More on Sugary Beverages and Your Health

Last week we shared an overview of current research on sugar-sweetened beverages. These beverages include soft drinks such as sodas or colas, sweetened fruit drinks (not those that are 100% juice), and energy and vitamin water drinks. This week I have what is known as a meta-analysis to share with you.

Unlike an overview, which details the results of many studies on an individual, study-by-study basis, a meta-analysis combines the results and data of several studies to yield results as if they were all one study. (Those of you with a science background will recognize that this explanation is rather simplified.) The strength of a meta-analysis lies in the fact of its aggregate size: the larger and longer a study is, the more reliable are its results. The drawback, of course, is that this is a grouping of studies, all performed by different people with different standards and methods.

Today's meta-analysis was reported in Diabetes Care (2010;33(11):2477-2483) and groups together 11 prospective studies that together included over 310,000 people. Remember that "prospective" means that people were recruited to participate and then their health was followed after they enrolled in the study - as opposed to retrospective studies, in which those who participate in the study are asked to remember and report on something that happened in the past. Retrospective studies are much cheaper to perform than prospective studies, as they require much less time to perform. However, they are also less reliable because they are based on the assumption that people remember things accurately and report them accurately.

The researchers doing the meta-analysis standardized the serving size of the sugar-sweetened beverage consumption measured in each of the eleven studies. Then they were able to stratify the various levels of intake into groups: from none or less than 1 serving per month up to more than 1 serving per day. The amount of soft drinks drunk by individuals who developed type 2 diabetes or metabolic syndrome was then compared to the amount drunk by those who did not develop type 2 diabetes or metabolic syndrome.

The scientists found that even when they took into account other variables such as Body Mass Index or individual caloric intake, those who drank at least one 12-ounce serving of a sugar-sweetened beverage per day were 20% more likely to develop metabolic syndrome and 26% more likely to develop type 2 diabetes than those who drank less than 1 serving per month.

In their report, the researchers note that these results can't be attributed to soda-drinking people being overweight because of the extra calories they are consuming. Indeed, the sugars used in these drinks are thought to contribute to the risk of metabolic syndrome and type 2 diabetes because they promote fat deposits around the internal organs (contributing to poor cholesterol scores) and contribute to a higher glycemic load, which leads to insulin resistance, one of the symptoms of metabolic syndrome.

What this means for you

It's really not looking good for drinking sugar-sweetened beverages regularly. If you're drinking the stuff daily, you'll be doing yourself a favor to at the very least switch to the diet version of your soft drink of choice. Better yet, switch to unsweetened coffee or tea. Best? Water.