Even though omega-3s — essential fatty acids that play a vital role in cell membrane health, as well as brain function and inflammation — are naturally found in an array of whole foods, many Americans prefer to take a fish oil supplement to make sure they're getting enough.
In fact, according to the National Health Interview Survey, nearly 19 million adults in the United States took omega-3 capsules in 2012, making it the most popular natural product used by adults that year.
And while this supplement is available in a variety of forms (like fish oil, krill oil and cod liver oil), it's important to understand the potential pros and cons of adding this over-the-counter pill to your daily regimen.
What Are Fish Oil Supplements?
Fish oil is extracted from cold-water fish such as salmon, mackerel, herring and cod.
It contains a blend of omega-3 fatty acids made up of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both of which are essential for such basic bodily functions as muscle activity and cell growth.
Our bodies can't make these omega-3 fats, so we have to take them in through foods or supplements. Good dietary sources include the fish mentioned above, as well as shellfish — such as crabs, mussels and oysters — and some nuts and seeds, like chia and flax seeds, according to MyFoodData.com, which is powered by the U.S. Department of Agriculture.
A recommended dosage for omega-3s hasn't been established, according to the National Institutes of Health (NIH). However, a lack of these healthy fats has been associated with numerous chronic conditions, including cardiovascular disease, mood disorders and certain cancers, according to Harvard Health Publishing.
For this reason, many people turn to fish oil supplements to make sure they're getting enough. While these are deemed "generally safe," per the Mayo Clinic, it's a good idea to get to know the science-backed benefits as well as three potential risks if you're planning to add these nutrients to your dietary plan.
4 Potential Benefits of Taking Fish Oil
1. Improved Heart Health
Taking a fish oil supplement may help keep your ticker in tip-top shape, according to a body of research.
A study published August 2016 in the American Heart Association (AHA)-powered journal Circulation analyzed the effect that a daily dose of fish oil had on heart attack survivors over a six-month period. Researchers found that this treatment improved the function of the heart, reduced scarring in the undamaged tissue within the heart muscle and decreased biomarkers for inflammation.
Also, according to an April 2017 study from the same organization, adults with coronary heart disease who were prescribed a low-dose omega-3 fish oil supplement were 9 percent less likely to be hospitalized or die from the condition.
What's more, a meta‐analysis of 13 randomized controlled trials found that supplementing with seafood-based omega-3s (such as fish oil) is linked to a lower risk of getting a heart attack or developing heart disease, per a September 2019 study in the Journal of the American Heart Association (JAHA).
Supplementing with marine-based omega-3s (or eating more fatty fish such as salmon) was linked to lower triglycerides and larger HDL particles, which are better at removing unhealthy cholesterol and potentially preventing plaque buildup and heart disease, in a February 2020 JAHA study that included over 26,000 women.
2. Decreased Cholesterol Levels
Whether you get it from your diet or a supplement, omega-3 fatty acids may help move the meter when it comes to your total cholesterol.
In a December 2017 study published in the journal Nutrition & Diabetes, study authors examined the lipid profiles (blood tests that show cholesterol and triglyceride levels) of patients with hyperlipidemia — another name for high cholesterol — who either took a fish oil supplement or consumed fish twice a week for eight weeks.
The result? All of the volunteers' total cholesterol and triglyceride levels were "reduced significantly" at the end of the period.
3. Better Brain Function
The healthy fats in fish oil may also benefit your mind, especially as you age.
Researchers from the Warren Alpert Medical School of Brown University studied several hundred older adults over a period of several years, and had them complete neuropsychological tests and brain scans every six months.
Those who started the study with regular cognitive function and took a regular fish oil supplement showed lower rates of cognitive decline, according to the study results, published in the February 2015 issue of Alzheimer's & Dementia.
However, it's important to note that the participants who began the study with a diagnosis of either mild cognitive impairment or Alzheimer's disease did not show improvement.
4. An Effect on Aging
Taking a fish oil supplement may also have benefits beyond the brain as we get older.
In an August 2012 study published in Brain, Behavior, and Immunity, 138 overweight but healthy middle-aged and older adults were given either a fish oil supplement or a placebo over the course of four months.
Researchers found that those who consumed the supplement experienced an increase in the length of telomeres, a DNA sequence found in chromosomes that shortens as a result of aging.
Plus, since those in the supplement group also showed a reduction in inflammation, study authors believe both of these benefits could lessen the risk of chronic conditions that are typically associated with aging, such as arthritis and Alzheimer's disease.
3 Possible Risks Linked to Fish Oil
1. Increased Prostate Cancer Risk
The verdict is still out, but it seems the fatty acids in fish oil may affect a man's risk for prostate cancer.
A July 2013 study published in JNCI: Journal of the National Cancer Institute found that men with high blood concentrations of omega-3PUFA (polyunsaturated fatty acids) have an increased likelihood of developing the disease.
But some similar research, including a March 2017 review of 44 studies in Integrative Cancer Therapies, has found a possible link between higher levels of omega-3 fatty acid intake and lower mortality rates from prostate cancer. In short: Further research is necessary to draw any firm conclusions.
2. Gastrointestinal Issues
The Mayo Clinic warns that these supplements could cause problems with the digestive system, including indigestion, nausea and loose stools, especially in people who already have gastrointestinal issues.
In fact, a February 2014 study in the Cochrane Database of Systematic Reviews discovered that fish oil pills may lead to upper gastrointestinal tract symptoms, such as an upset stomach, in patients who are managing Crohn's disease.
3. Harmful Interactions
Taking an omega-3 fatty acid supplement could result in bleeding problems if mixed with blood-thinning medication, states the NIH.
These supplements have also been shown to decrease vitamin E levels in the body, and, if taken with prescription blood pressure medicine, fish oil could cause blood pressure to rise, according to the Mayo Clinic.
- NCCIH: "Use of Complementary Health Approaches in the U.S."
- Harvard Medical School: "Fish oil: Friend or foe?"
- AHA: "Effect of Omega-3 Acid Ethyl Esters..."
- AHA Circulation: "Omega-3 Polyunsaturated Fatty Acid (Fish Oil) Supplementation..."
- Nutrition & Diabetes: "Comparison of the effect of omega-3 supplements and fresh fish on lipid profile"
- Lab Tests Online.org: "Lipid panel"
- AHA: "Prevention and Treatment of High Cholesterol (Hyperlipidemia)"
- Alzheimer's & Dementia: "Association of fish oil supplement use..."
- ScienceDirect.com: "Omega-3 supplementaion lowers inflammation in healthy middle-aged and older adults"
- Journal of the National Cancer Institute: "Plasma Phospholipid Fatty Acids and Prostate Cancer Risk"
- Integrative Cancer Therapies: "Fish-Derived-Omega-3 Fatty Acids and Prostate Cancer"
- Mayo Clinic: "Fish oil"
- NCBI: "Omega-3 fatty acids (fish oil) for maintenance of remission in Crohn's disease"
- NIH: "Omega-3 Fatty Acids"
- MyFoodData.com: "Top 10 Foods Highest in Omega 3 Fatty Acids"
- JAHA: "Marine Omega‐3 Supplementation and Cardiovascular Disease: An Updated Meta‐Analysis of 13 Randomized Controlled Trials Involving 127,477 Participants"
- JAHA: "Marine Omega‐3 Supplementation and Cardiovascular Disease: An Updated Meta‐Analysis of 13 Randomized Controlled Trials Involving 127 477 Participants"