Seafood Surprises!

By Carol Chuang, MS, CNS, CMTA, CHC

There are many health benefits to eating fish. Not only are the omega-3 fatty acids in fish good for your heart, they also help reduce inflammation which is the cause of many degenerative diseases. Therefore, if you are health-conscious, you have probably been eating more fish and seafood on a regular basis. 

However, do you know that your heart-healthy seafood may also contain many unsavory contaminants that pose threats to your health? Nowadays, drug residues are commonly found in many imported farm-raised seafood and mercury in almost all ocean fish species. 

So what kinds of seafood are the most contaminated and what are still safe to eat?

Imported Farmed Seafood ... Questionable

Some 85% of the seafood Americans consume is imported. Much of that is farm-raised, in a practice called aquaculture, in Asia and other countries. 

The problem with farm-raised seafood is the environment in which the seafood is raised. Veterinary drugs like antibiotics, anti-fungals, anti-parasitics, pesticides, and disinfectants are frequently used to treat or prevent a wide array of production-related diseases that can spread rampantly in overcrowded conditions. In addition, many developing countries employ drugs that have been banned in the U.S.

A study from the Johns Hopkins Center for a Livable Future was published in the July 2011 issue of Environmental Science & Technology. It characterizes veterinary drug inspection policies and violations among four inspecting bodies - E.U., U.S., Canada, and Japan, using government collected data from 2000 to 2009. The following findings reveal major concerns regarding the safety of imported seafood:

• Most overseas fish farms are not inspected by U.S. officials. Moreover, the FDA (U.S. Food and Drug Administration) checks just 2 percent of imports for contaminants (including drug residues, polychlorinated biphenyls or PCBs, pesticides, and mercury), compared to 20-50% in Europe, 18% in Japan, and up to 15% in Canada.
• The FDA looks for residues from only 13 drugs, whereas Europe tests for 34 drugs. That means overseas fish farms can be using a range of drugs that the U.S. doesn't even screen for.
• Most veterinary drug violations were detected in species that are farm-raised. Shrimp and prawns top the list, followed by crab, basa (catfish), eel, tilapia, and Chilean salmon.
• Of all the countries, Vietnam had the most drug violations, followed by China, Thailand, Indonesia, Taiwan, India, and Malaysia.

Last but not least, contaminants in farmed seafood are not limited to those from developing countries. Farmed salmon from Europe has been found to contain the highest PCBs and other potentially harmful industrial pollutants. PCBs are neurotoxic, hormone-disrupting chemicals. According to one study, PCBs were found at levels seven times higher in farmed salmon than in wild ones. 

Ocean Fish ... Mercury

Mercury occurs naturally in the environment and can also be released into nature through industrial pollution. Some 2,000 tons of it enter the global environment each year from human-generated sources such as coal-burning power plants and incinerators. Deposited onto land or into water, mercury is picked up by microorganisms, which convert some of it to methyl-mercury, a highly toxic form that builds up in fish and the animals that eat them.

One of the primary ways people are exposed to mercury is by eating fish and shellfish. The other common source is from dental amalgam (mercury) fillings. Normally, the human body is capable of removing small amounts of mercury. 

However, if you are chronically exposed to heavy metals such as mercury or if your body is already loaded with toxins from drugs, alcohol, tobacco, pesticides, chemical-based household cleaners and personal health-care products, your liver and kidneys, the two major detox organs, will likely be heavily burdened. Overtime, their detox function may be compromised, leading to an accumulation of mercury and other toxins in the body.

Health effects of mercury do not show up immediately, instead, they take years to develop. They may include damage to the central nervous system, heart, and immune system, just to name a few. Developing brains of young and unborn children are particularly vulnerable, therefore, women who are pregnant and those planning to become pregnant should avoid all seafood that contain significant amounts of mercury.

Unfortunately, nearly all fish and shellfish contain some mercury. In general, larger fish that have lived longer have higher levels of mercury because they have had more time to accumulate it. 

The following list categorizes some common fish and shellfish based on their mercury content:

Highest Mercury

Escolar, mackerel (king), marlin, opah, orange roughy, shark, swordfish, tilefish (Gulf of Mexico), and tuna (Ahi, bigeye, bluefin).

High Mercury

Sea bass (Chilean), bluefish, grouper, mackerel (Gulf of Mexico, S. Atlantic, Spanish), sablefish (black cod), tuna (white albacore, yellowfin), and young yellowtail (hamachi, kanpachi).

Moderate Mercury

Bass (black, striped), carp, cod, croaker (white Pacific), halibut (Atlantic, Pacific), jacksmelt (silverside), lobster, mahi mahi, monkfish, mussels, perch (freshwater), skate, snapper, sea trout, sturgeon, tilefish (Atlantic), and tuna (chunk light, skipjack).

Low Mercury

Anchovies, butterfish, catfish, clam, crab (domestic), crawfish/crayfish, croaker (Atlantic), flounder, haddock, hake, herring, mackerel (N. Atlantic, Pacific chub, Saba), mullet, octopus, oyster, perch (ocean), plaice, pollock, salmon (Alaskan, Pacific), sardine, scallop, shad (American), shrimp, sole, squid/calamari, tilapia, trout (freshwater), whitefish, and whiting.

Things To Know When Choosing Seafood

• In the U.S., supermarkets are required to label the seafood's "country of origin" and whether it was farmed or wild-caught. However, restaurants, processed fish products and fish markets do not have to comply with this regulation.
• There is currently no U.S. government-approved "organic" seafood. When seafood is labeled "organic" on restaurant menus or in stores, it does not mean that it has been certified by the U.S. Department of Agriculture (USDA) like the meats, vegetables, fruits, and dairy.  When seafood is labeled as "organic", it is based on criteria set by private certification companies.
• Younger fish tends to accumulate less mercury. That's why the older albacore tuna caught by long-line gear in deeper waters has much higher mercury levels than the younger troll- or pole-caught albacore.
• Fish lower on the food chain, such as anchovies, herrings, and sardines, has less mercury. As larger predatory fish eats the smaller fish, contaminants are concentrated and accumulated in the body of the bigger fish.
• Avoid or limit the consumption of imported farmed seafood, especially Asian shrimp and prawns and all seafood from Vietnam, which is a big exporter of basa (catfish).
• Seafood farmed in America is much preferable to imported ones as the U.S. have stricter regulations. The relatively cleaner varieties of domestically farmed seafood include arctic char, barramundi, mussels, oysters, rainbow trout, and coho salmon. 
• The healthiest seafood is the wild, smaller fish caught from pristine waters, such as salmon, squid, anchovies, herrings, and sardines. 
• Canned wild salmon and sardines can be an economical alternative to the fresh ones. However, beware that most cans contain bisphenol A, or BPA, a toxic hormone-disrupting chemical that has been associated with cancer, insulin resistance, and birth defects. Fortunately, a number of companies including Crown Prince, Eco Fish, Oregon's Choice, Trader Joe's, Vital Choice, and Wild Planet use BPA-free liners for their canned seafood.
• Always bear in mind that almost all seafood contains some mercury. Therefore, it is wise not to over consume unless you are certain that the seafood is of the cleanest and highest quality. If you want to know whether you have accumulated any heavy metals, including mercury, in the body, the most accurate method is to get a Hair Tissue Mineral Analysis. You may contact me regarding the test as well as heavy metal removal from your body.

© Carol Chuang 2012

About the Author

Carol Chuang earned a Master of Science degree in Nutrition from Huntington College of Health Sciences. She is a Certified Nutrition Specialist from the American College of Nutrition, a Certified Health Counselor from the Institute for Integrative Nutrition, a Certified Metabolic Typing Advisor, and a Certified Functional Diagnostic Nutritionist. She is also board certified by the American Association of Drugless Practitioners.

Carol is a Professional Member of the American College of Nutrition and the Price-Pottenger Nutrition Foundation. Apart from having her private practice counseling individual clients, she writes a monthly nutrition newsletter, and conducts regular seminars on various topics of nutrition and wellness.