Diet Soda: Silent, But Maybe Not so Lethal

| Thu Mar. 1, 2012 9:58 PM EST

My colleague Tom Philpott reports on a study suggesting that diet soda is bad for you:

Known as the Northern Manhattan Study and housed at Columbia University, the project enrolled thousands of people from the community and subjected them to medical testing while recording their food consumption habits.

Among its results, a surprising one has emerged []: People who drink at least one diet soda a day are 43 percent more likely to experience a "vascular event"—i.e., strokes and heart attacks—than people who drink none....Crucially, this study accounted for factors like weight, diabetes, high blood pressure, and intake of calories, cholesterol, and sodium, study author and University of Miami epidemiologist Hannah Gardener told me in a phone conversation. In other words, nonoverweight diet soda drinkers showed significantly more risk of heart attack than nonoverweight people who don't drink diet soda.

I ran across this study a while ago, and I'd urge caution for a couple for reasons. First, the sample size was pretty small: only 116 participants drank diet soda daily. Second, there was no dose-response finding. If you drink six diet sodas per week, you're fine. If you drink seven or more, you need to get measured for a coffin. This suggests fairly strongly that something else might be going on. For example, the results might be driven by a small number of very heavy diet soda drinkers, or it might be that people who drink diet soda daily are making up for other parts of their diet that are the actual root of the problem. Even Gardener is wary of drawing any firm conclusions:

Gardener acknowledged some limitations of the diet soda study, including the use of self-reported dietary data at a single time point, and concluded that the findings are "too preliminary to suggest any dietary advice."

"If and only if the results are confirmed can we suggest that diet soda may not be an optimal substitute for sugar-sweetened beverages, which have been shown to have various health consequences," she said.

In any case, I drink three or four diet sodas a week, so I guess I'm good. Aside from that, I find that water is a pretty good hydration tool. Cheap, too.

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