Mercury is a biotoxin that can clog up the brain, liver and kidneys. Many consumers are rightfully concerned about the potential for mercury exposure from seafood. When we mention our albacore tuna, mercury is a common concern we hear back from our customers.
In this blog post, we will try to allay some of these concerns regarding mercury. At a high level, there are 2 main key points we’ll try to make: 1) the Alaska seafood we sell is not known as having high levels of mercury; 2) many species of seafood have very high levels of selenium, a mineral known to counteract the negative impacts of mercury. Selenium also has a number of really important antioxidant properties that help immune function and create better aging, along with a long list of other benefits that we go through below.
Lastly, perhaps the key benefits of eating seafood are that those who consume it live longer and happier. Indeed, seafood consumption during pregnancy and childhood is linked to improved brain development and positive neurodevelopmental outcomes and we share several studies that illustrate the power of seafood in neurodevelopment. Populations that consume the most seafood, like those in Scandinavia, the Mediterranean, and Japan are among the longest-lived populations on the planet and are without negative brain development impacts.
But let’s start with the basics.
What is mercury?
Mercury is a toxin that attaches to fatty tissues and competes for cellular binding sites with other key minerals.
Sources of mercury include dental fillings, processed foods, cosmetics, lotions, sometimes air and water, some vaccines, pollution, and unfortunately seafood. Mercury tends to build up over time, so fish species that are especially long lived or species at the top of the food chain tend to have higher levels of mercury. Long-lived larger species like swordfish, tilefish and shark are known to have higher amounts of mercury compared to other species.
Mercury danger levels in seafood
In general, ocean fish contain higher amounts of selenium than mercury levels.
The chart below looks at mercury levels in Alaskan seafood. 1.0 mg / Kg is the FDA action level for mercury content whereas 0.2 mg/Kg is the unrestricted consumption amount for women and children.
Chart courtesy of Alaska Seafood
Our Alaska salmon is well below the 0.2 mg/ Kg unrestricted consumption for women and children. Our canned albacore tuna tests at 0.309ppm, well below the FDA action level as well.
What is selenium? What are its benefits for our bodies?
Selenium is a trace mineral that incorporates into proteins to selenoprotein enzymes that function as antioxidants in our bodies to destroy free radicals, boosting our immune system. The antioxidant properties of selenium protect cells from damage caused by free radicals like mercury. Selenium works like a mercury hoover that binds to and then redistributes and eliminates toxic mercury from our bodies. Selenium removes mercury from the body in a process known as methylation, which is a chemical reaction that changes the structure of mercury, making it easier for the body to excrete mercury. Another key benefit of these selenoprotein enzymes is help with thyroid function. Selenium helps produce thyroid hormones that regulate metabolism.
Selenium removing mercury from the body is a key benefit and we should try to maintain a surplus balance of selenium over mercury. The recommended daily amount of selenium consumption per day is 55 mcg for adults 60 mcg for pregnant women, and 70 mcg for breastfeeding women.
Beyond functioning as a hoover for mercury, selenium has a number of other key benefits, including the ability to increase antioxidants’ capabilities in our bodies, improving blood flow, and lowering inflammation. The antioxidant properties of selenium repair damaged cells which can also reduce cancer growth and improve our bodies’ aging process. Selenium also improves both male and female fertility.
Seafood consumption during pregnancy and childhood
The benefits of eating seafood, like the forementioned selenium content in ocean fish like salmon, halibut and tuna, far outweigh the risks from mercury toxicity. A review of studies found that eating seafood during pregnancy and during childhood is associated with improved brain development. No negative impacts on neurocognitive outcomes were found, despite potential exposure to mercury, even in a long-term study that followed children who ate ocean fish almost every day. Another study found that pregnant women who ate less than 12 ounces of seafood per week had children with increased developmental delays and lower IQ scores. A common thread in these studies is that advice to limit seafood consumption during pregnancy is actually detrimental for developing babies.
Recommendations for getting enough selenium in your diet
Beyond Brazil nuts, which are said to have enough of the recommended daily consumption of selenium in just 6 nuts or so, many species of seafood are very high in selenium, particularly cold-water fish like wild-caught salmon, albacore tuna, and halibut.
Wild-caught salmon has between 30-40 mcg per 3-ounce serving while halibut has 47 mcg and rockfish has 65 mcg per 3-ounce serving.
So, at the end of the day for Alaska seafood and our albacore tuna, it is the case that the benefits far outweigh the perceived risks. There are so many other benefits of Alaska seafood--high-quality protein with vitamins and minerals--that we highlight throughout our website.
