Most foods contain a combination of different types of fat. Saturated fat and trans fat are the potentially harmful dietary fats. Polyunsaturated fats, or PUFAs, provide health benefits; however, like all other fats, they are high in calories and need to be consumed in moderation. There are two types of polyunsaturated fats: omega-3 fatty acids and omega-6 fatty acids. The major sources of polyunsaturated fat include oils, fish and nuts.
Health Benefits of Polyunsaturated Fats
Polyunsaturated fats are those that have more than one double-bonded, or unsaturated, carbon in the molecule. They are needed to build the membranes of your body's cells and the protective covering for your nerves. The American Heart Association states that polyunsaturated fats help your body rid itself of newly formed cholesterol and reduce the fatty deposits in your artery walls. They can also help lower your triglyceride level, as well as help reduce your "bad" LDL cholesterol level, improving your total cholesterol profile. Additionally, polyunsaturated fats have heart-health properties. For example, they act as anti-inflammatory and anti-blood clotting agents. They have also proven effective in lowering blood pressure, according to the University of Maryland Medical Center. In addition, they can help reduce your risk and symptoms of several diseases including rheumatoid arthritis, diabetes, stroke, coronary artery disease, irregular heartbeat, inflammatory bowel disease, lupus, eczema, some cancers and mental decline.
Oils
Polyunsaturated fats are typically liquids and generally won't become solid when cooled like a saturated fat. Common oils that contain high amounts of PUFAs include corn, cottonseed, safflower, soybean, sunflower and sesame oils. Some of the oils are omega-6 fatty acids. They contain linolenic acid, while some are omega-3 fatty acids, containing alpha-linolenic acid. Both fatty acids are called essential because your body needs them for important functions, but it can't make them on its own. The only way you can get them is through your diet.
Fish
Fatty fish are also an excellent source of the omega-3 type polyunsaturated fat. You'll find this nutrient in salmon, mackerel, herring, trout, tuna and sardines. The forms of polyunsaturated fat these fish contain include eicosapentaenoic acid, or EPA, and docosahexaenoic acid, DHA, which are sometimes referred to as marine omega-3s.
Nuts and Seeds
Walnuts, flaxseed, and pumpkin and sunflower seeds are great sources of PUFAs. So are butternuts, pine nuts, watermelon seeds, sesame seeds, chia seeds and pecans. These sources generally provide omega-3 fatty acids.
Other Sources
You will also find polyunsaturated fat in unusual places like soft margarine, mayonnaise, some salad dressings, algae and krill. Dark, leafy vegetables also contain small amounts of polyunsaturated fats.
Needs
The 2010 Dietary Guidelines for Americans recommends that you keep your intake of all fats low, consume PUFAs over saturated fats and get no more than 10 percent of your total fat from saturated sources. The American Heart Association states that no more than 25 to 35 percent of your daily calories should come from fat and that you'll get more health benefits if you consume polyunsaturated fat while dramatically reducing your intake of saturated fat. Taken together, you should aim for 15 to 25 percent of your daily calories to come from PUFAs.
References
- American Heart Association: Polyunsaturated Fats
- Medline Plus: Fat
- MayoClinic.com: Dietary Fats: Know Which Types to Choose
- University of Maryland Medical Center: Fat-Overview
- Harvard Medical School: The Truth about Fats: Bad and Good
- Harvard School of Public Health: Omega-3 Fatty Acids: An Essential Contribution
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