Fish oil, the fat or oil extracted from fish tissue, typically comes from oily fish like mackerel, tuna, sardines, and herring. In some cases, fish oil comes from the livers of other types of fish, like cod liver oil.
According to the World Health Organization (WHO), adults should consume one to two servings of fish per week to enjoy the health benefits of Omega-3 fatty acids, vitamin D, and vitamin A. But if you consume less than the recommended fish intake, fish oil supplements can help you consume enough Omega-3s to enjoy their associated health benefits.
Approximately 30 percent of fish oil is composed of Omega-3s, while the remaining 70 percent contains other fats. The type of Omega-3 found in fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), provides greater health benefits than those found in plant sources (alpha-linolenic acid (ALA)). While ALA is an essential fatty acid, studies conducted by the Harvard Medical School suggest that EPHA and DHA provide a wider range of health benefits.
While the benefits of fish oil have primarily been studied in the context of heart health, other studies suggest that the consumption of fish oil can reduce inflammation, improve cognitive function, aid weight loss, and support pregnancy and early life.
According to the American Heart Association, heart disease is the leading cause of death in the United States. A recent study demonstrated that fish consumption led to reduced risks of heart disease despite high cholesterol and fat intakes.
In human health studies by the National Institute of Health, fish oil was shown to lower triglyceride levels. In patients with mild hypertension—but not in healthy people— Omega-3 fatty acids were shown to decrease blood pressure.
For individuals at high risk, fish oil can also reduce the risk of fatal ventricular arrhythmias. While fish oil supplements have been shown to promote heart health, it remains unclear whether fish oil can prevent heart attacks or strokes.
Fish oil capsules contain Omega-3 polyunsaturated fatty acids, which are associated with anti-inflammatory effects. In one study by the National Institutes of Health, Omega-3 fatty acid supplements were shown to reduce symptoms associated with inflammation in psoriasis patients, such as joint pain.
Another study demonstrated fish oil’s ability to reduce the symptoms of rheumatoid arthritis and the use of anti-inflammatory drugs in arthritis patients with severe inflammatory joint diseases such as osteoporosis and sclerosis.
The human brain is composed of approximately 60 percent fat, and the majority of this fat is Omega-3 fatty acids. As a result, consuming Omega-3 fatty acids can improve brain function and slow the progress of cognitive decline.
In clinical trials, fish oil supplements were shown to prevent and improve mental disorder symptoms. For example, fish oil capsules were shown to reduce the risk of psychotic disorders, such as schizophrenia and bipolar disorder, in individuals at high risk. In a 2008 study by Andreatini et al., fish oil and Omega-3 supplements were also shown to reduce symptoms of depression.
Additionally, in a 2012 clinical trial, Nilsson et al. demonstrated that older adults with significant fish intake tended to experience a slower age-related cognitive decline.
According to a systematic review by the New England Journal of Medicine, fish oil supplements can risk factors for heart disease and cardiovascular disease in obese individuals. Some analyses also suggest that fish oil supplements, along with diet and exercise, leads to weight loss and other beneficial effects in both obese and healthy people.
According to one study by the National Institutes of Health, Omega-3 fatty acids are essential in growth and development throughout the lifecycle. Consequently, Omega-3s are important nutrients for human health. Omega-3 and omega-6 fatty acids are important components of cell membranes and the amount of polyunsaturated fatty acids in cell membranes is primarily dependent on dietary intake.
In another study, Carlson et al. suggest that fish oil capsules and other fatty acid supplements can improve hand-eye coordination in mothers and infants. Additionally, fish oil supplements may improve early learning development and lower the risk of attention deficit hyperactivity disorder (ADHD) in younger children.
Fish oil supplements are available in numerous forms, including triglycerides (TG), phospholipids (PL), and free fatty acids (FFA). Some fish oil supplements contain up to 1,000 mg of fish oil per serving, so it’s important to keep the recommended daily dosage of Omega-3 fats in mind when purchasing supplements.
Although fish oil supplements are associated with a wide variety of health benefits, side effects may occur. While there is mixed evidence on the link between prostate cancer and fatty acid supplements, a 2013 systematic review found no correlation between fish intake and an individual’s risk for prostate cancer.
Omega-3s may increase the risk of bleeding when taken with specific medications. However, a recent systematic review of 52 studies showed that fish oil did not increase bleeding risk in healthy people.
Fish oil may also be linked to gastrointestinal side effects, including nausea, diarrhea, and vomiting. If you experience unexpected side effects, lower your daily dosage of fish oil or contact your doctor.
For individuals with shellfish or other cold-water fish allergies, fish oil can trigger an allergic reaction. Make sure to consult your doctor before adding any dietary supplements to your diet.
WHO recommends a daily intake of 0.2–0.5 grams of fish oil for adults. In other words, adults should consume 200–500 mg of combined EPA and DHA daily. If you’re at risk of heart disease or cardiovascular disease, or currently pregnant, increasing your dosage may be necessary.
If you don’t consume one to two portions of fatty fish per week, adding fish oil supplements to your diet can help you consume enough Omega-3 to enjoy its numerous health benefits.