Methylmercury in Seafood

What is methylmercury?
Methylmercury is a form of mercury that can be harmful to the developing brains of unborn babies and young children, effecting cognitive, motor, and sensory functions.  The more it accumulates in a person's bloodstream, the longer the exposure time, and the younger in age of the person consuming the fish, the more severe the effects may be.

Who should use extra caution?
If you are a pregnant woman, a woman of childbearing years who may become pregnant, a nursing mother, or a child, the FDA and EPA advise against eating fish that might contain high levels of mercury.  Since it can also effect mean and women of all ages, comsumption of fish that may contain high levels of mercury should be limited to occasional use.

How does it accumulate in fish?
Although mercury occurs naturally in the environment, the primary source of methhylmercury in fish is industrial pollution.  Through rain, snow, and runoff, mercury can accummulate in streams, rivers, and lakes where, aided by bacteria can undergo a chemical transformation into methylmercury, which can be toxic.  Fish can absorb it from water as they feed on aquatic organisms.  Larger, longer living fish feed on other fish throughout their lives, thereby accummulating the highest levels of methylmercury.  Unfortunately cooking preparation and heat do not reduce mercury levels.

Which fish may contain high levels of Methylmercury?
King Mackerel, Shark, Swordfish, Tilefish

What about Tuna?
Since canned light tuna is porcessed from smaller varieties of tuna, it will have less mercury than either canned albacore (white) tuna or tuna steaks/fillets.  The FDA and EPA recommend limiting intake of both albacore tuna and tuna steaks/fillets to up to 6 ounces (one average meal) of tuna steak eaten per week.

What fish are low in mercury?
Generally smaller fish have less mercury than larger fish.  Fish with lower mercury levels include:
Catfish, cod, crab, flounder/sole, haddock, herring, lobster, ocean perch, oysters, rainbow trout, farmed salmon, wild salmon, sardines, scallops, shrimp, spiny lobster, tilapia, farmed trout.

Other sources of Omega-3 Essential Fatty Acids:
As an alternative  to eating fish, purified fish oil supplements offer omega-3 fatty acids with lower levels of contaminants.  Omega-3 enriched eggs are another source.  And micro algae based omega-3 supplement is a vegetarian alternative.

For more information:
EPA:  http://www.epa.gov/waterscience/fish/advice/
FDA:  http://www.cfsan.fda.gov/~dms/admeh3.html
           http://www.cfsan.fda.gov/seafood1.html
           http://www.cfsan.fda.gov/~frf/sea-megh.html

Thanks to Whole Foods for providing this information.  Visit their website: www.WholeFoods.com.