Many of my patients love fish as I do. It’s a good source of protein, heart-healthy omega-3 fats, and delicious! Living in an area surrounded by water, fresh fish is abundant. However, I would like to share with you an important trap of eating fish too often: mercury (Hg) levels.

So far, no cases of mercury poisoning from eating fish have been reported in the United States. However, concern about this happening has grown in the last 10 years. Although most US fish are safe to eat, many states issue health warnings that limit the consumption of certain types of fish.

As I like to tell my patients, they can safely enjoy seafood. The keywords are avoid some fish and moderation with others.

Let me explain how mercury gets into our food and who is at risk. I’ll also give you some tips on what you can do to prevent mercury from becoming a toxic problem.

How does mercury get into our environment?

Mercury enters the air by burning coal, wood, or oil. Rain and / or snow carry it to the ground, pastures, our oceans, lakes, rivers, and streams. It can also get into water from Hg-containing medical engineering waste that can be dumped into the ocean or lakes.

In water, mercury is converted to methylmercury, a highly toxic compound easily absorbed by fish through their gills or from the marine life they eat. The cooking process does not eliminate it, so every time we eat fish or shellfish we can get trace levels of mercury.

As a physician, I am concerned about the possible chronic exposure of my patients to dietary mercury that is stored in tissues. Research shows that most people are exposed to mercury from eating fish. However, the amount of Hg you eat depends on the fish you eat and where it comes from.

Who is at risk?

Although all men, women, children of all ages are at risk of mercury toxicity in the diet, women (especially pregnant women) and newborns are at the highest risk. In a recent study, it was found that 10% of American women were only one-tenth of the toxic levels of Hg.

By eating tuna even twice a week, a woman can have too high levels of mercury stored in her tissues before she becomes pregnant. Mercury can pass to the newborn and cause serious neurological damage and even death of the fetus.

Children who breastfeed can also be exposed through breast milk. Young children are also at higher risk because their brain and nervous system are not fully developed until around 11 years of age. They should not consume more than 12 ounces of low-mercury fish per week.

Do all fish have the same risk of mercury?

The short answer to this question is No. Certain lake fish such as largemouth bass and walleye, which are fish in the food chain, can have levels of mercury (and other toxins) a million times higher than those of the Water. If you like sport fishing, be aware that these types of lake fish can have a lot of toxins.

The longest answer to this question is, yes, possibly. Almost all fish and shellfish contain some mercury, and light to moderate fish consumption should not be a health concern. As I tell my patients, your risk of Hg toxicity increases with the amount and type of fish you eat regularly.

Here’s what the U.S. EPA and National Resources Defense Council (NRDC) recommend that people do to decrease exposure to mercury from eating fish:

• Avoid shark, mackerel, swordfish, tile, grouper, marlin, orange roughy, sea bass, walleye, which have the highest Hg levels.

• Limit albacore albacore tuna to 18 ounces per month; contains more Hg than light tuna.

• Limit saltwater bass, croaker, halibut, bluefin tuna, sea trout, and Maine lobster to 18 oz per month. These have moderate levels of Hg.

• Limit carp, dorado, crab, snapper, perch, cod and monkfish to 24 oz per month. These have lower levels of Hg.

• Shrimp, sardines, canned light tuna, wild Alaskan salmon, pollock, whitefish and catfish, black cod – these have the lowest levels of Hg. You can enjoy up to 12 ounces per week.

* Visit the NDRC website for a more complete list and their mercury calculator for a personal recommendation on what fish you like and how much to eat, at http://www.nrdc.org

What else can I do about exposure to mercury?

The good news is that, although Hg is stored in body tissues, it is also released. You can clear it from your body in about 6-12 months if:

• Faster: Avoid eating fish that contain mercury altogether.

• Slower: Limit your fish / shellfish intake to the lower Hg levels listed above.

Here are some other naturally-based suggestions to help you stay free of toxic levels of mercury:

• Drink adequate amounts of water each day to remove toxins from body tissues. Half of your weight should be consumed every day. If you weigh 200 pounds, drink 100 ounces of water.

• Avoid high fructose corn syrup – two recent studies suggest it may contain Hg.

• Avoid vaccines or contact lens solutions that contain thimerosal – this is a preservative derived from mercury.

• Dental amalgam fillings: If you have old mercury amalgam fillings, replace them with new tooth-colored mercury-free compounds. Your teeth will look great and you will be free from the source of mercury.

• Add some fermented foods to your diet: things like yogurt, kefir, sauerkraut, help flush toxins out of your body by creating good gut bacteria.

• Adequate amounts of vitamin C and E: help prevent the harmful effects of mercury.

• Add some natural chelators to your diet, such as garlic, selenium, coriander, and chlorella. These substances bind to toxins like mercury and remove them from the body.

• Adequate fiber intake: important for good health and to reduce levels of mercury accumulation.

• If you have old mercury thermometers, replace them with digital thermometers. Make sure to dispose of old Hg thermometers and toxic waste like old paint.

• Energy saving light bulbs, or CFLs, contain trace amounts of Hg. If they break, open windows for 15 minutes to disperse fumes. Keep children and pets away to avoid inhaling or spreading dust. DO NOT vacuum as this will scatter dust. Wear rubber gloves and cover your nose and mouth to be safe and avoid inhaling their dust. Tape or a damp cloth will help collect the particles. Used ones must also be disposed of as toxic waste.

Exposure to mercury is something that we should all avoid in our diet and in the environment as much as possible. It can have very damaging effects on our brain and kidneys and cause a whole list of symptoms and conditions including depression, fertility problems, and even Alzheimer’s disease.

However, with some common sense, following the guidelines listed here, we can still enjoy eating the seafood we love so much without worrying about toxicity!