Easy on the Sushi

If you're a fan of sushi, it's worth noting that some types of fish tend to contain more mercury than others; by choosing wisely, you can minimize your risk of experiencing mercury toxicity.

In a relatively unpolluted setting, raw fish is an excellent food choice for most people - few other foods provide the same abundance of healthy protein, healthy fatty acids, and micronutrients.

Unfortunately, many decades of global industrialization have led to high levels of environmental pollutants in just about every corner of our world, including deposits of mercury in fish.

In January of 2008, The New York Times published an article that reported the findings of random tests performed on sushi from several Manhattan stores and restaurants. Their investigative study found that 25 percent of the sushi tested had dangerously high levels of mercury, high enough to warrant confiscation by the FDA. Store and restaurant owners were just as surprised by the results as their patrons.

Why is it important to avoid mercury toxicity?

Mercury is highly toxic to your nervous system. Mercury poisoning may lead to:

• Memory loss

• Tremors

• Loss of vision

• Nerve dysfunction in your extremities, most commonly presenting as numbness of your fingers and toes

• Problems with fertility

Mercury toxicity is especially dangerous for pregnant women and young children because exposure to mercury while in the womb and/or during the first few years of life may cause:

• Blindness and deafness

• Mental retardation

• Cerebral palsy

• Learning disabilities

• Retarded physical development

Some points worth noting from The New York Times article:

1. Generally, the more expensive the variety of tuna, the higher its potential mercury content, as premium varieties of tuna tend to come from larger species that eat a lot of fish and accumulate mercury with each fish eaten.

2. Bluefin tuna tends to have higher levels of mercury than yellowfin or albacore tuna.

3. Cooking fish doesn't alter its mercury content.

4. In order to reduce risk of mercury toxicity while consuming fish for its health-promoting nutrients, it's best to eat smaller fish that are lower in the food chain.

As mentioned above, larger fish act as predators to a larger quantity and greater variety of smaller fish, so larger fish tend to have the highest concentrations of mercury in their flesh. Unfortunately, many of the fish that are selected for sushi and sashimi are the larger predators.

What follows are two lists - compiled by the Natural Resources Defense Council - that highlight sushi choices that tend to contain high levels of mercury and those that tend to contain low levels of mercury.

Sushi that Tend to be High in Mercury (More than 0.3 parts per million)

Ahi (yellowfin tuna)
Aji (horse mackerel) *
Buri (adult yellowtail) *
Hamachi (young yellowtail) *
Inada (very young yellowtail) *
Katsuo (bonito) *
Kajiki (swordfish)
Maguro (bigeye, bluefin or yellowfin tuna)
Makjiki (blue marlin)
Meji (young bigeye, bluefin or yellowfin tuna)
Saba (mackerel)
Sawara (Spanish mackerel)
Seigo (young sea bass)
Shiro (albacore tuna)
Suzuki (sea bass)
Toro (bigeye, bluefin or yellowfin tuna)

Sushi that Tend to be Low in Mercury (Less than 0.29 parts per million)

Akagai (ark shell) *
Anago (conger eel) *
Aoyagi (round clam)
Awabi (abalone) *
Ayu (sweet fish)
Ebi (shrimp)
Hamaguri (clam)
Hamo (pike conger; sea eel) *
Hatahata (sand fish)
Himo (ark shell) *
Hokkigai (surf clam)
Hotategai (scallop)
Ika (squid)
Ikura (salmon roe)
Kaibashira (shellfish)
Kani (crab)
Karei (flat fish)
Kohada (gizzard shad)
Masago (smelt egg)
Masu (trout)
Mirugai (surf clam)
Sake (salmon)
Sayori (halfbeak) *
Shako (mantis shrimp)
Tai (sea bream) *
Tairagai (razor-shell clam) *
Tako (octopus)
Tobikko (flying fish egg)
Torigai (cockle)
Tsubugai (shellfish)
Unagi (fresh water eel) *
Uni (sea urchin roe)

* Mercury levels in these fish were not available - their levels were extrapolated from those of fish with similar feeding patterns.

The data for these NRDC lists was compiled from the Food and Drug Administration, which tests fish for mercury, and the Environmental Protection Agency, which determines mercury levels that it considers safe for women of childbearing age.

Again, please note that cooking fish doesn't change its mercury content, so all of this information is relevant to meals that include cooked fish.

If you eat sushi and/or sashimi once in a while, you likely have nothing to worry about. If you eat sushi, sashimi, or cooked fish on a daily basis, it's definitely in your best interest to choose fish from the low mercury list and to be on alert for symptoms of mercury toxicity.

Women who are pregnant or planning to become pregnant should take special care not to eat fish from the high mercury list.

Generally, the following fish tend to be low in mercury and safe choices for adults and kids alike:

• Wild pacific salmon
• Anchovies
• Sardines
• Arctic char

Please consider sharing this post with family and friends who regularly eat seafood. Thank you.