Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid, precursors of certain eicosanoids that are known to reduce inflammation in the body and improve hypertriglyceridemia.
Per cent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.
Fish oil is loaded with omega-3 fatty acids. These must come from food, since our bodies can’t make them.
The two key omega-3 fatty acids are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Fatty fish like salmon, mackerel, and sardines are rich in these omega-3s. Some plants are rich in another type of omega-3 fatty acid, alpha-linolenic acid, which the body can convert to DHA and EPA. Good sources of these are flaxseeds, chia seeds, walnuts, pumpkin seeds, and canola oil.
Omega-3 fatty acids play important roles in brain function, normal growth and development, and inflammation. Deficiencies have been linked to a variety of health problems, including cardiovascular disease, some cancers, mood disorders, arthritis, and more. But that doesn’t mean taking high doses translates to better health and disease prevention.
Fish oil supplements have been promoted as easy way to protect the heart, ease inflammation, improve mental health, and lengthen life. Such claims are one reason why Americans spend more than $1 billion a year on over-the-counter fish oil. And food companies are adding it to milk, yogurt, cereal, chocolate, cookies, juice, and hundreds of other foods.
But the evidence for improving heart health is mixed. In November 2018, a study reported in the New England Journal of Medicine found that omega-3 fatty acid supplements did nothing to reduce heart attacks, strokes, or deaths from heart disease in middle-age men and women without any known risk factors for heart disease. Earlier research reported in the same journal in 2013 also reported no benefit in people with risk factors for heart disease.
However, when researchers looked at subgroups of people who don’t eat any fish, the results suggested they may reduce their cardiovascular risk by taking a fish oil supplement.
Evidence linking fish oil and cancer has been all over the map. Most research, including the 2018 study cited above, has not shown any decreased risk of cancer. However, some earlier research suggested diets high in fatty fish or fish oil supplements might reduce the risk of certain cancers.