By Nathan Blake |11/23/16
A recent survey of over 11,000 consumers revealed that fish oil is currently the second most popular nutritional supplement on the American market today, with annual spending exceeding $1.2 billion for over-the-counter fish oil pills and related supplements.
Fish oil has long been touted for its supposedly positive effects on a variety of bodily functions including lowering blood pressure, triglycerides, and cholesterol levels; preventing heart disease; inhibiting the formation of cancer cells; combatting depression and mood disorders; reversing the effects of macular degeneration; and countless others.
But what does medical science have to say about these claims? Is fish oil the cure-all it’s advertised to be, or would consumers be better off spending their money elsewhere?
Fish Oil’s (Not So) Secret Ingredient
Fish oil capsules contain concentrated amounts of omega-3 polyunsaturated fatty acids. Omega-3 fatty acids are necessary for human health, playing a crucial role in brain health and the regulation of inflammatory responses. There are three main types of omega-3 fatty acids, two of which can be found in fish oil capsules.
Eicosapentaenoic acid (EPA) is absorbed into the body by eating oily, coldwater fish like salmon, menhaden, sardines, mackerel, albacore tuna, halibut, and herring. EPA is also found in edible strains of seaweed as well as human breast milk.
Docosahexaenoic acid (DHA) is an important structural component of the human brain and is essential for its proper functioning. It also plays a primary role in maintaining the health of the eye, cerebral cortex, skin, sperm, and testicles. The human body can produce a small amount of DHA on its own, but like EPA, we get the majority of our DHA from cold-water ocean foods. DHA can also be found in organ meat, poultry, and egg yolks, though in small amounts.
The positive effects of fish oil on the human cardiovascular system have well been established, but that’s not to say no controversy exists. After evaluating the potential benefits of fish oil supplements for patients with multiple pre-existing cardiovascular disease factors, scientists concluded that DHA and EPA had neither a positive nor a negative effect on cardiovascular health. However, an early meta-analysis of fish oil studies revealed a possible correlation between fish oil supplementation and lower blood pressure. Further, scientific data indicates that fish oil consumption can reduce the risk of coronary heart disease, decrease mild hypertension, and prevent certain cardiac arrhythmias. Other studies show that fish oil capsules can be effective in the prevention of primary and secondary cardiovascular disease. In multiple clinical trials, fish oil supplements have been linked to the suppression of major coronary events. The most conclusive benefit of fish oil supplements seems to be that fish oil capsules are effective in lowering triglycerides in the blood. One study found that a prescription dose of EPA + DHA (2x the normal amount) lowered patients’ triglycerides by 27%.
Fish oil is not considered to be an effective replacement for mental health treatments, but when used in conjunction with other therapies, fish oil seems to provide beneficial effects to patients diagnosed with borderline personality disorder, unresponsive depression, and schizophrenia. EPA in particular has been studied for its possible use in regulating mood disorders, and researchers found that EPA-heavy omega-3 supplements appear to be effective against primary depression when used alongside prescription medications and other treatment. There is some evidence, however, that fish oil supplementation does not improve mood when tested against a placebo.
In a double-blind study spanning 26 weeks, researchers found that neither high nor low doses of fish oil had an observable effect on cognitive performance in patients age 65 and older. A much longer study, however, found that fish oil intake is associated with lower rates of Alzheimer’s disease. That being said, in a study of 174 Alzheimer’s patients, fish oil supplementation was not shown to reduce cognitive decline in patients with mild or moderate Alzheimer’s disease, though some positive effects were shown in a small group of patients with very mild Alzheimer’s. Other trials confirmed these finding that omega-3 supplementation is beneficial only for patients with mild cognitive impairment. While it’s still too early to make firm recommendations regarding the potential benefits of fish oil intake, daily DHA supplementation in excess of 180 mg is associated with a 50% decrease in dementia risk.
Regular consumption of EPA and DHA fatty acids significantly reduces the risk of developing age-related macular degeneration in women. Other findings suggest that increased omega-3 intake via fish oil capsules can prevent age-related macular degeneration in all subjects, sometimes by an estimated 22%. While the precise role of omega-3 fatty acids in eye health is unclear, there is some evidence that suggests DHA supplements can prevent cell damage and eye stroke injury in the retina.
A study of 250 patients with neck or back pain revealed that fish oil supplements are an equally effective but safer treatment for reducing arthritic pain compared to NSAIDs like ibuprofen and aspirin. Some studies suggest that EPA, independent from DHA, is a potential therapeutic treatment for arthritis-related inflammation in mice, and that EPA has a stronger anti-inflammatory effect than DHA. While another study’s findings suggest that fish oil supplements are not as effective in reducing chronic low-grade inflammation in obese men compared to weight reduction, multiple studies seem to suggest that omega-3 fatty acid supplements can decrease inflammation in patients, particularly those diagnosed with rheumatoid arthritis or ulcerative colitis.
Some evidence points to the benefit of fish oil’s anti-inflammatory effects on reducing the overall number of cancer cells in the colon. Another investigation found that EPA + DHA are good candidates for primary and secondary breast cancer prevention due to their abilities to reduce inflammation. Strangely enough, one recent study has shown a correlation between elevated levels of omega-3 fatty acids and an increased risk for developing aggressive prostate cancer; men with the highest DHA levels were 2.5x more likely to develop high-risk prostate cancer, though similar studies proved inconclusive. Further, other studies revealed opposite findings, that fish oils are actually helpful in reducing the risk of prostate cancer in healthy individuals, as well as preventing colorectal and breast cancer formation.
The Last Word
Ultimately, the health benefits of fish oil supplements are still unclear. Studies surrounding omega-3 supplements, as we have seen, are conflicting at best, contradictory at worst. That being said, multiple organizations agree that the potential benefits of fish oil capsules outweigh the potential risks for generally healthy people, though more evidence is needed before making a definitive claim.
Continue taking fish oil capsules if they have been prescribed to you by a physician. If you are planning to begin a fish oil regimen, consult with your primary care physician beforehand to make sure you are healthy enough and that they will benefit you. General consumers should be aware that while many of the findings referenced above are interesting, it’s entirely possible you may not be receiving the benefits you’ve been paying for.