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Society has a remarkable love-hate relationship with artificial sweeteners. Originally marketed as a miracle—enjoy your favorite foods without the nasty sugar!—they’re now the target of wellness influencers across the internet. It’s not just health “coaches” and homesteading moms leading the charge: This year’s deeply problematic Make America Healthy Again report singles out artificial sweeteners as one of the major issues with American food.
Recent headlines seem to support this belief. According to dozens of articles, artificial sweeteners are harming our cognitive health. The news sounds scary for those of us who enjoy the occasional artificially sweetened soda, let alone the (many) people who consider a can of Diet Coke to be a personal accessory. What if these chemicals really are destroying our neurons?
Fortunately for those of you who, like me, enjoy a regular can of Pepsi Zero Sugar, the data is extremely weak. Artificial sweeteners are probably fine for your brain.
These alarmist headlines are based on a new study that analyzes a medium-sized cohort of Brazilian public servants. People were asked once about the foods that they ate and then followed up with for about a decade, and then the authors looked at the association between various sweeteners and later cognitive health. Basically, they looked to see if the people who ate more sweeteners had worse brain function over time.
The results were pretty unimpressive. In the entire sample of people, there was no significant relationship between the sweeteners in the study and cognitive health. For people under 60, there were some declines in memory associated with more sweeteners, but no such findings for people over 60. There were also very mixed results: Two measures of cognitive decline showed some associations with sweeteners, but another test had different results.
In addition, the reductions in cognitive health for the under-60 group were mostly very small. People who ate the most sweeteners—which in this case was up to 200 times as much as people who ate the least—lost about half a point more on a 30-point scale over the decade of the study. That’s not nothing, but with such a huge difference in intake, it’s remarkable that the difference in cognitive issues was so small. (Would you rather: Give up Diet Coke, or forget, say, your college roommate’s stepdad’s name 10 years down the line?)
This study was also observational, which regular readers know introduces all sorts of issues. In this case, that means that the authors were just testing correlations rather than looking at whether one thing caused another. There are all sorts of issues that could have messed up the results that an observational study can’t control for. It’s not easy to remember what you ate for lunch last Wednesday, and there’s really only so much you can do with an analysis looking at what foods people say they eat. People are notoriously terrible at answering this sort of questionnaire, and often get large parts of them wrong.
It’s also very hard to take a food-frequency questionnaire and identify specific additives in people’s diets. You have to make some sort of estimate based on what you think the products that they eat are likely to contain, but those guesses are always going to have holes. (Brazilian commenters online have noted that tagatose, one of the sweeteners included in the study, is actually a type of sugar and is also not used at all in Brazil.)
Perhaps most importantly, the idea that this blend of sweeteners is harming cognitive health is hard to understand. The list of sweeteners that the study analyzed together includes vastly different chemicals, all of which break down into different things inside our body. These likely wouldn’t all impact cognitive health in the same way.
It’s easy to see why these headlines draw us in: There’s so much conflicting information out there about what’s “healthy” and what isn’t. Nutritional epidemiology has had some very interesting findings, but there is very little that this sort of study can really tell us about what you should have in your diet. If I’m being generous, it’s an interesting prompt for further research. More realistically, it’s just a distraction.
We already knew that people who drink and eat artificial sweeteners are generally worse off than people who don’t. That’s no surprise—the main reason we use these additives is to lose weight. Generally, people who want to lose weight are a bit less healthy than people who don’t.
My verdict: There’s no good evidence that these sweeteners are harming your brain. My advice is always to drink water if you’re really worried, but this new data certainly won’t stop me from popping open a can of Pepsi Max.
