Dr. Sarah Ballantyne, PhD, also know as “Paleomom” from ThePaleoMom.com says don’t worry about the mercury.
In her comprehensive analysis, Dr. Sarah Ballantyne, PhD, she explains why this is not a real issue and that more fish is better than less. Often, we hear warnings about the dangers of mercury contamination in seafood, with particular caution advised to pregnant women due to potential risks to the developing fetus. These warnings paint a frightening picture, but Dr. Ballantyne’s research suggests that the situation is far less alarming.
Mercury is indeed present in various foods, with concentrations typically low in fruits and vegetables. However, in seafood, particularly certain types of fish, mercury levels can be higher due to absorption from water and the organisms fish consume. The primary form of mercury in fish is methylmercury, concentrated in the muscle rather than the fat. Methylmercury accumulates over time, especially in fish higher up the food chain, a process known as biomagnification.
The concern with methylmercury is its almost complete absorption from the gastrointestinal tract and distribution to all tissues, including its ability to cross the blood-brain barrier and the placenta. High levels of methylmercury can damage the central and peripheral nervous system.
The key to understanding the risks and benefits of seafood consumption lies in the selenium content of the seafood. Selenium, a mineral required for the activity of various enzymes, plays a crucial role in protecting the brain from oxidative damage. Methylmercury binds to selenium, but most ocean fish contain more selenium than methylmercury, making them safe to consume. This higher selenium content means that selenium-bound methylmercury is not efficiently absorbed by our bodies, and what is absorbed cannot interfere with our selenoenzymes.
Fish with very low levels of methylmercury include shellfish, salmon, crab, shrimp, trout, herring, haddock, and others. Most ocean fish and approximately 97% of freshwater fish are safe, with only a few exceptions like pilot whale, tarpin, swordfish, shark, marlin, king mackerel, and tilefish. The Environmental Protection Agency (EPA) is working on assigning Selenium-Health Benefit Values (Se-HBV) to each type of fish, essentially a ratio of selenium to methylmercury content.
Dietary selenium intake is beneficial for protecting against mercury exposure, and it is abundantly found in seafood, seaweed, mushrooms, onions, Brazil nuts, sunflower seeds, and meat and poultry, especially the liver. The majority of fish available in stores or restaurants are safe to eat, with swordfish being a notable exception.
Dr. Ballantyne recommends increasing, rather than decreasing, fish consumption, even for pregnant women. Aiming for three 6oz servings of oily cold-water fish per week, in addition to other fish and seafood types, provides the recommended intake of DHA and EPA. This dietary choice not only addresses concerns about mercury content but also promotes better overall health due to the numerous nutritional benefits of seafood.