People with more of the good omega-3 fats (EPA and DHA) in their red blood cells tend to have less heart disease and do better over time if they already have heart problems.

Taking fish oil supplements with EPA and DHA might help keep your blood from clotting too easily, which could lower your chance of having a heart attack or stroke if you already have heart disease.

EPA and DHA are two types of omega-3 fats that work differently in your body—one might calm inflammation, the other might change how your body stores fat—and that’s why some studies show benefits when you take them together, but others don’t, depending on which one you use alone.

Omega-3 fats from fish, called EPA and DHA, may help calm down harmful inflammation in your heart and blood vessels by blocking some of the body’s alarm signals, which could lower your risk of heart disease and heart failure.

Taking a lot of DHA (a type of omega-3 from fish oil) every day can drop your bad blood fats by about a quarter to a third—if you already have high levels—but EPA (another omega-3) doesn’t work as well, so DHA is the better choice for lowering triglycerides.

If you're a healthy young adult, taking a high-purity fish oil supplement might help your body absorb more of the good omega-3s (like EPA and DHA) into your red blood cells compared to a lower-purity version—even if the difference in dose is pretty small.