Both soda and diet soda are associated with the development of “Metabolic Syndrome”, which is a constellation of changes in our metabolism. It includes diabetes or pre-diabetes, as well as high blood pressure. The link to “read more” leads you to an analysis of a medical article, translated for the layperson. 

This cohort study, “Atherosclerosis Risk in Community”, abbreviated ARIC. Similar to the Framingham study, this study is following people over time to define risk factors for heart disease.A “cohort” study follows a group of people over time. Usually the people in the study have something in common: age or race or a particular disease. For example, there are cohort studies following people with HIV over time to monitor for long-term complications of both the disease and the medications. A cohort study can give us information about associations, but can not tell us anything about cause-and-effect. We can learn from cohort studies that soda is associated with the development of diabetes. We can’t say that soda causes diabetes. In order to make a strong statement about cause and effect, we would need a randomized trial where half of the participants drank soda and the other half did not drink soda.

Back to the issue at hand, in the ARIC, close to 16,000 middle-aged adults living in North Carolina, Mississippi, Maryland and Minnesota were followed, starting in the late 1980’s. Every three years, people came in for physical exams and completed food-frequency questionnaires.

For this particular slice of the ARIC study, people starting out with Metabolic Syndrome or heart disease were excluded from the analysis. That makes sense. If you are trying to figure out the risk factors for the development of Metabolic Syndrome by following people over time (prospective study), you can’t include people who already have it. You could look at the people with Metabolic Syndrome, then look back to see what they ate (retrospective study), but this study was not a retrospective study. Around 6,000 people were excluded from entering the study because they already had Metabolic Syndrome! The researchers ended up with 9,514 volunteers.

Remember what Metabolic Syndrome is. It is a cluster of diseases: 1) diabetes or pre-diabetes, 2) hypertension or pre-hypertension, 3) large waist size, 4) low HDL (HDL is good cholesterol) and 5) high triglycerides (a form of fat in the blood). Three of these five would give you a diagnosis of Metabolic Syndrome. As you see, I tend to clump Metabolic Syndrome and Diabetes together, just for the purposes of making things clearer and easier to read. Wherever you see the word “Metabolic Syndrome”, replace it with “Diabetes” or visa versa, and you will get the picture. People with Metabolic Syndrome are at high risk to die earlier from heart disease and strokes. We want to avoid Metabolic Syndrome, so let’s see if there are any hints from this study.

Over 9 years of follow-up, 40% of the 9514 volunteers developed Metabolic Syndrome. Wow! If you include the excluded people who started out with Metabolic Syndrome, 60% of those middle-aged volunteers had or ended up with Metabolic Syndrome.

Let’s look at what the people who developed Metabolic Syndrome ate, and what the others did not eat. First of all, the big meat eaters were at higher risk. Hamburgers, hot dogs and processed meats were the worst offenders. Fried foods, also bad. Cheese was good! Yes, dairy products seemed to protect against the development of Metabolic Syndrome! This is not news, or at least it should not be news. We’ve seen this in other studies, where a serving or two of dairy every day seems to protect against weight gain. Also, remember that cheese and yogurt are both an integral part of the Mediterranean diet.

The researchers were disappointed because they thought that fruits, vegetables and whole grains would be protective. There was no association one way or another. Remember though, there are plenty of other studies which show fruits, vegetables and whole grains protect against the development of diabetes and Metabolic Syndrome.

Soda gets complicated. Regular sweetened soda was associated with the development of Metabolic Syndrome. When the researchers took age and weight into account (both are risk factors for Metabolic Syndrome), soda was no longer associated with Metabolic Syndrome. We’ve seen this before also. Remember the large study in African American women. It wasn’t the soda; it was the weight gain from the soda that was associated with Metabolic Syndrome. In short, soda does not cause Metabolic Syndrome, but soda contributes to weight gain. The culprit is the weight gain, not the soda, for the development of Metabolic Syndrome.

The big surprise was the very strong association of diet soda with Metabolic Syndrome.  Even after adjusting for all potential variables, people who drank diet soda were at 34% increased risk of developing Metabolic Syndrome. We have seen this before in other studies. Diet soda is associated with the development of Metabolic Syndrome. For more information, see the article on this site entitled “Can Diet Soda Cause Diabetes?”

The advice is clear. Don’t drink soda. Drink milk. Eat cheese.

* Lutsey PL, et al. Circulation 2008;117;754-761. Dietary Intake and the Development of the Metabolic Syndrome: The Atherosclerosis Risk in Community Study

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