Chances are you’ve got some cans of tuna in your pantry. It’s a great staple to have on hand and is a convenient source of protein and other nutrients, but as some people are having a tuna sandwich every day now that they’re working from home (hey, it’s convenient)  it raises a good question: How much is too much seafood? Do you need to worry about mercury poisoning? Here’s the skinny on seafood consumption.

Why Eat Seafood in the First Place?

This post isn’t about the health benefits of seafood but I should mention why people choose to eat it in the first place if I’m going to talk about recommendations. Seafood is the best source of omega-3 fatty acids, specifically docosahexaenoic acid (DHA), an essential fatty acid that’s been shown to reduce inflammation, heart disease, and certain cancers; support muscle recovery after exercise; help prevent or slow Alzheimer’s disease; support brain function and fertility.  There are other nutrients such as protein and B vitamins but the unique benefit of seafood is the DHA content, you can’t get that in appreciable amounts in other foods.


Salmon is a great source of DHA, an essential fatty acid.

Why Limit Seafood?

Some types of fish can contain high levels of mercury, a toxic heavy metal. Mercury is found naturally in the air, water, and soil. Algae and other sea plants absorb mercury. Fish then eat the algae, absorbing it and retaining the mercury. Larger fish then accumulate higher mercury levels from eating smaller fish, which ate the algae that contained mercury. This is known as bioaccumulation. We eat the fish and the same thing happens to us, we absorb the mercury and it accumulates in our body.

Why Seafood is Especially Important for Athletes

When you exercise you generate free radicals that can cause oxidative damage. If you don’t have the right nutrients in the right amounts, your body has a hard time putting out the fires per se. Omega-3 fatty acids are important in regulating the inflammatory pathways and help your body modulate the inflammation. Because athletes generate more inflammation, I/research suggest(s) athletes consume more omega-3 fatty acids. I like avocado and walnuts as much as the next person, but plant forms don’t have DHA, the omega-3 fat in your brain that helps with brain function and has been shown to improve inflammation.

Can’t I Just Take A Fish Oil Supplement?

In a word, no. Taking a supplement is not the same as consuming fish. The research is rather conclusive on whole foods being superior for all nutrients (except folic acid, but that’s another story).  Not to mention you will get a whole host of other nutrients besides just the fish oil when you eat seafood. If you don’t like seafood I encourage you to try some you’ve never had before or cook it a different way. Try baking, broiling,  steaming, or sautéing.

Key Takeaway:


After going through the research, good evidence suggests the health benefits of eating seafood far outweigh the risk of mercury poisoning. You shouldn’t be afraid of eating seafood, especially if you follow the recommendations below. Nothing in life has zero risks. We always have to take on some degree of risk in our actions, and eating seafood is no different.

Here are some guidelines to minimize any risk and get the most nutrients out of your delish fish.

  • Eat 2-3 servings (227-340g) of seafood per week  
  • Choose lower-mercury fish and seafood such as salmon, shrimp, sardines and cod (see list below)
  • Light tuna has less mercury than albacore tuna (I prefer chunk light, it mixes nicely in salads and other dishes) so opt for light when choosing a canned option
  • Avoid high mercury fish such as shark, swordfish and king mackerel

Mercury Content of Fish 

Not all seafood is created equal. Here’s the mercury content in parts per million (ppm) in order of most to least mercury. 

  • Swordfish: 0.995 ppm
  • Shark: 0.979 ppm 
  • King mackerel: 0.730 ppm
  • Bigeye tuna: 0.689 ppm 
  • Marlin: 0.485 ppm
  • Canned tuna: 0.128 ppm
  • Cod: 0.111 ppm
  • American lobster: 0.107 ppm 
  • Whitefish: 0.089 ppm
  • Herring: 0.084 ppm 
  • Hake: 0.079 ppm
  • Trout: 0.071 ppm
  • Crab: 0.065 ppm 
  • Haddock: 0.055 ppm 
  • Whiting: 0.051 ppm
  • Atlantic mackerel: 0.050 ppm
  • Crayfish: 0.035 ppm
  • Pollock: 0.031 ppm
  • Catfish: 0.025 ppm
  • Squid: 0.023 ppm
  • Salmon: 0.022 ppm
  • Anchovies: 0.017 ppm
  • Sardines: 0.013 ppm
  • Oysters: 0.012 ppm
  • Scallops: 0.003 ppm
  • Shrimp: 0.001 ppm

About Dr. A’nna

Dr. A’nna strives to inspire people to optimally fuel their body to achieve their best and have a positive impact on the world. She is the only combined Ph.D./RD specializing in sports performance nutrition in the world with all Ivy League degrees and the Chief Research Officer at AthleteBloodTest.

Dr. A’nna aims to cultivate a world of healthy athletes who understand nutrition and know how to leverage their physiology to get the best results in sports and life. You can reach her at [email protected] or on instagram @iron_sage_consulting.

Categories: Nutrition