Don't, Don't, Don't...

After I graduated from university, I spent a year living in Japan, teaching English.  Dan Strack, a fellow English teacher, hilariously captured in song what it's like to be a Westerner in Japan. Needless to say, any Westerner living in Japan who wants to try to avoid embarrassment has to learn some new rules.  His song "Don't" (from his album The Gaijin Years) offers a few tips on doing this.  Here are the opening lyrics:

Living in Japan is like crossing a minefield:
embarrassing explosions can happen every day.
Even if you understood everything going on around you,
chances are you still wouldn't understand what to do or say...
I hate to dwell on negatives or be too pessimistic, 
but here are a few rules that have been useful to me.

Don't, don't, don't...
Don't wear your shoes on tatatmi
Don't try to guess what's in that pastry...
Don't buy the salt-flavored toothpaste
Don't take part in a late-night downtown drag-race

The "don'ts" continue for several verses and several minutes, and then the song (almost) concludes:

Don't use umbrellas with typhoon winds blowing
Don't you wonder how long this song can keep going?
You may think I'm just exaggerating, so I'll sum it all up.
There's just one thing to keep in mind when push comes to shove
Remember...all...of the above

Being pregnant seems to come with a similarly endless list of don'ts.  No alcohol, caffeine, soft cheeses, over-the-counter meds, hot tub use, sushi, etc.  Since this is turning into a Japan-themed post, let's look at the evidence regarding eating sushi (and fish more generally) during pregnancy. I admit to immediately being skeptical of all the warnings against pregnant women eating sushi and cooked fish - the majority of Japanese women still list sushi as their favorite food (for Japanese men, it's steak), many eat it daily, and they don't seem to slack off on their sushi habit when pregnant.  And when they're not eating sushi, they're often eating grilled fish, or some kind of soup or sauce made from fish stock.  Yet neither they nor their babies have the sorts of health problems one would expect given the dire warnings we hear from US health agencies.  So what's going on?

Note: Before I get started, I should stress that I'm not a doctor and this is not medical advice.  

I'm just an educated, thinking person sorting through the publicly available evidence
and hysteria (ha!) regarding this issue. 

There are two main concerns with eating raw sushi during pregnancy: the risks of eating uncooked meat and the mercury content of fish. Let's look at each supposed risk in turn. Uncooked meat is more likely to harbor parasites, and eating uncooked meat is more likely to cause food-borne illnesses.  Some food-borne illnesses can be life-threatening to a fetus, even if they would just be a rather disgusting inconvenience to a healthy adult.  Raw sushi served in the States, though not cooked to kill parasites and other icky stuff, is flash frozen—this basically provides the same protection from parasites and microoganisms as cooking does.  A 1991 National Academy of Sciences Institute of Medicine study seems to confirm that food-borne illnesses from sushi are not a serious concern; most seafood-associated illnesses come from raw mollusks.  If you remove those from the statistical pool, your risk of falling ill from eating seafood is 1 in 2 million servings.  By comparison, the risk from eating cooked chicken is 1 in 25,000.  Given my own food poisoning experiences—all 3 caused by chicken and none caused by anything else, and this despite the fact that I regularly eat sushi, medium-rare steaks, and pork that isn't well-done—this seems about right.  If we consider only this risk, it seems you'd be wiser to swear off chicken and eat sushi your whole pregnancy. (This isn't completely fair to chicken, though, since salmonella is typically less dangerous to the fetus than some other common parasites and bacteria.)  Avoiding raw shellfish does seem like a good idea, though. 

What about the mercury risk?  Mercury poisoning can cause severe neurological damage, damage to peripheral vision, and worse, and the effects are typically more serious for the fetus than for the mom ingesting the mercury-laden food.  Who would want to risk this?  No one would, of course, but there is no reason to think that anyone is taking any risk from eating fish—even from eating fish on a regular basis.  Some of the scary literature out there is based on the fact that EPA's "reference dose" for ingestion of mercury is set many, many times below the level of mercury that has been shown to cause any harm.  Almost three-quarters of Japanese women of childbearing age have mercury levels above the EPA reference dose.  Similary, "over-achieving Chinese children in Hong Kong, whose blood-mercury levels are between 10 and 18 times as high as their counterparts in the United States" are clearly not suffering any ill-effects from their fish consumption.  The only clinical cases documenting mercury poisoning from fish involve people eating fish from waters that were the direct dumping grounds for industrial waste (the infamous Minamata Bay and Niigata mercury poisonings).

Based on the very low incidence of food-borne illnesses from eating fish and the fact that there is no reason to think that the trace amounts of mercury in fish will lead to any health effects—especially among Westerners who simply do not eat much fish, even if they have a serious sushi habit—I don't see any reason to avoid sushi when pregnant.  Given the nutritional value of fish, sushi  will probably only be beneficial to your health and that of your developing baby.

For my next post: the risks of ingesting alcohol when pregnant.

Sources
http://www.mercuryfacts.org/faqMercury.cfm

http://www.nytimes.com/2007/07/15/opinion/15shaw.html

Read more at http://www.babymed.com/food-and-nutrition/how-safe-it-eat-sushi-or-raw-fish-during-pregnancy?ktrack=kcplink