5 Pros of Fish Oil Supplements — and 5 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.

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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, sardine oil and cod liver oil.


What Are Fish Oil Supplements?

Fish oil is extracted from cold-water fish, including salmon, mackerel, sardines, 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.


The supplements will differ in ingredients — some will focus on sardine oil, for example, while another may be more concentrated in salmon or anchovy oil.

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 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 benefits, 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. May Improve 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.

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.

Fish Oil and Arrhythmia

While studies have found fish oil omega‐3 supplements to lower risk for heart attack and death from coronary heart disease, some research raises concerns over fish oil's connection to atrial fibrillation (a-fib),

With this condition, also known as heart arrhythmia, the heart's upper chambers quiver chaotically instead of contracting effectively.

In an April 2021 analysis of five past clinical trials in the ‌European Heart Journal, ‌researchers found that trial patients given prescription omega-3s were over one-third more likely to develop atrial fibrillation than those given a placebo.

Omega-3 patients were 37% more likely to develop a-fib compared to placebo patients. In the studies, the fish oil doses taken ranged from 0.84 grams to 4 grams per day.

While a-fib is not immediately life-threatening, it may lead to complications like heart failure or stroke.

It's important to note that the study examined the effects of prescribed fish oil, not the supplements available over the counter. Still, the American Heart Association recommends eating two servings of fish a week to garner the benefits of fish oil.

More research is needed to fully understand the connection between prescription fish oil and a-fib.

2. May Help 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? Both groups of participants had significantly reduced total cholesterol and triglyceride levels at the end of the eight-week period.

3. May Boost 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. May Have a Positive Effect on Aging

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


In an older 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.

Similarly, because of fish oil's anti-inflammatory content, taking the supplement may help reduce pain associated with conditions like tendonitis and joint pain, according to the University of Pittsburgh Medical Center.

While more research is needed to understand the impact omega-3s have on physical aches and pains, one October 2018 study in BMJ Open Sport & Exercise Medicine found that these supplements may have a modest effect on disability and pain outcomes in people diagnosed with rotator cuff related shoulder pain.

5. May Help Improve Sleep

More research is needed, 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 an older animal study 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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Other Possible Benefits of Fish Oil Supplements

Fish oil has been credited for all types of healing — some claims have more substantial support because more research has been performed on the topic.

The following potential benefits may not have as much evidence as those listed above, but may be helpful in better understanding different fish oil uses.

1. May Boost Skin Health and Appearance

While more research is needed to fully grasp fish oil's effect on skin health, some studies show promise.

The fatty acids in fish oil may be helpful in improving skin barrier function, inhibit UV-induced inflammation and hyperpigmentation, reduce dry skin, accelerate skin wound healing and prevent skin cancer development, per an August 2018 review in ‌Marine Drugs.

Fish oil may also play a role in reducing the appearance of fine lines. In an August 2013 study in the International Journal of Cosmetic Science, post-menopausal people who were given a supplemented drink containing soy isoflavones, lycopene, vitamin C and vitamin E along with a fish oil capsule saw a clinically measurable improvement in the depth of facial wrinkles following long-term use.

Collagen, a structural protein found in the body's tissues, helps support cell health and maintain tissue structure, according to the Cleveland Clinic. The protein is important for healthy looking skin, and research suggests that a fish oil supplement may support collagen growth and reduce the appearance of facial wrinkles.

Your body starts to make less collagen as you age — this tends to start in your mid-20s — so many people also rely on collagen supplements to enhance their skin's appearance.

Among the many different types of collagen supplement offerings is marine collagen, which is collagen sourced from fish. More research is needed to understand the different effects of fish collagen.

2. May Support Thyroid Health

Some studies have looked at the effects of fish oil for thyroid health, or for helping to treat hypothyroidism.

Omega-3 fatty acids are believed to be especially beneficial for people with autoimmune thyroid diseases, because they boast both anti-inflammatory and immune modulating properties, according to older January 2012 research in ‌Contemporary Clinical Trials‌.

Even so, more research is needed. If you have a problem with your thyroid and want to supplement with omega-3s or fish oil, speak with a health care professional.

3. May Provide Sinus Pain Relief

Sinusitis is the inflammation of the air-filled cavities of the skull that occurs due to bacterial, viral and fungal infections of the cavities.

An older April 2012 study in the World Allergy Organization Journal suggests that cod liver oil, which is high in vitamins A and D — both of which have natural anti-inflammatory properties — may help to reduce inflammation of the mucus membranes.

Additionally, the study suggests that fish oil may help to decrease the dryness of the lining of the respiratory tract and retain moisture in the the nasal passages.

More research is needed to understand how cod liver oil can be beneficial for sinus infections.

5 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. Possibly Linked to Increase 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) may 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. Sometimes Associated With 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.

Fish oil capsules can leave behind a fishy aftertaste in some people, and others are bothered by fishy-tasting burps.

Enteric coatings are sometimes used on fish oil supplements to hamper that fishy aftertaste, They do this by keeping the capsule from dissolving until it reaches the small intestine.

Enteric-coated fish oil is considered safe and, per older April 2011 research in the Journal of Functional Foods that involved 12 participants, is not believed to have an effect on the efficacy of the capsule's ingredients.

3. May Cause 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.

Anti-platelet drugs like Plavix (clopidogrel) or anticoagulants like Coumadin (warfarin) with high dose omega-3 supplements can increase the risk of bleeding or easy bruising. While these correlations are not terribly common, if you're on this type of medicine, it's wise to talk to your doctor before taking and omega-3 supplement like fish oil, according to the Mayo Clinic.

Since fish oil is a natural blood thinner, it reduces your blood's ability to clot, and therefore, bleeding caused from capillary damage may take longer than normal to stop. As a result, when veins and capillaries break, it's possible for blood to leak out of the vessels, pool under the skin and create a bruise.

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 drop, per the Mayo Clinic.

4. May Worsen Insomnia Symptoms

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.

5. Missing Nutrients

While fish oil supplements may help provide benefits of the fish oil you get by eating fish, it won't provide the other healthful aspects of fish.

When you score your omega-3's from food sources, you'll also be eating other nutrients contained in that food. Sardines are an excellent source of DHA and vitamin B12, for example, while fish oil tablets or capsules may provide DHA, but won't offer B12.

The American Heart Association advises eating two servings of fish per week to reap the benefits of omega-3s and beyond. If fish is accessible to you and you enjoy eating it, the whole food source might be a better option.

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.

Coenzyme Q10, or simply Q10, may also offer skin benefits. Coenzyme Q10 may help diminish fine wrinkles around the eyes, according to the Mayo Clinic, and may also protect against sun damage. This may be why some people take Q10 for their skin, especially the skin on their face.