In a classic example of mixing up cause and effect, Harvard University researchers exonerated diet sodas and other artificially-sweetened beverages from previous studies linking their consumption to diabetes. Published in The American Journal of Clinical Nutrition, the new study analyzed data from over 40,000 men who were followed between 1986 and 2006 and found that those who drank about one serving of sugar-sweetened beverages daily were 16 percent more likely to be diagnosed with diabetes compared to men who avoided these refreshments. The authors then went on to find that even men who drank diet sodas were more likely to get diabetes, but after they controlled for weight, blood pressure and cholesterol, the association disappeared.
This proves the point that prior studies linking diet soda consumption to diabetes were flawed due to confounding variables arising from a poorly designed study. “People who are at risk for diabetes or obesity…those may be the people who are more likely to choose artificial sweeteners because they may be more likely to be dieting,” Dr. Rebecca Brown, an endocrinologist at the National Institutes of Health, told Reuters Health.
“This is such a great example of confusing cause and effect. It’s akin to saying ‘playing basketball makes you tall’ because height and basketball are correlated. Of course, the real answer is that taller people play basketball,” explains ACSH's Dr. Josh Bloom.