Sure you've heard eating fish is good for you. You may have even heard fish oil is good for your heart. But not all fish and fish oil is created equal!
Why is fish good for your heart?
We've known for quite some time that eating fatty fish a couple times a week is good for health. We now know that's probably in large part due to the omega-3 fatty acid content of those fish. Omega-3 fatty acids are a type of polyunsaturated fat that are considered essential fatty acids, meaning humans must consume them because we can't make them on our own. There are several types of omega-3s, including ALA, EPA, and DHA. Of the three, only ALA is essential, and the recommended daily intakes use ALA amounts. The human body can make EPA and DHA from ALA. However, most experts agree that consuming omega-3s as EPA and DHA is a more reliable way to reach recommendations (1).
Omega-3 fatty acids function mainly by reducing inflammation. They do this by reducing the amount of arachidonic acid in inflammatory cells, platelets, and endothelial cells, thereby reducing their inflammatory actions (3). Omega-3s also reduce the transcription of cytokines, another type of inflammatory molecule (2).
Many fish are high in omega-3s, and eating them has been linked to decreased coronary heart disease (CHD), including fatal CHD, myocardial infarction, and sudden cardiac death (2).
Is fish oil just as good as eating fish?
If fish is so good for our heart, it seems logical that fish oil would be just as good, right? Well, it turns out that fish oil doesn't show such robust heart healthy benefits when it's put to the test (4, 5). Research shows that fish oil may have some benefit in preventing future heart events if you've already had one (heart attack, stroke, etc.), and may help reduce high LDL levels (2), but it's not as useful for people who are healthy and looking for prevention. In all cases, consuming actual fish is better. Supplements are only meant to fill in gaps; not replace healthy eating habits.
What is the best fish for heart health?
As we said at the beginning, not all fish is created equal! To reap the most heart benefits from your fish, it's important to choose so-called "fatty fish." These are fish species that live in colder waters, and need an extra layer of fat to keep them warm. That fat layer is what is rich in omega-3 fatty acids. In general, farmed fish has more omega-3s than wild caught, but may also be higher in pollutants. Fish farming can also take a toll on the environment if not done responsibly. To learn more about how responsibly and sustainably your favorite seafood is farmed or caught, and to find better choices, visit the Monterey Bay Aquarium's Seafood Watch.
The fish with the highest concentration of omega-3s are (6):
- Salmon (Atlantic, Chinook, and Coho are highest)
- Mackerel
- Sardines
- Arctic Char
- Sablefish (AKA Black Cod)
- Bluefin Tuna
- Rainbow Trout
- Anchovies
- Herring
What is the worst fish for heart health?
On the flip side, not all fish are high in omega-3s. Here is a selection of seafood lowest in omega-3 fatty acids (6):
- Crabs
- Clams
- Orange Roughy
- Atlantic Cod
- Tilapia
- Yellowfin Tuna
- Shrimp
- Catfish
- Mahi mahi
- Ocean Perch
- Pollock
How much fish should I eat for heart health?
Eating two servings of fatty fish per week, or about 250-500 milligrams of omega-3s per day, has been linked to the highest heart health (7), and is also what the American Heart Association recommends. Eating more than that is not associated with more protection. Two servings of about 3.5 oz each, per week seems to be the sweet spot.
If you already have heart disease, then 1 gram/day (1000 milligrams) of omega-3s is recommended (8), from the consumption of fatty fish, a fish oil supplement, or both. Remember to run it by your doctor before starting any new supplements!
What about mercury in fish?
Mercury is a huge concern when it comes to seafood. Mercury stays in an animal once it's ingested, and it tends to bioaccumulate. That means the higher you go in the food chain, the more concentrated it tends to be. There is a little mercury in algae, a little more in the little fish that eat it, more still in the bigger fish that eat those little fish, and the most in sharks and whales that eat the big fish. A simplistic example, but you get the picture.
For most people, the benefits of consuming seafood outweigh the risk posed by mercury (9). Still, it's important to choose fish low in mercury, especially for children and pregnant women. Eating a variety of fish and seafood can also help ensure lower mercury exposure. Seafood with higher levels of mercury include:
- Sharks
- Tilefish
- Swordfish
- King mackerel
Seafood with lower mercury levels include:
- Salmon
- Pollock
- Catfish
- Light tuna (canned)
- Shrimp
Is there an alternative to eating fish?
For those who don't like, or don't want, to eat fish, or who are allergic to seafood, there are some good plant sources of omega-3s. After all, that's where the fish get it in the first place! Plant sources do contain omega-3s mostly in ALA form, which the body uses less efficiently, but it is still possible to reach recommendations with diligence. The highest plant sources of omega-3 fatty acids, in decending order, are (6):
- Flaxseed oil
- Chia seeds
- Walnuts
- Flax seeds
- Canola oil
- Soybean oil
- Soybeans/Edamame
Algae oil supplements and krill oil supplements are alternatives to fish oil (note that krill is not a vegetarian source).
There is ample evidence that including rich sources of omega-3s regularly is important for heart health. Be sure to choose sources you enjoy, since you'll be way more likely to reach recommended levels that way! 🙂 What's your favorite way to get your omega-3s? Tell me in the comments!
Find out what is the best diet for heart disease management!
Are you looking for recipes that have healthy fats? Head over to our recipes with healthy fats index!
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