We Asked a Dietitian How Often You Should Eat Fish for Omega-3s

Fatty fish are a good source of omega-3 fatty acids, but that doesn’t mean you have to eat seafood every day. We asked Grace A. Derocha, MBA, RD, CDCES, a Detroit-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics, how often you should really eat fish to get the omega-3s you need for your body.

*This interview has been edited and condensed for clarity.

Q: How important is omega-3 in our diet? Is fish the best way to get this nutrient, and how often should I include fish in my meals?

Derocha: Omega-3s are important because they are considered an essential fatty acid, which means the body doesn’t make them itself.

Omega-3s help reduce inflammation, lower triglycerides, and support healthy blood pressure by keeping your arteries flexible. Think of it as those fatty acids from omega-3 oiling your heart to help avoid things like atherosclerosis and heart disease.

Fatty fish are the easiest way to get omega-3 fatty acids, but there are great plant-based sources as well, such as powdered flax seeds, soybeans, chia seeds, and walnuts.

The American Heart Association recommends consuming about two 3.5-ounce servings of fatty fish a week. This provides a consistent source of the essential omega-3 fatty acids, both EPA and DHA, which play key roles in heart, brain, and eye health. 3.5 ounces is about the size of a big cell phone or a checkbook.

You can use the acronym SMASH to remember which fatty fish have a good amount of omega-3 fatty acids. SMASH means salmon, mackerel (Pacific), anchovies, sardines, and herring.

Variety adds different options, and all the fatty fish in the SMASH acronym have both EPA and DHA. But getting some fish is better than not getting any. If salmon is what you like, and that’s where you want to get it from, and you are getting your twice-a-week fish in, I would say, do it.

Should I Worry About Mercury Poisoning?

Mercury is a valid concern, especially for certain people, like pregnant people, women who are breastfeeding, and younger children, since it can affect the development of the baby’s brain and nervous system. 

The good news is that the most commonly eaten fish in the U.S. are lower in mercury and high in benefits. The SMASH fish are cold water fish that are safe and smart choices that are lower in mercury and higher in omega-3s.

Shark, swordfish, king mackerel, and tilefish are some to limit or avoid because they’re higher in mercury. Regular, small mackerel have less mercury because they’re so small—they’re the ones that you see in “Finding Nemo.” But king mackerel tend to hold more mercury because they’re bigger.

What If I Don’t Like Eating Fish at All?

Whole fish and actual food itself are best for most people. Eating fish not only gives you omega-3s, but high-quality protein, some vitamin D, selenium, and other heart-healthy nutrients that supplements can’t ever fully replicate. 

That being said, omega-3 supplements, like fish oil, krill oil, or algae oil for people who are vegan, can be a helpful supplement for people who don’t eat fish, might be allergic to some fish, or have a higher need for omega-3s due to heart disease, high triglycerides, or other heart conditions.

When looking for an omega-3 supplement, check for third-party testing for purity and potency, so the marketed ingredients and amounts in it are verified and tested. Look for at least 500 to 1000 milligrams combined of EPA and DHA per serving, which could be one or two pills.