Possible fish oil benefits, side effects and more

Fish oil is a bit of a wellness buzzword. The supplements are often advertised as a simple way to help the heart, reduce inflammation, improve mental health and even help people live longer.

Advertising is part of why people in the U.S. spend over a billion dollars each year on over-the-counter fish oil supplements. According to the 2012 National Health Interview Survey, nearly 8 percent of adults and more than 1 percent of children take fish oil or omega-3 supplements, like docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). That’s a lot of people chasing the potential perks of these fatty acids. Many food companies are also adding fish oil to everyday products like milk, yogurt, cereal, cookies, juice and even chocolate.

So, what’s all the hype about? This article will break down the possible benefits, side effects and sources of fish oil (even if it sometimes comes with a little fishy flavor).

In this article:

What is fish oil?

Fish oil is a nutrient-rich oil extracted from the tissues of oily fish, like salmon and tuna. What makes fish oil valuable is its high concentration of omega-3 fatty acids, specifically EPA and DHA.

Interestingly, fish don’t produce these omega-3s on their own. Instead, they get them through their diet — mainly by consuming marine organisms like algae (phytoplankton), which naturally synthesize EPA and DHA.

As fish eat these organisms, they accumulate the fatty acids that people look for in fish oil.

Possible fish oil benefits

Fish oil may have a variety of possible benefits for both the body and mind.

May help lower risk of heart disease-related death

While studies show that people who regularly eat fish as part of their diet tend to have a lower risk of dying from heart disease compared to those who rarely or never eat fish, the benefits of fish oil supplements are less clear. Taking supplements may not offer the same heart-protective effects as getting omega-3s from whole food sources.

May help lower blood pressure

Eating foods or taking fish oil supplements containing EPA and DHA may help lower blood pressure in people with high blood pressure. The effect appears to be less noticeable in those with normal blood pressure. These findings can point to a potential benefit for people managing higher blood pressure levels, as determined by an individual’s health care provider.

May help lower triglyceride levels

EPA and DHA may help reduce triglyceride levels. (Triglycerides are a type of fat found in the blood.) A large 2020 review of 23 studies showed that these omega-3s may help lower triglycerides by about 15 percent when taken for over a year.

May help protect brain function

Eating more fish or taking fish oil supplements may help to support long-term brain health. A 2022 review of 33 studies found that omega-3 fatty acids from either food (like fish) or supplements could help protect against cognitive decline in healthy adults who don’t have Alzheimer’s disease or dementia.

For people already diagnosed with Alzheimer’s, the same review showed no effect on cognitive function. While omega-3s may play a role in helping to maintain brain health, they’re not a recommended treatment option for existing cognitive conditions.

May help reduce inflammation

EPA and DHA have natural anti-inflammatory properties that may help with conditions like rheumatoid arthritis (RA). Fish oil supplements containing these omega-3s may offer modest symptom relief.

Some people with RA might feel better while taking supplements that contain omega-3s. In a 2012 review, many individuals experienced shorter periods of morning stiffness, less joint tenderness and a reduced need for anti-inflammatory medications. While the effects may not be dramatic, they could help to make a meaningful difference in daily comfort and mobility.

Supports infant development

Eating fish during pregnancy and breastfeeding can be good for both the pregnant parent and their baby. It’s recommended that pregnant and breastfeeding people eat a certain amount of fish each week.

Choosing fish that are low in mercury is also recommended. Pregnant people should avoid fish that are high in mercury (including swordfish, shark, king mackerel, bigeye tuna and orange roughy). Fish should always be cooked thoroughly.

Eating fish provides nutrients that help to support a baby’s brain and nervous system development. Getting enough omega-3s during pregnancy may also help to support learning development and eye development in infants, and may also lower the risk of preterm birth and low birth weight.

What are possible sources of omega-3 fatty acids?

There’s more than one way to get some omega-3s, either through food or by taking a dietary supplement. Whether people are fans of quick-and-easy supplements or prefer something with flavor, this section gives the scoop on ways to get omega-3s.

Eating fish

Omega-3s can be found in a variety of foods, especially cold-water fatty fish, like salmon, mackerel, tuna, herring and sardines.

Choose fish that are baked or broiled rather than fried. These cooking methods help preserve the nutritional value without adding extra fat.

Fish oil supplements

Fish oil supplements are a popular way to get omega-3 fatty acids like EPA and DHA. They’re available in different forms, including capsules, soft gels and liquid oils, and some require a prescription, while others are available over the counter. Some supplements, like cod liver oil, also contain vitamins A and D, but the amounts can vary depending on the product. It's best to consult with a health care provider before starting a supplement.

While supplements can be helpful, eating fish may offer stronger benefits than taking fish oil in capsule form for specific health conditions. Whole food sources provide a range of nutrients that work together to help support overall health.

Possible fish oil side effects

Fish oil supplements are generally well tolerated, and most side effects are mild. Still, some people may experience:

• Bad breath
• Diarrhea
• Headaches
• Heartburn
• Nausea
• Strong-smelling sweat
• Unpleasant taste

In rare cases, taking too much fish oil could possibly raise the risk of stroke. That’s why it’s important to check with a health care provider before starting a supplement.

Key takeaways

Fish oil is packed with omega-3s like EPA and DHA, which are nutrients that may help support heart health, reduce inflammation and support a baby’s development during pregnancy. While eating fish regularly may offer more consistent benefits, supplements can still play a helpful role.

Many people tolerate fish oil well, but mild side effects like a fishy aftertaste or upset stomach can occur. If people take too much fish oil, it could potentially increase their risk of a stroke. It’s always recommended that people check in with a health care provider before starting a fish oil supplement.