Does splenda cause cancer?

Going bananas over artificial sweetener

Yesterday, I got an unusual text from my mom:

“In simple language, what would 16,000 ppm look like? If that was what you ate of, say, bananas” –she asked

“If you ate 1 million bananas and 16,000 of them were rotten, then you would have consumed a dose of 16,000 ppm rotten bananas” –I explained

But I had a feeling this wasn’t about bananas.

PPM or parts per million is a unit of measurement that you often see in toxicology studies. It turns out the bananas of this story were in fact sucralose.

Sucralose, also known as Splenda

Sucralose is the artificial sweetener found in Splenda. I’m not a big artificial sweetener person. I take my coffee with regular old sugar, and I might enjoy a diet coke once or twice a month. But that hasn’t stopped well-meaning acquaintances from informing me that my carbonated beverage choices are ill advised. Apparently, my mom has caught similar static over the 2 packs of Splenda she uses to sweeten her morning coffee.

This time, that static came in a Facebook post about an article from Mercola: Artificial Sweeteners Cause Cancer

This is certainly not the only headline out there making such a claim. There are a number of different artificial sweeteners, a bunch of studies testing their health effects, and even more misguided headlines misinterpreting the results. Unpacking the science behind all of them would be a full-time job, so I’m just going to dissect one to illustrate why it’s important to be skeptical of alarmist headlines about food safety.

The latest study testing if Splenda causes cancer

The first study Dr. Mercola (doctor of osteopathy, not medical doctor) cites was published in the International Journal of Occupational and Environmental Health in 2016. This journal is not of especially high impact to the scientific community, but it is a legitimate journal.

900 mice were exposed to sucralose starting from the time they were 12 days old (through their mom’s feed) throughout their entire lives. They were given different doses of sucralose at concentrations of either 0, 500, 2000, 8000, or 16000 parts per million.

So how much sucralose is 500 of 16,000 ppm? To make the conversion simple, I’ll use the WHO conversion table, which states that for typical mouse feeding studies (with mice weighing ~0.02 kg and eating ~3 g per day), 1 ppm is equivalent to 0.15 mg/kg by weight per day.

The mice fed in this study varied in weight from ~.004 kg for pups to .025 – .05 kg for adults, and the adult mice ate ~3-6 grams. So the WHO conversion isn’t perfect, but it’s in the right ballpark.

So assuming 1 ppm is equal to .15 mg/kg/day, that means that the concentrations of sucralose used in the study (500, 2000, 8000, and 16000 ppm) convert to 75, 300, 1200, and 2400 mg/kg/day.

You’d have to eat almost 500 packs of Splenda per day

The FDA recommends consuming less than 5 mg/kg of sucralose per day, so even at the lowest doses, the mice were exposed to 15 times more than the FDA recommends every single day for their entire lives. To put that amount into perspective, 5 mg/kg/day for a 150 pound person equates to 28 packets of Splenda.

So for the lowest dose in mice (75/mg/kg/day) the equivalent for an average human would be about 420 packs of Splenda per day every day for their entire life. Even if humans are an order of magnitude more sensitive to sucralose than mice, that’s well over the recommended dose per day, and way more than any human would ever consume.

The results linking Splenda to cancer are not very convincing

So what happened to the sucralose-stuffed mice? The researchers mainly looked at mortality and tumor development. I’ve highlighted what I found to be the most convincing results here.

This graph is nearly impossible to interpret, because all of the lines look the same, but here is what the researchers conclude about the data:

“Compared to controls, a significant dose-related decrease (p ≤ 0.02) in survival was observed among treated male mice and, in particular, in males treated at 16,000 (p ≤ 0.009) and 2,000 ppm (p ≤ 0.04). A non-significant decrease in survival was observed in females treated at 2,000 ppm.”

In short, male mice fed 2,000 or 16,000 ppm of sucralose died a bit sooner.

The significant data and controls on tumor development are highlighted in this table. (Significant meaning differences between mice treated with sucralose and controls were unlikely to have occurred at random)

For male mice only, those exposed to the highest doses were somewhat more likely to develop malignant tumors (red boxes). Male mice were also more likely to develop Leukaemias at high doses (green boxes).

The authors conclude that sucralose is “not bioinnert” as some previous studies have claimed. At high enough doses over a long enough period of time, sucralose likely has an effect, at least for male mice.

The study DOES NOT conclude that a Splenda in your morning coffee or the occasional diet coke will cause cancer. The dose makes the poison, and for sucralose, that dose is very high.

Issues with the study design

What’s more, the treatment groups in this study were either sucralose or no sucralose. When you’re deciding whether or not to put that Splenda in your morning coffee, you’re probably choosing between between an artificial sweetener or plain old sugar. We know that consuming too much sugar is bad for you, and the deadly dose for sugar is well below 400 packs a day. And that coffee you’re sweetening –also a known carcinogen, if you drink enough of it.

But I’m not writing this to make you scared of your morning coffee. I’m also not writing this to convince you not to be skeptical about whether or not the things you consume are safe. I’m writing this to encourage you to be skeptical of articles like Dr. Mercola’s that make radical health and safety claims.

Do what my mom did. Instead of reading the article, swearing off Splenda, and sharing it with all your diet coke loving friends, read the article and ask yourself, how much is 16000 parts per million? Was this study conducted in humans? If it came out two years ago, why didn’t you see headlines about Splenda causing cancer in major newspapers? And importantly, what does Dr. Mercola stand to gain financially from writing this article?

Right at the top of his website you’ll find a link to a staggering line of health food products and supplements. No doubt, the antidote to whatever benign household product he’s trying to convince you is poison.

So, does splenda cause cancer? Maybe if you’re a male mouse. Maybe if you eat 500 packs a day. But since you’re not a mouse, and you would likely never eat more than 5 packs a day, I’ll bet you’ve got bigger things to worry about.