When it comes to eating for longevity, doctors and dietitians regularly wax poetic about the importance of getting your fill of both plants and fish—and for good reason. While plant-based foods are packed with nutritional value, there is one key nutrient it’s hard to get from them: omega-3 fatty acids. Scientific studies continue to prove that omega-3s in particular are linked to living a longer life.

There are plant-based foods that do contain this nutrient, but omega-3 fatty acids are found more abundantly in fish—along with vitamins D and B2 as well as protein, calcium, phosphorus, iron, zinc, iodine, magnesium, and potassium. Quite a resume, right? But when it comes to the absolute best fish for longevity, nutrition expert Maya Feller, RD, says there’s a specific type to keep in mind next time you’re hitting up the fish market. You ready for it? SMASH fish.

What SMASH fish stands for

Before you go off and running (swimming? fishing?), know that SMASH fish is not some new species being bred in secret Alaskan coasts. Rather, it’s an acronym for salmon, mackerel, anchovies, sardines, and herring. In other words, the word “SMASH” is a simple way to remember the five types of fish that are highest in heart-healthy omega-3 fatty acids.

By the way: The SMASH fish-longevity link isn’t something that Feller alone is talking about. These types of fish are cornerstones to diets in every single Blue Zone, aka regions in the world where people regularly live to be over 100 in good health. People who live in Okinawa, Japan, Sardinia, Italy, Nicoya, Costa Rica, Ikaria, Greece, and Loma Linda, California all incorporate SMASH fish into their cuisine; they just do so in different ways.

SMASH fish is not some new species being bred in secret Alaskan coasts; rather, it’s an acronym for salmon, mackerel, anchovies, sardines, and herring. In other words, SMASH is a simple way to remember the five types of fish that are highest in heart-healthy omega-3 fatty acids.

Curious as to why SMASH fish—salmon, mackerel, anchovies, sardines, and herring—are linked to longevity? Prepare to get schooled.

Why SMASH fish are the best fish for longevity and heart health

1. Fatty fish is packed with DHA and AHA omega-3s, which are a boon for heart health

Feller says there are several reasons why SMASH fish have such a strong link to longevity over other types of fish. One reason is that they are extremely nutrient-rich and particularly high in the aforementioned heart-supporting omega-3s. “Our bodies can’t make omega-3 fatty acids, so we must get this nutrient from food,” Feller explains. “The reason why omega-3s are linked to longevity is because they’re involved in many systems within the body including brain health, the central nervous system, and cardiovascular health.”

The connection between omega-3 fatty acids and heart health is especially noteworthy since heart disease is the number one cause of death in the U.S. Eating SMASH fish twice a week is linked to lowering this risk.

The connection between omega-3 fatty acids and heart health is especially noteworthy since heart disease is the number one cause of death in the U.S. Eating SMASH fish twice a week is directly linked to lowering this risk.

2. They’re loaded with essential nutrients that help reduce oxidative stress

Besides omega-3 fatty acids, Feller says SMASH fish are a lean protein source and have a long list of other nutrients, including selenium (linked to reducing your risk of heart disease, age-related mental decline, and oxidative stress) and vitamin D (linked to lower rates of chronic health concerns, including cancer).

3. They contain lower mercury levels than other types of fish

Feller says that another major reason why SMASH fish reign supreme in terms of the best fish for longevity is because they pack all this nutrient value while having low mercury levels. “Mercury [a neurotoxin] is caused by pollution and can negatively impact the brain and nervous system, and unfortunately, it’s in really all fish,” Feller explains.

Feller says that the bigger the fish, the more likely it is to have a higher mercury level. “This is because big fish eat smaller fish, absorbing the mercury from those fish,” she says. Fish that tend to have higher mercury levels include tuna, bluefish, grouper, marlin, king mackerel, shark, and swordfish. (With mackerel, mercury levels can vary by variety; Atlantic and Atka mackerel from Alaska, for instance, are low in mercury.)

The fact that SMASH fish pack in a lot of nutrient density while having lower levels of mercury than other fish is exactly what makes them a longevity win.

How much SMASH fish should you eat?

The American Heart Association recommends eating a serving of SMASH fish twice a week for optimal cardiovascular health.

Tips for buying and eating SMASH fish

Okay, so you know what types of fish are most strongly linked to longevity and why, but actually buying them and knowing how to eat them are important, too.

Check the ingredients

You may have seen sardines, anchovies, herring, and mackerel show up in the canned foods aisle. Does buying it this way instead of at the fish market get Feller’s dietitian seal of approval? It sure does. “You just want to make sure you pay attention to the ingredients list,” she says. “The ingredients should just be the fish, olive oil, water, and salt. Also, eye the sodium content to make sure it’s not too high.”

Purchase sustainably-sourced fish whenever possible

Whether you’re buying your SMASH fish fresh or in canned form, Feller says it’s also important to look for labeling indicating that it is sustainably sourced. The big one to look for is the Marine Stewardship Council, which takes into account codes and guidelines provided by the UN Food and Agriculture Organization (FAO), ISEAL, and the Global Sustainable Seafood Initiative (GSSI). The Aquaculture Stewardship Council, which is an independent non-profit that has a certification for fish farms, is another label that indicates sustainable sourcing.

Delicious ways to prepare and serve SMASH fish

In terms of how to eat your SMASH fish, Feller says there is no shortage of ways. She explains that eating a variety of nutrient-rich foods is best for health, so if you’re in the habit of eating just one type of SMASH fish (like, you know, salmon?), see this as an opportunity to branch out.

“Many days for lunch, I’ll have salted crackers with sliced of sweet onion, cucumber, and tomato, and either sardines or anchovies,” Feller says. “Another great way to enjoy these types of fish is by chopping them up and mixing them with rice and your favorite spices.” She also says they can be chopped and worked into tomato sauce for pasta.

If you’re feeling timid, Feller says to try one of the fish you haven’t eaten before with foods you already love. That way, you’re pairing it with something you’re comfortable with and not eating a completely new dish. And of course, the Internet is full of SMASH fish recipes, too.

“Many days for lunch, I’ll have salted crackers with sliced of sweet onion, cucumber, and tomato, and either sardines or anchovies,” Feller says.

What’s most important is to keep an open mind and making a conscious effort to work SMASH fish into your diet more, ideally twice a week. Once eating these little fishies becomes a habit, you’ll sea the results first-hand for many (many) years.

A dietitian’s favorite foods packed with vitamin D:

—reviewed by Jennifer Logan, MD, MPH