There’s a new study from France on artificial sweeteners and cancer, and predictably, the media has taken it and run with headlines like, ‘Artificial Sweeteners are Associated with Increased Cancer Risk, Finds Large-Scale Cohort Study’!
I’ve been fielding questions around artificial sweeteners for years, and reading the comments in response to this study on social media, it looks like people are still petrified of consuming them, because CHEMICALS. OMG! Artificial sweeteners are MADE IN A LAB!!! SCARY!
It’s important to note that no matter what you’ve heard from randoms online, artificial sweeteners have never proven to be unsafe, or to increase the risk for any disease. I wrote all about that here in my post about diet soda.
And it has to said, that EVERYTHING is made up of chemicals. Just because something was developed by humans doesn’t mean that it’s unsafe to eat. I see the exact same fear mongering around GMOs, and it’s not based in any scientific evidence whatsoever.
But what’s the deal with this study (and these headlines)? Do artificial sweeteners really increase our risk for cancer?
And what do we need to look for when we see headlines like these?
Let’s dive into this.
Sweetener and cancer risk: the study.
Researchers wanted to do a human study on the effects of artificial sweeteners, as research on these ingredients has been done mostly in animals and cells. Since there was an available cohort of people in the Nutrinet-Sante study, it was convenient for them to use that group.
Nutrient-Sante, hmmm, where have I heard that name before?
Oh yeah! I cited research from it in my organic vs conventional food piece. Turns out, that study had similar results – people who ate more organic food seemed to have a lower risk for cancer. At least, that’s what the media was saying. My post found something different, but this goes to show you that there’s a certain pattern of poor reporting that happens with nutrition studies. It’s not just once or twice, either…it’s all the time.
Be aware that headlines about nutrition studies and disease risk are rarely what they seem.
Back to this sweetener study.
The study was observational, meaning that researchers followed a group of over 100,000 people over an average of 8 years, in order to see if there were any associations between two particular things – in this case, consumption of artificial sweeteners and cancer.
Researchers had participants fill out 24-hour food recall surveys over the duration of the study, then followed up with them to see how many of them had gotten cancer. Researchers categorized participants into one of three groups according to their consumption level of sweeteners: non-consumers, lower-consumers, and higher-consumers.
The scientists analyzed consumption of total artificial sweeteners in the last two groups, as well as individual sweetener types. The most commonly consumed sweeteners were aspartame, acesulfame-K, and Sucralose, aka Splenda.
Then, they drew their conclusions: people who consumed the most sweeteners, seemed to get cancer more often than those who didn’t consume them at all.
To be specific, the people who consumed the most aspartame and acesulfame-K were also the ones who got more cancer.
This is the narrative that the media grabbed on to. It definitely makes for some great clickbait, and it also feeds into the public’s fear of sweeteners and ‘confirms’ their suspicions (even if those ‘suspicions’ have never been proven by any science).
A lot of the comments I’ve seen online were along the lines of, ‘we’ve known this ALL ALONG!’
‘I’ve ALWAYS known never to eat anything that’s made in a lab!’
And my personal favourite, ‘Dietitians have been saying (that sweeteners are harmful) for AGES! They’re even worse than normal sugar!
Sorry, I couldn’t hold my fire on that one…see the screenshot below.
So about these results: are they the whole story?
What isn’t being accounted for here?
Turns out, quite a bit.
Let’s talk about the cohort, a large percentage of which were women – almost 79%. This is called a selection bias, and it means that an entire part of the population aka men – was under-represented. Results, therefore, may not be applicable to the general population. This is an issue when you’re telling people that X gives everyone a scary disease.
Second, the participants’ intake was self-reported. This is never a great way of getting information for a study (although very common for nutrition studies, since you can’t hold people in a lab for 8 years to control what they’re fed). In fact, 15% of the participants were rejected because they underreported what they were eating. But that’s not even the worst part.
Sweetener intake wasn’t accounted for in exact measures. Nobody consumes sweetener on its own, so researchers had to pull details from the products that participants had in their food records.
For example, the main source of artificial sweeteners for people in this study was soft drinks. Another one was yogurt and cottage cheese.
How accurate is data that’s collected in this way? It’s definitely not ideal and leaves a lot of room for error.
Food records were done every 6 months or so, which is fairly frequent – I’ve seen plenty of studies that only do a single collection of consumption data and then draw conclusions from that. Each person’s sweetener consumption was averaged over those 8 years. But still, how many women changed their diets during that time? How does that factor in?
Third, there were some serious confounders that existed, even though as with most studies, the researchers tried to control for them. The people who consumed the most sweeteners were women who smoked and had diabetes, which in themselves place individuals at increased risk for health issues.
The most common cancers that researchers found were breast cancer and obesity-related cancers. This is interesting, since the majority of the participants were women (and yes, men get breast cancer too, but it’s less prevalent in males), and although researchers controlled for weight and other confounders, there’s no way that they could control for them perfectly.
We know that women, in particular women who are deemed to be overweight, seem to have a higher risk for cancers in the first place. Did this play a part?
Do people who consume more sweeteners also consume more ultra-processed foods?
Are they more sedentary?
How many of those diagnoses over the span of this studies had nothing to do with sweeteners, and instead were the result of other risk factors?
We can’t know for sure, but the influence of confounders – even with controls – are always something we need to consider.
Finally, we learned from this study that a high consumption of artificial sweeteners appeared to result in a 13% higher risk for cancer in study participants. That sounds scary, right? But wait! that’s relative risk, not absolute risk.
I’ll put it this way:
Out of 1000 participants who never consumed sweeteners, 31 cases of cancer were diagnosed over those 8 years.
In absolute risk, if those same1000 participants had consumed higher amounts of sweeteners, 35 would be diagnosed with cancer.
That’s not a huge number, and there’s also a margin of error as well.
(I write more about relative vs absolute risk here, in my post A Primer on the Basics: How to Read Nutrition Research)
The study authors admit that all of the above factors may have skewed the results, and they also clearly state that their research does not show causation between artificial sweeteners and cancer. DING DING DING!!
You’ve heard it before: correlation does not equal causation.
Just because two things appear to be linked, doesn’t mean they are. Of course, there’s always a chance that they ARE linked, too. We need to be fair about this either way.
This study is another great example of how difficult it is to do nutrition research, and how the media loves some good clickbait. I blame the media for the confusion more than I blame the study authors, who were upfront about the study’s limitations, and who never said there was evidence that establishes causation between sweeteners and cancer.
My recommendations around sweeteners haven’t changed, and they won’t change because of this study.
Eat whatever sweetener you like – sugar, agave, Splenda, stevia, whatever. But use as little as possible – not because they’re ‘toxic’ and cause all sorts of scary diseases, but because we eat enough sweet as it is, and by cutting it down, we can teach our bodies to expect less sweet overall.