5 Pros of Fish Oil Supplements — and 4 Cons to Know

Weigh the pros and cons of fish oil supplements before you add them to your daily regimen.
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Omega-3 fatty acids are an important part of a healthy diet: they play a vital role in ensuring the health of your cells and brain, and they can help keep inflammation in check.

While these essential fatty acids can be found in an array of whole foods, including fish, nuts, seeds, avocados and plant oils, per the National Institutes of Health (NIH), many Americans prefer to take a fish oil supplement to ensure they're getting enough.

In fact, at least 10 percent of people in the United States take a fish oil supplement, according to AARP, making it one of the most popular supplements on the market. Omega-3 supplements are available in several forms, including fish oil, krill oil and cod liver oil.

What Are Fish Oil Supplements?

Fish oil is extracted from cold-water fish, including salmon, mackerel, herring and cod, per the Mayo Clinic. The substance 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.

Because our bodies don't make these omega-3 fats, we have to source them through food 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 the USDA. The supplements are available in liquid, capsule and pill form, per the Mayo Clinic.

While there's no exact recommended dosage for omega-3s, per the National Institutes of Health (NIH), we do know that an absence of this essential nutrient is associated with a number of 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 fish oil pros and cons if you're planning to add these nutrients to your dietary plan.

Most fish oil capsules contain between 600 milligrams and 1 gram of fish oil. Always follow the manufacturer's instructions on the package or talk with a health care professional to determine your correct dose. A general recommendation is 1 gram per day, according to Harvard Health Publishing.

5 Pros of Fish Oil Supplements

Here are the possible benefits of these omega-3 supplements, according to research.

1. Improved Heart Health

Taking a fish oil supplement may help keep your ticker in tip-top shape, according to a body of research.

An August 2016 study in ​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.

Additionally, according to an April 2017 study in the same journal, 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 having 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 more than 26,000 people who identified as female.

2. Lower 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 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 participants' 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​.

It's important to note, however, that the participants who began the study with a diagnosis of either mild cognitive impairment or Alzheimer's disease did not show improvement.

A July 2020 study in ​Neurology​ found that omega-3s are linked to significantly greater volumes of white matter and hippocampus and that omega-3s were tied to attenuating the effects of pollution on the brain in women ages 65 to 80 without dementia.

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4. A Positive Effect on Aging

Taking a fish oil supplement may also have benefits beyond the brain as we get older.

In an August 2012 study 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 shorten as a result of aging.

Plus, because those in the supplement group also showed a reduction in inflammation, study authors believe both of these benefits could lower the risk of chronic conditions that are typically associated with aging, such as arthritis and Alzheimer's disease.

5. Improved Sleep

More research needs to be done, but some evidence shows that fish oil can help you sleep.

Fish oil plays a role in enhancing the secretion of melatonin, a hormone that helps to regulate sleep and wake cycles, according to older studies analyzed in a September 2008 edition of ​Nutrition​.

Similarly, an August 2014 study in the ​Journal of Sleep Research​ found that taking 600 milligrams of omega-3 fatty acids daily for 16 weeks helped improve sleep quality in children.

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4 Cons of Fish Oil Supplements

It's not all perfect when it comes to fish oil. There are some risks associated with taking the supplement.

1. Increased Prostate Cancer Risk

The verdict is still out, but it seems possible that the fatty acids in fish oil may affect the risk of prostate cancer.

A July 2013 study in the 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.

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2. Gastrointestinal Issues

Taking fish oil supplements could cause problems within the digestive system, including indigestion, nausea and loose stools, especially in people who already have gastrointestinal issues, per the Mayo Clinic.

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. Bleeding and Blood Pressure Problems

Taking an omega-3 fatty acid supplement could result in bleeding problems if mixed with blood-thinning medication, according to 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.

4. Insomnia

Yes, better sleep is listed as one of the pros of fish oil, but some research suggests too much of the stuff could interfere with sleep.

A March 2015 study in ​Oxford Medical Case Reports​ reveals that, for one patient with a history of depression, taking a high dose of fish oil worsened symptoms of insomnia and anxiety. Still, more research is needed to determine fish oil's general effect on sleep.

What About CoQ10 and Fish Oil?

Fish oil and coenzyme Q10 both may benefit people with heart conditions.

CoQ10 is an antioxidant produced naturally in the body, per the Mayo Clinic. It's also found in some foods, including meats, fish and nuts, but the amount in these foods isn't enough to boost your body's levels of CoQ10, which is why some people choose to take it as a supplement.

CoQ10 has been shown to improve symptoms of congestive heart failure and it may help reduce blood pressure. It may also help people recover from bypass and heart valve surgeries.