We all know sugar is bad for us. Diet books have been screaming for decades that the single worst thing that you can put in your body is a droplet of that sweet, sweet goodness. Celebrity diets may differ in many ways, but they all tell us to avoid that sweet, sticky powder.
Which makes the recent media furore about sugar all that much more believable. Headlines around the globe have been screaming for the last week that sugar is giving us all cancer. Apparently, a small glass of fruit juice is enough to push you over the edge into the scariest of C-words.
It must be true because of SCIENCE!
The good news is that you probably don’t have to worry too much about sugar giving you cancer. The bad news is that too many sugary drinks are still not great for your health.
The study that has everyone fearing for their lives was a large epidemiological trial using a cohort of people in France. Basically, the researchers took a large group of people — over 100,000 — asked them a bunch of questions about their lives, and then monitored them for a decade. They then split them into groups based on how much sugar they drank — either from juice or sugar-sweetened beverages like Coke/Pepsi — and looked at how many people in each group got cancer.
After controlling for a number of potential confounding variables — things that can cause both increased sugar consumption and cancer — the researchers found that people who drank more sugary beverages were at a ~20% higher risk of cancer. They also found that drinking just 100ml a day — one bottle of Coke a week, roughly — could increase your risk of cancer!
It’s enough to put me off my Pepsi.
They also found that this wasn’t limited to the usual suspects: even fruit juice was associated with an increased cancer risk. The only safe option — aside from water — were artificially sweetened drinks, which were not associated with any health issues in this research.
Fortunately for those of us who have a sweet tooth, there’s no need to go running from the soft drinks just yet. There’s a bit more to this story.
There are a few issues that make this study a bit difficult to apply to the average person’s life. The first thing to note is that cancer isn’t one disease. Cancer is a huge group of conditions that we lump together because it’s easier than admitting that health is complex.
In this study, for example, they looked at a whole range of different cancers, including pre/postmenopausal breast cancer, prostate cancer, lung cancer, and bowel cancer. And, while there was an increased risk from drinking sugar for all “cancer”, this was only true for one specific subtype: premenopausal breast cancer.
In other words, the study found no increased risk from sugar consumption for prostate cancer, lung cancer, bowel cancer, and a host of other cancers. It’s not unlikely that the increased risk of cancer is not applicable to many people, especially considering that this study was conducted mostly on the relatively wealthy French.
The absolute increased risk that the study found was also a lot less scary than the headlines implied. While the “20% increase” that hit the news sounds terrible, this actually equates to an absolute increase in risk of about 1%. To put it another way, on average about 3 people per 100 got cancer in the lowest risk group. If they all quadrupled their sugary drink intake to match the highest risk group, that number would go up to 4 people per 100.
This was also an observational study. While the researchers did an amazing job, it’s impossible from this sort of study to directly infer causality. It’s entirely possible — even likely — that some other factors might be causing both the cancer and the increased sugar drinking. For example, we know that wealthier people drink fewer soft drinks, and we know also know that they are at a reduced risk of many cancers, so being rich might be confounding the relationship between cancer and sugar drinking. While the study attempted to control for factors like this, there’s ultimately only so much you can do.
It’s possible that sugar was causing cancer. It’s possible it was something else entirely.
Ultimately, it’s hard to know what to take home from this study. People who drank sugar were at an increased risk of cancer, but it’s possible that’s only true for a few cancers. The risk increase seems impressive at first, but the absolute difference was very small, and even then we aren’t sure if there’s a causal connection or if this is just due to social factors like income.
A better headline for this study might be: “Sugary drinks are associated with some cancers in observational study, but risk increase is very small”.
Sadly, that sells fewer papers.
The worst thing about all of this is that too much sugar is definitely bad for your health. We should all probably reduce our consumption of excess sugar, but not because we’re terrified of cancer. Sugary drinks are calorie-dense and nutrient-poor foods that provide little except deliciousness, and cutting back is almost certainly going to be good for your health regardless of whether it reduces your cancer risk or not.
Are sugary drinks giving you cancer? The jury’s out, but at the moment it doesn’t seem very likely. Other studies have failed to find a link between sugary drinks and cancer, some of them even bigger than this one.
Are they bad for your health? Well, that’s a difficult question, but the answer is “probably”. Sugary drinks, like chocolate, candy, and other delicious sweet things, are probably best consumed in small doses.
Just don’t worry too much about your orange juice giving you cancer.
It’s all much more complicated than that.
You can now listen to Gid on the Sensationalist Science podcast for your weekly dose of scientific shenanigans and media muddling: