Does Beyoncélook a little sad in her latest ad for Pepsi? New research suggests drinking sweetened beverages, especially diet versions, is linked to a greater chance of developing depression, while coffee is associated with less of a risk.

Photo by Marcel Aniceto

The Study

From 1995 to 1996, researchers followed 263,925 people between the ages of 50 and 71. Specifically, they looked at the consumption of drinks including soda, tea, fruit punch, and coffee. A decade later, the study authors checked up on participants to see who had been diagnosed with depression.

It turns out the bubbles put people in trouble: Those who drank more than four servings of soda per day were 30 percent more likely to be diagnosed with depression than people who didn’t sip the fizzy stuff at all. As for the punch, those who drank more than four cans per day were as much as 38 percent more likely to be depressed than those who didn’t drink any sweetened beverages. And forget about trying to stay slim: People who drank diet soda, diet fruit punch, or diet iced tea were the most likely to develop depression (though it’s unclear exactly how much more likely). We should note that the full text of the study isn’t available online yet, and the study authors will be presenting their findings at the American Academy of Neurology in March.

Even still, while Diet Coke fiends were spending time at the shrink, coffee addicts were doing just fine. Those who drank four cups of coffee per day were about 10 percent less likely to develop depression than people who didn’t drink any coffee.

One caveat is that the people drinking four cups of soda might have been also drinking coffee, and vice versa. Researchers didn’t give participants any rules, per say — they just asked them about their diets.

Why It Matters

This research isn’t an excuse to start guzzling coffee by the gallon — after all, it’s actually possible to have too much caffeine. Likewise, soda and other sweet stuff shouldn’t automatically end up on the “banned” list at the grocery store. But, considering that diet soda and sugary drinks might not be the healthiest choices anyway, it’s probably worth trying to replace them with water, at least a few times a day.

And don’t think just because this study looked at middle-aged folks, that people under 50 are off the hook. Weaning ourselves off the (soda and juice) bottle could be a step in the right direction, especially for folks in their 20s, since that’s when we tend to develop the health habits we’ll practice for the rest of our lives.

Can We Trust It?

Sort of. It’s not clear exactly why drinking soda is related to an increased risk of depression, or why coffee is associated with a decreased risk. These findings are supported, however, by other research that suggests coffee-drinkers are the cheeriest folks in townCoffee, caffeine, and risk of depression among women. Lucas, M., Mirzaei, F., Pan, A., et al. Department of Nutrition, Harvard School of Public Health, and Department of Medicine, Brigham and Women’s Hospital, Boston, MA. Archives of Internal Medicine 2011;171(17):1571-8.Coffee, tea and caffeine intake and the risk of severe depression in middle-aged Finnish men: the Kuopio Ischaemic Heart Disease Risk Factor Study. Ruusunen, A., Lehto, S.M., Tolmunen, T., et al. Institute of Public Health and Clinical Nutrition, Kuopio Campus, University of Eastern Finland, Kuopio, Finland. Public Health Nutrition 2010;13(8):1215-20.. As for soda and sadness, some researchers say sugar consumption may actually increase our risk for developing major depression (though that wouldn’t explain the diet soda issue)A cross-national relationship between sugar consumption and major depression? Westover, A.N., Marangell, L.B. Mood Disorders Center (MDOC), Department of Psychiatry, Baylor College of Medicine, Houston, Texas, USA. Depressoin and Anxiety 2002;16(3):118-20..

Still, it’s important to remember that this particular study doesn’t implicate that soda or fruit punch was the cause of depression. It’s also not strictly a cause-effect relationship, since it’s equally possible that participants who suffered from mental health issues were more inclined to reach for a cup of Coke or Hi-C in the first place. Likewise, coffee doesn’t necessarily make anyone smile — it’s possible that Starbucks just attracts people who aren’t as prone to depression.

It’s also worth noting that these results are all based on self-reports. So it’s possible that participants were chugging more or less than they indicated. (Hey, who wants to admit to 12 cups o’Joe during an all-nighter?)

Would you kick your soda habit if you thought it might make you happier? Let us know in the comments below or tweet the author directly at @ShanaDLebowitz.