You can safely eat fish and shellfish 3+ times per week, every week. Let me explain.
When I was pregnant with my first daughter, Grace, my husband and I went to Tokyo for a work trip. I was about 24 weeks along and at our first hosted dinner, we were taken to an incredible sushi restaurant. When I said that I couldn't have any raw fish the entire table looked at me like I must have been kidding. The Japanese hosts, both men and women, said that if anything you eat more fish and sushi when you are pregnant, because it helps the baby and the pregnancy. They couldn’t understand why I was removing this essential food from my pregnancy diet. I do understand the concern about undercooked or mishandled sushi and food poisoning, that is a legitimate concern. But mercury? It’s misunderstood. I ate sushi at dinner, and through the rest of the trip. Gracie is a healthy, smart and strong girl, I promise!
What is Mercury?
Mercury is a naturally occurring element in the air we breathe, the water we drink and the food we eat. It’s one of the only elements that is liquid in stable conditions and is beautiful with its shiny silver coloring - which is why it's also known as quicksilver. It comes in various forms: elemental (metallic) and inorganic (to which people may be exposed through their occupation); and organic (methylmercury, to which people may be exposed through their diet). These forms of mercury differ in their degree of toxicity and in their effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes.
The type of mercury that appears in the food we eat, particularly fish, is called methylmercury.
How does Mercury get in fish?
Fish living in the oceans are exposed to mercury through the ocean sediment. Volcanic reactions under the ocean floor release mercury, and even on dry land, nutrient-rich soil full of elements can be found near tectonic plates. Mercury can be released in the atmosphere from things like mining and concrete production. Streams and rivers can also wash mercury into the ocean from the soil. The ocean is constantly performing an incredible air-water exchange and is able to store many elements from our atmosphere.
Once in the ocean, microorganisms like phytoplankton consume and transform the mercury into methylmercury. This is the form that we consume through food. Small fish eat those plankton. Larger fish eat the smaller fish. Huge fish eat the larger fish, and up the chain we go. This accumulation of mercury up the food chain is called “bioaccumulation”. This is why you’ll notice that larger fish that live longer tend to be on the “consume sparingly” lists.
How much Mercury can I safely eat?
Currently, the EPA’s reference dose — the figure the FDA and EPA both build their fish advice on — puts what humans can safely tolerate at an average of 0.7 ug of mercury per kilogram of body weight per week. I know, math. This means that some weeks you’ll have more mercury than others, remember, it's an average.
Lemme make it easier:
100 lbs = 32 ug Mercury per week
130 lbs = 41 ug Mercury per week
150 lbs = 48 ug Mercury per week
160 lbs = 51 ug Mercury per week
170 lbs = 54 ug Mercury per week
180 lbs = 57 ug Mercury per week
190 lbs = 60 ug Mercury per week
200 lbs = 64 ug Mercury per week
210 lbs = 67 ug Mercury per week
220 lbs = 70 ug Mercury per week
230 lbs = 73 ug Mercury per week
*You can do more math if your weight is missing.
One caveat before you use that table: those are general-population numbers. If you are pregnant or breastfeeding, the FDA and EPA give you your own guidance — 8 to 12 ounces of lower-mercury seafood a week — and I have written that up properly in Seafood and Pregnancy Nutrition. My Tokyo story is about seafood belonging in a pregnancy diet, not about ignoring the specifics.
As an example… at 160 lbs, I can have 51ug of mercury each week. Here is what that actually buys me. Two Sockeye Salmon dinners, a Wild Alaska Cod dinner, a plate of Spot Prawns and a pan of Weathervane Scallops — five seafood meals — and I am at about 32 ug. Add a Dungeness Crab feast and I am at about 43, still under. Six seafood meals in one week. You have to work fairly hard to run out of room at the low-mercury end.
If I was on a sockeye kick I could have one of our 6 oz Sockeye Salmon portions five nights a week and still be at about two thirds of that weekly figure. Here is the part you will not find on most mercury charts, though: not all salmon is the same. Alaska tests its salmon species separately, and King comes in about 60% higher than Sockeye — 0.062 parts per million against 0.038. Both are still low-mercury fish by any standard, but it does show up in the arithmetic. In the same 160 lb example, four 6 oz King Salmon portions work out to about 83% of the weekly reference-dose figure, and five put you just past it.
Where it pays to plan a little is with two of our items: our Wild Albacore Tuna and our Wild Pacific Halibut. Those two sit highest in mercury of anything we sell. A whole 6 oz can of albacore would use up a 160 lb person’s entire weekly allowance on its own, so a tuna sandwich made with half a can is the sensible unit — and that still leaves room for two or three sockeye dinners. A 6 oz halibut portion comes to about four fifths of a week’s allowance, which leaves room for one sockeye dinner on top.
For context on how the agencies sort this: salmon, cod, shrimp, scallops and crab all sit on the FDA’s “Best Choices” list at two to three servings a week, while albacore, sablefish and halibut sit in “Good Choices” at one serving a week. Worth knowing that the FDA’s serving is 4 ounces, so one of our 6 oz portions is about one and a half FDA servings.
Sablefish is the interesting case, and I want to be straight with you about it. Alaska has tested 243 Alaska-caught sablefish and puts the median at about 0.11 parts per million, which would place it alongside our cod — two portions a week fits comfortably. The FDA’s national figure is about three times higher, at 0.361, and that is why the FDA files sablefish with the “Good Choices.” The FDA number is an average of 26 samples from unspecified waters; Alaska’s is a median from 243 fish caught where ours are caught. I have used Alaska’s, because it describes the fish we actually sell — but if you would rather follow the federal framing, treat sablefish as your one Good Choice serving for the week.
One more thing, and it is the part nobody mentions: size matters more than species. Within a single species, a big old fish can carry ten times the mercury of a small young one — Alaska’s testing puts halibut under 20 pounds at about 0.12 parts per million and halibut over 220 pounds at about 1.2. I will be honest that I cannot tell you which end of that range any individual portion came from, ours included. It is one of the reasons I would rather eat a variety of species across a week than a lot of any single one.
If you want to check my arithmetic, here is where these numbers come from. The weekly allowance is the EPA’s reference dose for methylmercury, 0.1 ug per kilogram of body weight per day, which is the 0.7 ug per kilogram per week I used above. For salmon, cod and sablefish I have used Alaska’s own testing — 0.038 parts per million for sockeye, 0.062 for king, 0.10 for Pacific cod and 0.11 for sablefish — because Alaska tests Alaska fish, separates the species and works from far larger samples than anyone else. For halibut, crab, shrimp and scallops I have used the FDA’s monitoring of commercial fish and shellfish. For our canned albacore I have used 0.335 parts per million, the mean Oregon State University reported in 2025 from testing four brands of commercially canned Northeast Pacific troll-caught albacore — the same fishery ours comes from, though not a test of our own fish. Where the numbers differ I have said so rather than picking quietly. And if you want to play the “how much mercury does this have in it” game yourself, here is a very cool calculator. Pssst… there is a note on selenium below too.
How does the body get rid of mercury?
Mercury is metabolized through a reaction called “redox” you learned about in school way back when! The oxidation–reduction cycle takes place in our gut microbes and after absorption in many tissues and in the red blood cells. This means that electrons are being exchanged in order to break it down to a form that can then be excreted (mostly out the other side of our intestines into the toilet).
A Major Note about Selenium…
Selenium is another chemical element that works as a nutritional mineral. It is found in very small amounts of food and I would argue that many of us do not get enough selenium in our everyday diets. It comes up here because selenium and mercury bind to one another, and researchers have spent years investigating whether that changes how mercury behaves in the body.
What we can say is what has actually been measured, and it is genuinely striking. Alaska’s Department of Environmental Conservation has tested thousands of Alaska fish for both minerals and found a selenium surplus in every commercially important species it looked at — often several selenium atoms present for every mercury atom. Our sockeye carries about 40 micrograms of selenium in a 3 oz serving, halibut about 47, king crab about 34, against an adult daily requirement of 55. When Oregon State tested canned Northwest troll-caught albacore in 2025, selenium ran 0.569 to 0.649 parts per million, four to five times the mercury on a molar basis.
What I am not going to tell you is that selenium cancels the mercury out. The binding is real and the laboratory work is interesting, but it has been shown in cells and in animals, not demonstrated in people — and no health authority anywhere adjusts its fish advice for selenium content. So treat selenium as one more reason seafood is nutritionally outstanding, and keep using the numbers above.
For a sense of scale, it is worth looking at one of the foods richest in selenium: the Brazil nut. The NIH puts a single nut at 68 to 91 micrograms — more than an adult’s 55 microgram daily requirement in one bite — and an ounce of them at around 544 micrograms.
What makes them genuinely fascinating is how much they vary. Brazil nuts draw selenium from the soil they grow in, and Amazonian soils differ enormously. When researchers sampled 71 trees across five Brazilian states, the median selenium ran from 2.4 milligrams per kilogram in Mato Grosso to 66.1 in Amazonas — more than twentyfold between regions, with individual samples spanning less than 0.5 up to 146.6. Their conclusion was that one nut might deliver anywhere from 11 percent to 288 percent of a day’s selenium depending on where it grew. Another study found an eightfold difference between individual nuts from the same batch. So there is no such thing as “the” selenium content of a Brazil nut.
Which is exactly why I mention them as a comparison rather than a recommendation. Selenium is a mineral where more is not better: the adult upper limit is 400 micrograms a day, and Brazil nuts can reach it faster than anything else in the pantry — the NIH specifically warns they could cause selenium toxicity if eaten regularly. Enjoy them as the remarkable thing they are, get your selenium from food across your week rather than from a supplement strategy, and do not treat them as something you take to offset mercury. That is not how any of this works.
Can I test myself for Mercury?
Yes, but it’s not really helpful for most of us. Methylmercury (organic mercury) accumulates in our bloodstream and urine, and overtime in our hair follicles. The best measurement for recent exposure would be a blood test through your doctor… but they rarely ever order them. A hair test would be a better long term indicator. Red blood cells turn over about every 30 days, so a blood test would be an accurate snapshot looking about the past month of dietary intake. The only reason you would do this would be if you had a drastic increase in consuming foods like mackerel, swordfish, tilefish or bigeye tuna specifically; or if you are having symptoms of heavy metal toxicity, such as unexplained and chronic nausea and vomiting, diarrhea, stomach pain, brain fog and fatigue.
At home mercury test kits don’t really apply here. They mainly test for elemental mercury (inorganic and metallic) which would come from toxic exposure via workplace heavy metals. If you do test for mercury, remember that mercury from the diet is methylmercury (organic mercury) and many tests will report on other forms (elemental, inorganic) as well - which would not have come from food. Be sure to read carefully.
One last piece of context, and it is the one I find most reassuring. Alaska monitors its own seafood more closely than almost anywhere — over a thousand halibut, hundreds of sablefish and Pacific cod — and the State of Alaska’s advice for adult men and for women not at risk of pregnancy is unrestricted consumption of all fish from Alaska waters, with one exception, salmon shark, which we do not sell. For women who are or may become pregnant, nursing mothers and children, Alaska puts all five salmon species and Pacific cod in its unrestricted category and gives specific meal guidance for the larger fish. Alaska’s framework is deliberately different from the federal one: it weighs the benefits of eating fish alongside the contaminant risk, where, in Alaska’s words, the federal framework “often does not consider the benefits that co-occur with exposure to a contaminant.” Both are worth knowing about. Neither one says to eat less seafood.
In conclusion - please eat seafood every week! The benefits of protein, omega-3s, and trace minerals far outweigh any risk associated with the mercury content!
Key Facts:
- The type of mercury matters. We get a specific type called methylmercury from eating fish.
- Ethylmercury is a different type of mercury that can be found in small amounts in vaccines - this type of mercury is very different and does not accumulate in the body and is very safe.
- Half of the mercury produced in the atmosphere comes from us humans. Reducing how much mercury we put into the atmosphere will significantly reduce the amount that makes it into fish and our food supply.
- Humans contribute to mercury in the atmosphere by burning fossil fuels like coal, mining for things like gold, and concrete production. By far, burning coal is our greatest contributor.
- Our bodies can handle and metabolize mercury! There is plenty of room for seafood in your diet every single week.
- Seafood is a very rich source of selenium, an essential mineral — and selenium and mercury do bind to one another, though what that means for people is still being researched.