Good Fish, Bad Fish
Generally, fish has been lauded as a smart choice for the health conscious individuals. Studies show that people who eat fish live longer than those who consume red meat, especially cured or smoked meats. As a rule, the oilier the fish the healthier; and choosing wild caught fish is a better choice than farmed fish.
Mercury is a heavy metal found in our oceans put there from pollution. As the mercury lingers in the waters and on the ocean’s plants, fish consume it. Larger fish eat the smaller fish and so on. But mercury is not digested by fish so the mercury stays in their bodies, accumulating over time until we catch the fish and eat it, hence eating the mercury. In general, the older the fish the more likely it is to contain high levels of mercury.
Mercury is a health risk. It causes brain damage as it builds up in our body just like it does in the fish. It causes even more damage to the brain and nervous system of a developing baby in a mother’s womb (uterus) prior to birth. Studies have shown a decrease in the IQ’s of babies born to mothers who consumed fish containing mercury. The damage to the baby’s IQ is directly related to the amount of mercury exposure, the more mercury the more brain damage.
The dangers of mercury should not be taken lightly. Even though the EPA lists recommendations for limiting consumption of certain kinds of fish, a safe limit of mercury consumption cannot be calculated. It is therefore prudent not just for children and pregnant woman to avoid mercury containing fish but also for non-child bearing woman and, yes, men to avoid eating mercury laden fish.
Tuna has been commonly thought to be the worst fish for mercury content and many people think it is the only bad fish. But is tuna really the worst one?
The following list was developed by the Environmental Protection Agency (EPA) and shows the types of fish that a woman who is pregnant or planning to become pregnant can safely eat and how much. The EPA recommendation is based on body size. The suggestions below are based on a 6 ounce serving of cooked fish for a 130 pound woman; adjust portion sizes based on weight for children. Adult men (hopefully not pregnant), and women who are not planning to become pregnant, are less at risk from mercury exposure but use this list to find low-mercury fish choices. Again I feel this list should apply to everyone and as a rule, it’s always best to pick fish only from the green list.
Avoid eating these.
The highest levels of mercury are found in these six fish species:
Shark, Swordfish, King Mackerel, Tilefish Marlin, Orange Roughy, Tuna (Bigeye, Ahi)
Eat three servings or less per month.
Moderately high levels of mercury are found in the following fish species:
Albacore Tuna, Yellowfin Tuna, Bluefish, Grouper, Mackerel (Spanish, Gulf), Sea Bass (Chilean)
Limit the following to six or less servings per month.
Lower levels of Mercury and safer than the ones above:
Bass (Striped, Black), Carp, Cod (Alaskan), Croaker (White Pacific), Halibut (Atlantic), Halibut (Pacific), Jacksmelt, Lobster, Mahi Mahi, Monkfish, Perch (Freshwater), Sablefish, Skate, Snapper, Tuna (Canned chunk light), Tuna (Skipjack), Weakfish (Sea Trout)
The least/negligible amounts of Mercury are found in the following species:
Alaskan Salmon, Black Cod, Sardines, Oysters, Shrimp(non-farmed), Scallops, Squid (Calamari), Anchovies, Butterfish, Catfish, Clam, Crab (Domestic), Crawfish/Crayfish, Croaker (Atlantic), Flounder, Haddock (Atlantic), Hake, Herring, Mackerel (N. Atlantic, Chub), Mullet, Perch (Ocean), Plaice, Pollock, Shad (American), Sole (Pacific), Tilapia, Trout (Freshwater), Whitefish, Whiting
Action Item: Even though the EPA lists the above recommendations and based on my review of the literature given that studies have shown a decrease in the IQ’s of babies born to mothers who consumed fish containing mercury and the damage to the IQ is linearly related to the amount of mercury exposure. A safe limit of mercury cannot be calculated. It is therefore prudent before during pregnancy to eat fish only from the green list above. Children, non-child bearing women and men should also pick from the green list. Remember always seek the advice of your primary care provider for health advice.
One study performed in Massachusetts “higher fish intake was associated with better child cognitive test performance, and higher mercury levels with poorer test scores” leading researchers to state, “Dietary recommendations for pregnant women should incorporate the nutritional benefits as well as the risks of fish intake”.
There is little awareness amongst women of child-bearing years as to the effects of mercury and its presence in some fish:
Mixed messages: Consumption of at least two servings of fish per week is recommended by the American Heart Association (AHA) to help protect the heart. Some fish are contaminated with methyl mercury, which may counteract the positive effect of the omega-3 fatty acids, and numerous governments have issued advisories for certain fish species. It is important to understand the list above to be educated to protect you and your family.
Please visit the NRDC mercury calculator for mercury calculations based on portion size and fish type:
For more information on mercury in fish please visit this guide: