Omega-3s are fats your body needs but cannot make on its own

Omega-3 fatty acids are a type of polyunsaturated fat found mainly in fish, seafood, and some plant sources. Your body uses them to build cell membranes, reduce inflammation, and support your heart, brain, and joints. Unlike some nutrients your body can manufacture, you have to get omega-3s from food or supplements because your body cannot produce them.

The three main types are EPA and DHA (found in fish and marine sources) and ALA (found in plants like flaxseed and walnuts). EPA and DHA are the forms your body uses most directly, which is why fish oil supplements and fatty fish are often recommended as sources.

Most people in Western diets do not eat enough omega-3s relative to omega-6 fatty acids, another type of polyunsaturated fat. This imbalance is one reason health professionals often discuss omega-3 intake—not because omega-3s are a cure, but because they play a role in how your body manages inflammation and other basic functions.

Key Takeaways

  • Omega-3 fatty acids support heart function, brain health, and joint flexibility by reducing inflammation in your body.
  • EPA and DHA, the forms found in fish and marine oils, are used more directly by your body than ALA from plant sources.
  • Your body cannot make omega-3s, so you need to consume them through food, fish oil supplements, or other sources.
  • Research shows omega-3s may help with heart health and inflammation, though results vary by individual and the amount consumed.
  • Fish oil supplements and fatty fish are common sources, but the right amount depends on your diet and health situation.

How omega-3s affect your heart and blood vessels

Omega-3 fatty acids, particularly EPA and DHA, influence how your heart beats and how your blood vessels function. They can help lower triglycerides (a type of fat in your blood), reduce blood pressure slightly, and make blood less likely to clot abnormally. These effects matter because high triglycerides and blood clots are risk factors for heart disease.

Research on fish consumption and heart health has found that people who eat fatty fish regularly tend to have better heart outcomes than those who do not. However, the benefit appears to come from eating fish as part of an overall diet, not from fish oil supplements alone. Studies on fish oil pills show mixed results—some show modest benefits for people with existing heart disease, while others show little difference.

The amount matters too. A small serving of fatty fish two or three times a week provides omega-3s in amounts that research has studied. Very high doses from supplements may have different effects than food sources and are not recommended without medical guidance.

Omega-3s and brain function, mood, and memory

Your brain is roughly 60 percent fat, and DHA is one of the main fats that make up brain cell membranes. This is why omega-3s are often discussed in relation to brain health, memory, and mood. Some research suggests that people with higher omega-3 intake perform better on memory tasks and have lower rates of depression, though the connection is not yet fully understood.

The evidence is stronger for preventing cognitive decline in older adults than for treating existing memory problems. Studies on fish consumption show that regular eaters have slower rates of mental decline, but it is unclear whether supplements produce the same effect. Most research has focused on people who eat fish regularly rather than those taking pills.

For mood, some studies show that omega-3 supplements may help reduce symptoms of depression, particularly when combined with other treatments. However, the effect is usually modest, and results vary widely between individuals. Omega-3s are not a replacement for other depression treatments, but they may be one part of an overall approach.

Joint health and inflammation

Omega-3 fatty acids reduce inflammation throughout your body by changing how your immune system responds. This is relevant to joint health because inflammatory conditions like rheumatoid arthritis involve chronic inflammation in the joints. Some people with arthritis report less joint pain and stiffness when they consume more omega-3s, and some research supports this observation.

Studies on fish oil supplements for rheumatoid arthritis show modest improvements in joint pain and swelling, particularly when people take them consistently over several months. The effect is usually smaller than prescription medications but may add to their benefit. For osteoarthritis (wear-and-tear arthritis), the evidence is weaker, though omega-3s may still help reduce overall inflammation.

General inflammation in your body—not just in joints—may also decrease with higher omega-3 intake. Chronic inflammation is linked to many age-related conditions, so reducing it is considered beneficial for long-term health, though omega-3s are one of many factors that influence inflammation.

How much omega-3 you might need

There is no single official daily requirement for omega-3s, but major health organizations offer guidance. The American Heart Association recommends eating fatty fish at least twice a week, which provides roughly 250 to 500 milligrams of EPA and DHA combined per day. This amount is based on research showing heart benefits in people who eat fish regularly.

For people who do not eat fish, supplements are an option, but the right dose depends on your age, health, and what you are trying to support. Doses studied in research typically range from 500 to 3,000 milligrams of combined EPA and DHA daily, though some studies use higher amounts. Very high doses can thin your blood and may interact with blood-thinning medications, so it is important to discuss supplements with a doctor if you take medications.

Your current diet also matters. If you already eat fish, nuts, seeds, or oils rich in omega-3s, you may be getting enough without supplements. A doctor or registered dietitian can review your diet and help you decide whether a supplement makes sense for your situation.

Fish oil supplements versus eating fish

Fish and fish oil supplements both contain EPA and DHA, but they are not identical. Eating fish provides omega-3s along with protein, vitamins, minerals, and other compounds that work together. Fish oil supplements isolate the omega-3s, which means you get a concentrated dose but miss the other nutrients.

Research on heart health has been more consistent for people who eat fish regularly than for people taking fish oil pills. This suggests that either the whole food provides benefits supplements do not, or that people who eat fish tend to have other healthy habits. For brain health and inflammation, the evidence is similar—eating fish shows benefits, while supplements show mixed results.

Fish oil supplements do have advantages: they are convenient, they do not require you to like the taste of fish, and they provide a measured dose. They are also a practical option for people with fish allergies or those who follow certain diets. The choice between food and supplements often comes down to what fits your life and what your doctor recommends based on your health.

Potential side effects and who should be cautious

Fish oil supplements are generally well tolerated, but some people experience side effects. The most common are mild: a fishy aftertaste, upset stomach, nausea, or loose stools. Taking supplements with food or choosing enteric-coated versions (designed to dissolve lower in your digestive system) can reduce these effects.

People taking blood-thinning medications like warfarin or aspirin should discuss omega-3 supplements with their doctor before starting, because high doses may increase bleeding risk. People with bleeding disorders, scheduled surgery, or fish allergies also need to check with a doctor first. Pregnant and nursing people should discuss supplements with their healthcare provider, as the right amount during pregnancy is different from other times.

Quality varies between supplement brands. Look for products that have been tested by a third party (such as NSF International or USP) to verify that the contents match the label and that the product is free of contaminants like mercury. This information is usually listed on the product website or label.

Frequently Asked Questions

Do I need omega-3 supplements if I eat fish twice a week?

Probably not. Eating fatty fish twice a week provides the amount of omega-3s that research has linked to health benefits. If you enjoy fish and eat it regularly, supplements are not necessary. If you do not eat fish or eat it rarely, a supplement or other dietary source may be worth considering, but talk to your doctor first.

Can omega-3s help with weight loss?

Omega-3s are not a weight-loss tool, though some research suggests they may support metabolism slightly. Weight loss depends mainly on overall calorie intake and physical activity. Omega-3s may help you feel full longer, which could indirectly support healthy eating, but this effect is modest and varies by person.

Is it safe to take omega-3 supplements long-term?

For most people, taking fish oil supplements at standard doses (up to 3,000 milligrams daily) long-term is considered safe. However, very high doses or long-term use should be discussed with a doctor, especially if you take medications. Regular check-ins with your healthcare provider help may support the supplement is still right for you.

What is the difference between fish oil and krill oil?

Krill oil comes from small shrimp-like creatures and contains EPA and DHA like fish oil, but in smaller amounts per dose. Krill oil also contains astaxanthin, an antioxidant. Research on krill oil is limited compared to fish oil, so its benefits are less well established. Both are options, but fish oil has more research behind it.

Can I get enough omega-3s from plant sources alone?

Plant sources like flaxseed, chia seeds, and walnuts contain ALA, a type of omega-3. Your body can convert some ALA to EPA and DHA, but the conversion is inefficient—typically only 5 to 10 percent. If you do not eat fish or marine sources, a supplement containing EPA and DHA (often derived from algae) may be more effective than relying on plant sources alone.