Fish oil pills are among the most popular dietary supplements taken by Americans as nearly 8% of adults — roughly 19 million people — take them. And why? The pills contain omega-3 fatty acids — perhaps the one type of fat you don’t want to cut back on — that have been associated with a variety of health benefits, including helping with arthritis, cardiovascular disease, lower cholesterol and even depression.
But is all the hype surrounding fish oil pills backed up by scientific evidence? And are there any side effects that are concerning with the use of them? There is no doubt that omega-3s are absolutely necessary for human health, but the jury is still out on whether the supplements offer any real benefits.
Before examining the pros and cons of fish oil pills, it’s important to start with an understanding of the different kinds of omega-3s, how they work in the body and what studies have been conducted to either support or undermine the supposed health benefits of the supplement.
Why the Fish Oil Craze?
The popularity of fish oil has grown along with the large body of research linking a wide array of health benefits, especially lowering blood pressure and cholesterol, with omega-3 fatty acids. The main types of omega-3s are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are found mainly in seafood, and alpha-linolenic acid (ALA), which is found in flaxseed oil and vegetable oils. Fish oil pills often contain a combination of EPA and DHA.
“There are lots of omega-3 fatty acids in cell membranes of the brain and the nervous system in general, as well as in the heart, and they affect how different transmitters systems act,” says Jeppe Hagstrup Christensen, MD, a professor of clinical medicine at Aalborg University Hospital in Denmark who has conducted multiple studies on the topic. “Omega-3s are incorporated into these tissues when ingested, and their concentration increases. You can actually measure the increase of the fatty acids in different tissues after supplementation.”
The body requires omega-3 fatty acids for proper brain development and functions like blood clotting, digestion, fertility, and cell and muscle activity.
“Omega-3 fatty acids are essential fats — they must be consumed for normal body functions, and they are not manufactured by the body,” says Jonathan Fialkow, MD, FACC, medical director of the Chest Pain Center and Cardiac Rehabilitation Services at Miami Cardiac & Vascular Institute in Florida. They are needed in order for the body to make various substances that ease inflammation and prevent blood clotting, and there is evidence that they “protect our cells from oxidative stresses which can otherwise lead to cell damage.”
What Are Some of the Purported Benefits?
Omega-3 supplements have been associated with a range of mental and physical health benefits. In a recent study from the Journal of Nutrition, for example, a small, daily dose of fish oil led to reduction in blood pressure after 8 weeks. Some findings suggest that fish oil consumption may lower cholesterol in menopausal women and in patients with metabolic syndrome.
Numerous studies have also linked fish oil supplementation with reduced symptoms of ADHD (attention deficit hyperactivity disorder) in children, and others have found that children whose mothers consumed fish oil supplements during pregnancy had lower rates of allergic diseases such as eczema and food allergies. Other research has found a connection between omega-3 supplementation and a decrease in depression symptoms.
People suffering from depression are often deficient in omega-3 fats, which help regulate mood, explains Taz Bhatia, MD, an integrative health expert at the Atlanta Center for Holistic and Integrative Medicine.
But Does It Really Work?
While these studies point to many benefits of fish oil supplements, findings have generally been correlational, and in some cases, other research shows conflicting results. Although a number of studies have indicated that omega-3 supplementation may prevent heart disease, for instance, most have not observed this effect.
However, there is substantial evidence to suggest that supplements could help individuals who already have an elevated risk of heart disease. In a review that Fialkow published in April in the American Journal of Cardiovascular Drugs, he reports that omega-3 products have demonstrated reductions in triglycerides and total cholesterol — two factors that influence heart health — in high-risk patients.
Here’s the catch, though: Those heart-helping benefits are likely to come only from prescription versions of omega-3s, not the kind sold over the counter — and many physicians may not even know that.
Fialkow explains that different fatty acids compete with each other in cell membranes, and a diet that is rich in one particular kind of fat — like omega-6 fatty acids, which are found in foods like fats and oils, cereal products, meat and poultry — may replace the benefits of another type of fat, like omega-3s.
“Dietary supplements do not have a concentration of omega-3 sufficient to reliably raise your omega-3 level compared to other fats, which are contained in the supplements as well,” he explains.
“In addition, as a poorly regulated industry, many dietary supplement fish oils don’t contain the amount of omega-3 promoted on the label and may have impurities in their manufacturing which may inhibit the ultimate omega 3 benefit,” Fialkow added. Indeed, a 2015 analysis by scientists at Purdue University discovered that only 21 to 25% of supplements tested contained the full amount of EPA or DHA stated on the label.
What Are the Risks?
There are very few risks associated with omega-3 supplements. They can cause gastrointestinal symptoms like diarrhea or indigestion in some people, and they may be unsafe for people with seafood allergies.
Because of the anti-clotting properties of these supplements, people taking blood-thinning medications or NSAIDs (non-steroidal anti-inflammatory drugs) such as over-the-counter pain relievers should consult a healthcare provider before supplementing with omega-3 products.
While previous evidence suggested a connection between omega-3 supplementation and the risk of prostate cancer, a new review reported in Integrative Cancer Therapies concludes that such data is weak and requires further investigation.
The Bottom Line: Just Eat It
Although the downsides appear to be minimal, that may be beside the point. The bigger picture takeaway is this: Most people do not even need omega-3 supplements — they simply need to eat more foods rich in omega-3s.
“For people with healthy diets and normal metabolism, there should be no reason to take omega-3 supplements or prescriptions,” says Fialkow. Fatty fish like salmon, tuna and sardines are especially good sources of omega-3s, and the American Heart Association recommends that people eat at least 2 servings per week. Algae oil may be good source of DHA for vegetarians, and vegans can get omega-3s from nuts, chia seeds and flaxseeds or flaxseed oil.