- Institute of Medicine; Dietary Reference Intakes -- Macronutrients; 2005
- Linus Pauling Institute; Essential Fatty Acids; Victoria Drake; April 2009
- University of Maryland Medical Center; Omega-3 Fatty Acids; Stephen Ehrlich; June 2009
- American Heart Association: Fish 101
- American Heart Association; Know Your Fats; March 2011
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