Omega-3 polyunsaturated fatty acids also known as omega-3 PUFAs, omega-3 fatty acids and even “n-3s,”
In the 1970s, researchers from Demark discovered that although the Inuits in Greenland ate a high-fat diet (about 40% of their daily calories came from fat), they had a far lower rate of heart disease and heart attacks than people in the Western world. When the researchers investigated further they discovered that one reason was due to the Inuits’ seafood-heavy diet which was rich in polyunsaturated omega-3 fatty acids.
Several different omega-3 polyunsaturated fatty acids exist, but most of the scientific research has focused on three types: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Omega-3 fatty acids have a carbon–carbon double bond located three carbons from the methyl end of the chain. ALA contains 18 carbon atoms and is considered a “short-chain” omega-3, whereas EPA and DHA are considered “long-chain” omega-3s because EPA contains 20 carbons and DHA contains 22.
Omega-3 polyunsaturated fatty acids play an important role in the body and are involved in the structure of cell membranes. DHA, for example, is especially high in the retina, brain, and sperm. In addition, omega-3 polyunsaturated fatty acids provide energy for the body and have wide-ranging functions in the body’s cardiovascular, pulmonary, immune, and endocrine systems.
Many research studies link higher intakes of fish and other seafood with improved health outcomes. However, it is difficult to ascertain whether the benefits are due to the omega-3 content of the seafood (which varies among species), other components in the seafood, the substitution of seafood for other less healthful foods, other healthy lifestyle factors, or a combination of these factors. However, the areas of health in which omega-3 polyunsaurated fatty acids might be involved include cardiovascular disease and its risk factors. infant health and neurodevelopment, cancer prevention, Alzheimer’s disease, dementia, cognitive function, age-related macular degeneration, dry eye disease, rheumatoid arthritis, depression, inflammatory bowel disease, attention-deficit/hyperactivity disorder (ADHD), childhood allergies, and cystic fibrosis.
ALA is considered an essential fatty acid which means that it must be obtained from the diet. ALA can be converted into EPA and then to DHA, but the conversion (which occurs primarily in the liver) is very limited, with reported rates of less than 15%. Therefore, consuming EPA and DHA directly from foods and/or dietary supplements is the only practical way to increase levels of these specific fatty acids in the body.
ALA is found in plant oils including flaxseed (linseed) soyabean and canola. ALA is also found in chia seeds and walnuts.
High levels of EPA and DHA are found in cold-water fatty fish, such as salmon, mackerel, tuna, herring, and sardines, whereas fish with a lower fat content, such as bass, tilapia and cod, as well as shellfish contain lower levels. The EPA and DHA content of fish also depends on the composition of the food that the fish consumes. Farmed fish usually have higher levels of EPA and DHA than wild-caught fish, but it depends on the food they are fed.
Beef is very low in omega-3 polyunsaturted fatty acids, but beef from grass-fed cows have been found to contain somewhat higher levels of omega-3s, mainly as ALA, than that from grain-fed cows.
Some foods, such as certain brands of eggs, yogurt, juices, milk, and soy beverages, have fortified with DHA and other omega-3s.