Confounders, Biases, and the Sweetener Science

One of the old dictums of journalism, old even when I was young, is that dog biting man is not news, but man biting dog is. The former is what we expect to happen. The latter is unusual, the opposite of our expectation and so, in a word, newsworthy.

n the personal health sphere, a study that shows you can lose or maintain your weight using artificial, non-caloric sweeteners is also not news. That’s why these sweeteners exist, isn’t it, as a means of weight control? But if researchers report the opposite, that these non-caloric sweeteners actually make you fatter (or cause any disease at all), that’s going to end up in the news. And it has.

Yet another seminal epidemiologic study has linked artificial sweeteners to fat accumulation, leaving us, once again, with the kind of conflict that plagues virtually all of nutrition science. This conflict is not only between what’s news and what’s not, but what epidemiologists would like to believe is true — that these diet-disease correlations imply causality — and what the experimental tests repeatedly suggest is not.

As even the World Health Organization (WHO) acknowledges, artificial (i.e., noncaloric) sweeteners do indeed seem to help with weight loss in clinical trials. The caveat is those trials tend only to last a few months. What about longer-term use? We don’t use these sweeteners for just a few months. We use them throughout our lives. That’s where the epidemiology comes in. When people who use these sweeteners for years to decades are compared to people who don’t, the ones who come out the fatter are the users, suggesting that sweeteners do more harm than good. It’s this kind of long-term comparison that’s the essence of the new report. And, indeed, even the authors suggest that their findings are sufficiently worrisome that we should rethink national recommendations to replace added sugar with artificial sweeteners. In a word, seriously?

[Let me warn you ahead of time, this is a long one. ~ Beege]