Corn Syrup Causes Cancer…In Mice

When extrapolating from rodent models doesn’t quite work

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Pictured: Cancer, probably

Sugar has been the evil for decades. I remember chowing down on sugar-free chocolate as a child, because we were all convinced that taking a single ingredient out of a calorie-heavy concoction was the key to a healthful life. Award-winning documentaries have been spread around the globe for years, telling us that the endless abyss is coming and it looks a lot like candy corn.

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Pictured: Endless abyss

So it was no surprise to anyone when headlines emerged recently screaming at us all that sugar, or specifically that truly horrendous high-fructose corn syrup, was giving us cancer. Not content to make us fat and diabetic, this demon in sweetener form is somehow causing tumors too.

It put me right off my M&M/fanta breakfast combo.

But, fortunately for those of us with a sweet tooth, there’s good news. While it’s definitely true that eating too much sugar is bad for you in a variety of ways, it’s currently unlikely that you have to worry about cancer because of your daily sweet hit.

The recent study and ensuing panic is a classic example of what happens when science reporting goes wrong. The study itself was fairly simple — researchers looked at whether high-fructose corn syrup was associated with an increased risk of bowel cancer. They found that, while it didn’t make more tumors appear, corn syrup did make any tumors that did appear bigger at intake amounts roughly equivalent to a can of Coke a day. In other words, a can of soda per day made tumors bigger, on average, which is what we scientists like to call “not ideal”.

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Pictured: Science, probably

But before you run screaming from your fridge, it’s worth noting that this study didn’t definitively prove that corn syrup causes cancer, at least in people.

You see, the study was done in mice.

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I’ve written before about why extrapolating directly from rodent studies to humans is a bad idea, and the reasons basically boil down to “mice aren’t people, they’re mice”. You can’t just take research done in mice and apply it directly to people.

It’s also worth noting that this research didn’t actually demonstrate that corn syrup caused cancer. What actually happened is that, in mice who were given cancer injections*, mice who drank corn syrup had tumors that were a bit bigger than the mice drinking water. Now, this isn’t great, obviously, but it’s also not evidence that corn syrup causes cancer, which is what most media stories painted it as.

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Pictured: Poison for mice? Maybe. For humans? Well, also maybe, but maybe not specifically cancer

Whenever you see a headline talking about risks that only involves research in mice, it’s a good idea to check if we’ve looked at the same thing in people. It turns out, with sugar and cancer, we already have.

Our current best evidence seems to indicate that sugar — or high fructose corn syrup — by itself, does not cause cancer in people.

Now, high intakes of sugary foods can contribute to obesity. And being obese raises your risk of all sorts of cancers. But obesity is caused by a whole host of social and environmental factors, a wide plethora of foods, so singling out a single ingredient and labeling that as a cause of cancer outside of the general issues of obesity is pointless.

It’s a bit like saying that pie crusts cause diabetes — if you eat enough of them, maybe that’s true, but it’s not really the pie crusts’ fault.

Does this mean that high-fructose corn syrup is fine to eat? Well, yes. Most foods in moderation are “fine”. You should obviously limit your intake, and try to stay away from some of the more processed foods that contain corn syrup, but the occasional can of soft drink isn’t going to kill you.

Sugar-sweetened foods are calorie heavy and should probably be eaten only in moderation.

That doesn’t mean they’re giving you cancer.

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*Note: technically, they had cancer induced through the introduction of a carcinogenic agent over a period of weeks, but let’s be honest “cancer injections” sounds a lot better

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