Tuesday, July 13, 2004

"Soda causes diabetes! News at eleven."

Be wary of statistics. For a long while now, I have noted with amusement various statistics meant to frighten, cajole and persuade. At first glance, these statistics are frightening, but a dose of cynicism and a little bit of thinking will go a long way:
Sensationalism runs amok at eDiets.com: "Now here's some scary news: Harvard School of Public Health research indicates women who drank at least one sugar-sweetened soda a day were 85 percent more likely to develop type 2 diabetes than those who drank less!"

Well, yes, I don't doubt the veracity of the study. Upon cursory glance, it seems quite legitimate – isn't heavy sugar consumption linked to diabetes? Yes and no. People who consume a lot of sugar are generally overweight, and obesity is definitely a cause of diabetes. But simply consuming a lot of sugar will not, in itself, cause diabetes.

Then, it is very likely that "one sugar-sweetened soda a day" will not cause an 85 percent jump in the diabetes rate. One sugar-sweetened soda a day, coupled with an unhealthy diet and lack of exercise, will. This Harvard study found a correlation, not a causation.

Not convinced? Look at this snippet from an AP article:

"According to [the] study, the women most prone to gaining weight had increased their consumption of sugary soft drinks from less than one a week to more than one a day. On average, those women gained nine-10 pounds in a four-year period. But women who cut their intake of soft drinks gained an average of three pounds or less."

Honestly, I am not entirely sure what this means. Did the study organizers pick the women most prone to gaining weight and ask them to increase their soda consumption more than seven-fold? In any case, it is clear that there is a very fundamental question here: What caused the increase in diabetes – the increase in sugar consumption or the increase in weight?

In a nod to fair and balanced reporting, the AP quoted a press release from the National Soft Drink Association that responded to the study. The soft drink makers called the study "unconvincing and inconclusive" because it raises questions over "factors that could create inaccuracies." The article stopped there, but a quick skim of the press release provides the needed details:

"It is unknown whether or not this study adjusted for all of the above risk factors for type 2 diabetes or for other risk factors sometimes referred to in the medical literature such as high salt intake, high blood pressure, alcohol intake and high fat intake. If this study were adjusted for all of these confounding factors, it is doubtful it would show any risk for developing type 2 diabetes from soft drink consumption," said Dr. Richard Adamson, vice president for scientific and technical affairs for NSDA.

The moral of the story? It's easy to fall victim to scary statistics. Respond with your mind rather than your fears. Always look at both sides of an issue. And don't believe everything you read.