Thursday, May 27, 2010

Too Much of a Good Thing?

The May 20, 2010 issue of the New England Journal of Medicine contains this interesting correspondence: Myxedema Coma Inducted by Ingestion of Raw Bok Choy. The letter was submitted by Michael Chu, MD and Terry F. Seltzer, MD, both of the New York University School of Medicine.

In summary, an 88-year old Chinese woman with diabetes was brought to the emergency room because she was lethargic and unable to walk for the past 3 days. The family reported she was eating 1 to 1.5 kilograms of raw bok choy daily for several months in the belief it would help control her diabetes. She had no thyroid disease.

In the emergency room, they found that her legs and eyelids were swollen and her tongue enlarged. And she was comatose. They did a bunch of labs on her and found that her thyroid tests were abnormal. She survived after intense medical therapy.

Drs. Chu and Seltzer discuss that cabbage contains substances called glucosinolates. The glucosinolates breakdown into compounds that have been implicated for their inhibitory effects on the thyroid. To complicate matters, when eaten raw, members of the cabbage family release another compound, myrosinase, that accelerates the breakdown of the glucosinolates. However, cooking the veg seems to deactivates the myrosinase.

What struck me as curious was the amount of raw bok choy this lady was eating daily---1 to 1.5 kilograms (2.2 to 3.3 pounds). Okay, okay, you say that no one would eat 2-3 pounds of raw bok choy daily. That would be an insane amount that no one could possibly keep up for more than a few days.

Or could they?

1 kilogram of raw bok choy per the USDA Nutrient Database has 20. 3 net carbs. (NOTE: bok choy is listed as Chinese cabbage pe tsai on the Database). So if an Atkineer aims to get at least one half---or more!-- of their daily net carbs from veggies alone and if they do as this unfortunate lady did, then perhaps the New England Journal of Medicine will receive another letter reporting myxedema coma and severe hypothyroidism in a person who went overboard on their veggie choice.

I think there were two things in play here: 1. The idea that “because it’s a vegetable, it can’t possibly be bad for you” and 2. The idea of “if alittle is good, then a lot must be better.” As this unfortunate case shows, vegetables should not be taken for granted and that moderation---even with vegetables--- is the key to health.

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