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Fish is a staple in many health-conscious diets thanks to its nutrient-dense profile. Many types of fish are rich in omega-3 fatty acids, which may support heart health, in addition to offering other benefits, according to research. The American Heart Association recommends eating two servings of fatty fish like salmon or sardines per week.
Individuals who don’t consume enough omega-3 fatty acids from food sources in their regular diet may benefit from fish oil supplements. Read on to learn more about fish oil and omega-3 fatty acids, potential health benefits and side effects, as well as expert insights into how to choose the best fish oil supplement for you.
- Rich in the long-chain omega-3 fatty acids EPA and DHA
- Easily recognized by the body and gentler on the stomach
- Enhance glucose metabolism in your liver
- Decrease cholesterol synthesis
- Gluten-free and non-GMO
What Are Fish Oil Supplements?
Fish oil supplements typically come in gel capsules or liquid form and contain oil from fatty fish, which is rich in omega-3 fatty acids. Common sources of fish oil include anchovies, mackerel, herring, sardines, salmon, cod and bluefin tuna.
Fish oil supplements contain two of the three most important omega-3 fatty acids: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are typically found in fish and other types of seafood. The third omega-3 fatty acid is alpha-linolenic acid (ALA), which can be found primarily in plant oils like flaxseed and canola oils. While the human body can convert some ALA into EPA and then into DHA, that generally only produces small amounts—so eating fish and other marine sources, or using dietary supplements, can help increase levels of these fatty acids in the body.
“If you’re regularly eating fatty fish like salmon, sardines or mackerel a couple of times a week, you might not need a fish oil supplement,” explains Jaclyn London, a New York-based registered dietitian. “But for the rest of us? It can help fill in the gaps.”
Potential Health Benefits of Fish Oil
The two omega-3 fatty acids found in fish oil supplements, EPA and DHA, are directly involved in building cell membranes and regulating inflammatory processes in the body, and they also play a critical role in supporting heart, brain and eye health, according to London. “These fats have been shown to help reduce triglycerides (a type of fat in the blood), support healthy blood pressure and may help tamp down chronic low-grade inflammation. Some research also suggests benefits for mood, cognitive function and even joint health,” she adds.
Further clinical investigation is needed to verify certain health claims associated with taking fish oil supplements and omega-3 fatty acids, such as reducing the risk of certain cancers, improving dry eye disease, alleviating symptoms of rheumatoid arthritis and improving mood. However, some research indicates supplements containing omega-3 fatty acids may improve health in specific use cases, as noted below.
May Improve Heart Health
“The strongest evidence for omega-3 [fatty acids] is associated with their cardiovascular benefits,” explains Avery Zenker, a registered dietitian based in Ontario, Canada. Omega-3 fatty acids play an important role in heart health and are linked to reduced inflammation and lower blood pressure and triglycerides, which reduces the risk for heart disease, according to the American Heart Association[1].
Of note, a 2019 meta-analysis of 13 clinical studies in the Journal of the American Heart Association showed that people who used marine omega-3 supplementation (fish oil or oil from marine sources like krill) had an 8% lower risk of heart attack, an 8% lower risk of dying from heart disease and a 7% lower risk of dying from cardiovascular disease[2].
Can Potentially Lower Triglyceride Levels
High levels of triglycerides, the most common type of fat in the body, combined with elevated levels of low-density lipoprotein (LDL) cholesterol or low levels of high-density lipoprotein (HDL) cholesterol, is linked with plaque buildup within the artery walls, which can increase the risk of heart attack and stroke. Omega-3 fatty acids are thought to help lower triglycerides by reducing the amount of a triglyceride-transporting lipoprotein produced in the liver.
A 2023 meta-analysis, also in the Journal of the American Heart Association, examined 90 different studies and found that omega-3 supplementation can lower blood fats like triglycerides, especially in individuals with high cholesterol or overweight[3].
May Reduce Inflammation
Inflammation is your body’s way of helping injured tissue heal, and, when the wound heals, inflammation goes away. Chronic inflammation, however, is an inflammatory process that occurs even if there isn’t an injury—and it often continues without clear reason why. It can be caused by persistent infections, abnormal immune reactions or even obesity.
A 2022 umbrella meta-analysis, which included 32 different meta-analyses, found that omega-3 supplementation significantly lowered levels of C-reactive protein (CRP) and other markers of inflammation[4].
Can Support Prenatal and Infant Health and Development
Omega-3s are often recommended during pregnancy and are commonly found in prenatal vitamins.
A 2023 meta-analysis in Archives of Gynecology and Obstetrics showed that omega-3 intake during pregnancy was linked to reduced risk of preeclampsia (high blood pressure that develops after 20 weeks’ gestation), longer gestation, lower rates of preterm birth and increased birth weight[5]. Of note, the form of omega-3 intake (food or supplement) wasn’t specified, and there was some variability between trials, so further studies are needed.
A 2024 meta-analysis involving 16 studies also found that consuming omega-3 supplements significantly reduces the risk of developing preeclampsia, further supporting this potential benefit[6].
Additionally, a 2022 review of meta-analyses of randomized trials concluded that omega-3 supplementation during pregnancy may protect against preeclampsia, low birth weight, preterm delivery and postpartum depression, and can improve the immune system and visual activity in infants[7].
May Enhance Cognitive Function
Some studies show that people who consume higher amounts of omega-3s from food like fish may have a lower risk of developing Alzheimer’s disease, dementia and other cognitive function impairments.
A 2024 meta-analysis examining omega-3 fatty acid supplementation also showed some improvement in executive functioning among middle-aged and older adults[8]. However, while initial research is promising, inconsistent results among studies indicate the need for further scientific investigation into the effects of omega-3 fatty acids on cognitive health.
Individuals who want to add a fish oil supplement to their wellness regimen should follow the manufacturer’s instructions and speak with a health care practitioner for specific dosing needs and queries.
Potential Side Effects of Fish Oil Supplements
According to the National Institutes of Health, side effects associated with taking omega-3 supplements, including fish oil supplements, are typically mild and may include:
- An unpleasant taste in the mouth
- Bad breath
- Heartburn
- Nausea
- Stomach discomfort
- Diarrhea
- Headache
- Potent body odor
Additionally, according to London, individuals who are allergic to fish or shellfish should avoid fish oil supplements unless the supplements have been tested and confirmed safe for consumption.
Fish oil supplements can also have a mild blood-thinning effect, says London, so people who have a bleeding disorder, such as hemophilia, or are taking blood-thinning medications should consult with a health care professional before taking fish oil supplements.
Types of Fish Oil Supplements
Fish oil supplements contain EPA and DHA omega-3 fatty acids, as well as ALA, the form of omega-3 found in plants. Each type has different chemical and absorption properties. In addition to general fish oil supplements, fish-derived omega 3 supplements may include:
- Fish liver oil (like cod liver oil) contains EPA and DHA, as well as vitamins A and D, in amounts that vary from product to product.
- Krill oil, which is made from krill, shrimp-like crustaceans and a favorite food of blue whales. Krill oil contains omega-3 fatty acids, antioxidants and nutrients.
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How To Choose the Best Fish Oil Supplement
Choosing a fish oil supplement among myriad options can be challenging, but keeping a few key quality markers in mind can help. According to Zenker, these may include:
- Third-party laboratory testing to ensure purity, potency and absence of contaminants like mercury or polychlorinated biphenyls (PCBs), chemicals that were used in hundreds of industrial and commercial applications (like hydraulic equipment, plastics and rubber products, and pigments and dyes) until they were banned in 1979 because of their toxicity—but may still be found in products and materials produced before the ban
- Comprehensive ingredient lists, including the source of the fish oil and specific amounts of EPA and DHA
- Quality and sustainability certifications, like the Marine Stewardship Council (MSC) seal that can indicate environmentally responsible harvesting of seafood
- Additional health-promoting ingredients, such as antioxidants like vitamin E (which may be called tocopherols in the ingredients)
- Being within the expiration date and not rancid
Additionally, Zenker says, the fishy taste of these supplements can be off-putting for some people. Choosing one with added flavor (like lemon) can potentially increase the likelihood of taking it more regularly.
How Much Fish Oil Do I Need?
According to London, there’s no official recommended daily value for omega-3 fatty acids.
When it comes to meeting your nutritional needs, says London, supplements are only meant to fill in the gaps from what might be missing in your diet. A high-quality fish oil supplement can be a helpful insurance policy, explains London, but it’s not a substitute for a healthy diet.
