What is a fish oil supplement good for

This article was medically reviewed by Kristen Gradney, M.H.A., R.D.N., L.D.N., a registered dietitian nutritionist and member of the Prevention Medical Review Board, in August 2022.

There are so many supplements on the market that claim to be the best and provide the most important benefits. With so many super-vitamin options to choose from, finding the right ones for your regular regimen can be a journey. Fish oil benefits, however, may be worth considering for the improvement of your health, and they can be found in supplements as well as certain foods in your diet.

We spoke with Melissa Prest, C.D.N., R.D.N., National Media Spokesperson for the Academy of Nutrition and Dietetics and member of the Prevention Medical Board, to give you all the expert insight on the benefits of fish oil.

What is fish oil? What foods have fish oil in them?

Fish oil is the fat or oil that’s extracted from fish tissue. It usually comes from oily fish such as herring, tuna, anchovies, trout, salmon, and mackerel. It’s also produced from the livers of other fish, as is the case with cod liver oil.

The American Heart Association recommends eating 2 servings of fish (particularly fatty fish) per week. A serving is 3 ounces cooked, or about 3/4 cup of flaked fish. Fatty fish like anchovies, herring, mackerel, black cod, salmon, sardines, bluefin tuna, whitefish, striped bass and cobia are high in omega-3 fatty acids.

However, if you aren’t regularly eating 2 servings of these kinds of fatty fish per week, taking fish oil supplements can help you get enough omega-3s. But not all fish oils are created equal.

When you’re ready to shop for a fish oil supplement, nutritionists recommend looking for a brand that is truthful in labeling, transparent about the source of origin, and manufactured from sustainable fisheries. But before you buy, here’s everything to know.

What are the nutritional benefits of fish oil supplements?

Fish oil is rich in omega-3 fatty acids usually in the form of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), vitamin A, and vitamin D. Although studies continue to reveal more of the ways fish oil can be important for our health, here are some of the strongest claims on the good works of the super-supplement.

Supports Heart Health

According to the American Heart Association, research has shown that omega-3 fatty acids can reduce your risk of heart disease and stroke. Studies have also shown that fish oil can also provide the following benefits:

• Improved cholesterol levels. It can increase levels of HDL (good) cholesterol and may also lower levels of LDL (bad) cholesterol.
• Decreased triglycerides. It can lower triglycerides by 15–30%.
• Reduced blood pressure. Even in small doses, it helps reduce blood pressure in people with elevated levels.
• Plaque prevention. It may prevent the plaques that can cause arteries to harden, as well as make arterial plaques more stable and safer in those who already have them.

Although fish oil supplements can improve many of the risk factors for heart disease, there is no clear evidence that they can prevent heart attacks or strokes.

Supports Brain Health

Your brain is made up of nearly 60% fat, and much of this fat is omega-3 fatty acids. Therefore, omega-3s are essential for typical brain function. The omega-3 fatty acids EPA and DHA are critical for normal brain function and development throughout all stages of life.

Omega-3’s are essential for the maintenance of normal brain function throughout life. These fatty acids preserve cell membrane health and facilitate communication between brain cells.

These fatty acids have also shown to have important roles in the developing baby’s brain. Many studies have correlated pregnant women’s fish intake or fish oil use with higher scores for their children on tests of intelligence and brain function in early childhood.

Supports Eye Health

Not unlike your brain, your eyes also rely on omega-3 fatty acids. Fish oil has many advantages, both for developing vision and maintaining healthy eyes at any age.

Studies have shown that people who do not get enough omega-3s in their diet tend to be at greater risk for eye diseases, such as age-related macular degeneration.

Reduces Inflammation

Inflammation is your immune system’s way of fighting infection and treating injuries. Though, if you suffer from chronic inflammation that doesn’t resolve on its own, it can lead to more serious health issues, such as obesity, diabetes, depression, and heart disease.

Fish oil has anti-inflammatory properties, and studies have shown that it may help treat conditions involving chronic inflammation.

Reduces Liver Fat

Your liver processes most of the fat in your body and can often have an impact on weight gain.

Given the rising rates of obesity in the U.S., liver disease is also becoming increasingly common—particularly nonalcoholic fatty liver disease (NAFLD), in which fat accumulates in your liver.

Studies have shown that fish oil supplements can improve liver function and inflammation, which may help reduce symptoms of NAFLD and the amount of fat in your liver.

In addition to all these important health impacts, “some research has shown benefits to taking fish oil with pain with rheumatoid arthritis, and prevention of Alzheimer's disease and dementia,” explains Prest.

Who can benefit from taking fish oil supplements?

If getting in good sources of fish and seafood once to twice a week is difficult, fish oil supplementation may be appropriate, says Prest.

ut with any kind of supplement or medication, there are those select few who should proceed with caution.

Prest warns that “taking fish oil and an anticoagulant medication, commonly known as blood thinners, should be avoided because fish oil will decrease your ability to form a blood clot leaving you vulnerable to bleeding.” Additionally, she warns that higher doses of fish oil may elevate glucose, so talk with your provider if you have diabetes to know if it is appropriate for you to take a fish oil supplement.

Because these products are generally derived from fish products, people who have allergies to fish or fish products should also speak to their doctor prior to taking fish oil supplements.

Are there any side effects of taking fish oil supplements?

One of the biggest complaints people have with taking fish oil is fish-tasting burps, says Prest. “You can limit this by starting with a small dose and taking the fish oil with your largest meal of the day. Most side effects have been reported with higher doses so start small and increase the dose slowly.” Other side effects include nausea, diarrhea, heartburn, and abdominal pain.

Prest’s final word of warning is to check the supplement label to make sure the fish oil has been tested for heavy metals like mercury, as this can lead to further health issues.

So, if you’re interested in trying out the super-supplement for yourself, nutritionists suggest starting at a reasonable dose, 1 capsule a day with food. If you are currently on any blood thinners, are diabetic, or have a fish allergy, consult with your doctor before adding fish oil to your list of vitamins.

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.

Madeleine, Prevention’s assistant editor, has a history with health writing from her experience as an editorial assistant at WebMD, and from her personal research at university. She graduated from the University of Michigan with a degree in biopsychology, cognition, and neuroscience—and she helps strategize for success across Prevention’s social media platforms. 

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