Health Benefits of Fish Oil

It may help with a wide range of things—from fighting inflammation to protecting your heart.

A person holds a fish oil supplement capsule in one hand, a glass of water in the other.
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Fish oil is oil sourced from fatty fish like sardines, anchovies, and mackerel.¹ The oil is typically put into a supplement, either in capsule or liquid form.² Fish oil has been linked to several health benefits. For example, fish oil is rich in two omega-3 fatty acids called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have been shown to help reduce inflammation in the body.¹

Here's more about fish oil's potential health benefits and risks and why you should talk to a healthcare provider about its use.

Benefits

Fish oil is linked to a number of outcomes that affect both physical and mental health.

Helps reduce inflammation

Chronic inflammation—which is long-term inflammation that can last months to years—is associated with a risk of conditions like diabetes and heart disease.³ The EPA and DHA omega-3s in fatty fish are capable of partly blocking many aspects of inflammation.⁴ As such, increasing the consumption of EPA and DHA—such as through fish oil—is one of the dietary changes that may help reduce chronic inflammation in the body

May help slow muscle loss for older adults

The loss of muscle mass and function that comes with aging increases the risk of falls, lengthens recovery time after hospitalization, and increases death risk. Research has shown that, among men and women aged 60 to 85 years, a fish oil supplement slowed the normal age-driven decline in muscle mass and function.⁵

Possible improvements in brain function

Research in healthy adults aged 51 to 72 years found that, compared with a placebo, taking fish oil supplementation for five weeks improved brain performance, including attention and memory. Researchers also note that higher blood levels of omega-3 fatty acids have been associated with a lower risk of age-related cognitive decline.⁶

Possible improvements in mental health

Research shows that low blood levels of omega-3s are tied to an increased risk of depression and anxiety.⁷ When used with standard therapies, fish oil supplementation has been found to be beneficial in the treatment of depression as compared to a placebo.⁸

In addition, an eight-week study found that, compared to a placebo, a fish oil supplement reduced heart rate and sympathetic nervous system activity (fight or flight) in response to mental stress.⁹

May reduce blood pressure

One recent analysis of previously published studies reported that the optimal combined intake of EPA and DHA omega-3 fatty acids for reducing blood pressure is likely between two to three grams per day.¹⁰ Another found that in adults with systolic (the top number) blood pressure, daily doses of EPA and DHA as low as 0.7 grams show meaningful reductions in blood pressure, which could result in a reduced risk of heart disease.¹¹

May reduce the severity of COVID-19

A low blood level of omega-3s has been linked to an increased likelihood of developing severe COVID-19, independent of other factors. One recent study found that the consumption of fish or omega-3 supplements like fish oil may decrease the percentage of patients who develop severe COVID-19 infections.¹²

May help reduce osteoarthritis pain

Osteoarthritis (OA), a form of arthritis that wears down cartilage within joints, is a leading cause of chronic pain and disability. Worldwide, OA affects 18% of women and 9.6% of men over the age of 60. One study that involved adults with OA who were overweight or had obesity showed that fish oil supplementation lessened chronic pain and improved overall well-being.¹³

May help protect bone density

Research shows that, among older adults, the use of DHA and EPA omega-3 supplements had a positive impact on bone mineral density in the spine.¹⁴ Another study found that fish oil supplement use was associated with lower risks of bone fractures, especially among people with a higher genetic risk for this type of injury.¹⁵

May help protect eye health

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss among people over 60 in the US.¹⁶ In its later stages, the disease can lead to the loss of central vision (needed to see details straight ahead) or to blurry or wavy areas in your central vision.¹⁷

The risk of AMD increases with age, and people aged 55 years or older are more likely to develop the condition.¹⁷ But one study found that older individuals with high levels of EPA and DHA omega-3s in the outer coating of their red blood cells had a strongly reduced risk for AMD.¹⁸

May help with non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the buildup of fat in the liver for reasons other than drinking too much alcohol. Being overweight or having obesity, prediabetes, type 2 diabetes, high cholesterol, or high blood pressure increases the risk of NAFLD.¹⁹

A study in people with NAFLD found that those who took fish oil supplements had improvements in liver damage.²⁰ Another study showed that in people with both diabetes and NAFLD, omega-3 supplementation for 12 weeks improved NAFLD compared with a placebo.²¹

May help people with autism

Autism spectrum disorder (ASD) affects how people communicate, learn, and interact with others.²² One small study found that while fish oil didn't have any effects on ASD symptoms, it did improve attention and working memory in adults with the condition.²³ Another small study—this one in children with ASM—found that those who took omega-3 capsules daily for eight weeks had improvements in behaviors and social communication.²⁴

May help manage rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that involves chronic inflammation of the joints, with symptoms that include pain, swelling, and stiffness.¹ While some research is inconsistent, studies have shown that fish oil helps reduce inflammation in people with RA.¹'²⁵

Nutrition

According to the US Department of Agriculture, one teaspoon of liquid oil from sardines provides:²⁶

  • Calories: 40.6
  • Fat: 4.5g
  • Carbohydrates: 0g
  • Protein: 0g
  • Vitamin D: 0.37mcg, 2% of the daily value

However, fish oil is typically sold as a supplement, not a food. And since dietary supplements are not required to be standardized in the US, the type of fish, amount of oil (and therefore omega-3s), and capsule ingredients can vary from product to product.²⁷

Risks

According to the National Center for Complementary and Integrative Health, it's uncertain if people with fish or shellfish allergies can safely consume fish oil supplements.²

Potential side effects of taking fish oil supplements may include:¹'²

  • Minor digestive symptoms, like burping, heartburn, or diarrhea
  • An unpleasant taste in the mouth
  • Bad breath
  • Nausea
  • Headache
  • Sweat with an odor
  • Cuts that take longer to stop bleeding

People who take drugs that affect bleeding time, such as blood thinners or nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen (Advil), should discuss the use of omega-3 fatty acid supplements with a healthcare provider.²

There is conflicting research about whether fish oil could increase the risk of prostate cancer.²

Regarding heart health, one study found that, compared with a placebo, omega-3 fatty acids were associated with an increased risk of atrial fibrillation (AFib) among people with high blood triglycerides (blood fats) who have a higher risk of heart disease.²⁷ AFib is the most common type of irregular heart rhythm, which causes the heart to beat much faster than normal.²⁸

Worth noting: Fish liver oils are not the same as fish oils. Fish liver oils contain vitamins A and D, which can be toxic in high doses.²

Tips for Consuming

The Dietary Guidelines for Americans recommends that you meet your nutritional needs through what you eat. So if you eat fatty fish like salmon, mackerel, or sardines a few times a week, you may not need a fish oil supplement at all—especially if you eat the recommended eight ounces of seafood per week.

Sometimes it is not possible for someone to get the proper amount of omega-3 through food alone, though. Because it can vary so widely on how much omega-3 someone takes in through their food, there is no set government recommendation for how much fish oil you should consume in supplement form daily.¹

If you take fish oil as a supplement, follow the product's directions regarding when or how to take it.

Summary

Consider what food you can eat to get omega-3s like EPA and DHA through your diet.¹ If you don't—or can't—eat fish or need to add to your dietary intake, talk to your healthcare provider about alternate ways to consume omega-3s and whether fish oil could be an option for you.

Fish oil has several research-backed benefits, but it is a dietary supplement with potential adverse effects and interactions. Before taking fish oil, talk to your healthcare provider about the risks and benefits based on your personal medical history.² If your provider approves of taking fish oil, follow their guidance regarding the proper dosage and use, and inform them of any side effects you experience.

Sources:

  1. National Institutes of Health Office of Dietary Supplements. Omega-3 Fatty Acids.
  2. National Center for Complementary and Integrative Health. Omega-3 Supplements.
  3. National Library of Medicine. Chronic Inflammation.
  4. Calder PC. Omega-3 fatty acids and inflammatory processes: from molecules to man. Biochem Soc Trans. 2017;45(5):1105–1115. doi:10.1042/BST20160474
  5. Smith G, Julliand S, Reeds DN, Sinacore DR, Klein S, Mittendorfer B. Fish oil–derived n–3 PUFA therapy increases muscle mass and function in healthy older adults. Am J Clin Nutr. 2015;102(1):115–122. doi:10.3945/ajcn.114.105833
  6. Nilsson A, Radeborg K, Salo I, Björck I. Effects of supplementation with n-3 polyunsaturated fatty acids on cognitive performance and cardiometabolic risk markers in healthy 51 to 72 years old subjects: a randomized controlled cross-over study. Nutr J. 2012;11:99. doi:10.1186/1475-2891-11-99
  7. Liu JJ, Galfalvy HC, Cooper TB, et al. Omega-3 Polyunsaturated Fatty Acid Status in Major Depression with Comorbid Anxiety Disorders. J Clin Psychiatry. 2013;74(7):732–738. doi: 10.4088/JCP.12m07970
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  11. Minihane AM, Armah CK, Miles EA, et al. Consumption of Fish Oil Providing Amounts of Eicosapentaenoic Acid and Docosahexaenoic Acid That Can Be Obtained from the Diet Reduces Blood Pressure in Adults with Systolic Hypertension: A Retrospective Analysis. J Nutr. 2016;146(3):516-523. doi:10.3945/jn.115.220475.
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