A recent study published in the BMJ has found that sugar sweetened beverages, including pure fruit juices, were linked to an increased risk of cancers in a large French population followed for nine years, but artificially sweetened and unsweetened drinks were not.
Sugar and Metabolic Health
I have some sympathy with the new Prime Minister Boris Johnson whose instincts to reduce “creep of the nanny state” are probably for the good. Unfortunately, he has picked a bad place to start, suggesting that he might reverse the UK sugar tax which currently taxes drinks with more than 5g of sugar per 100ml. In fact, the UK sugar tax appears to be effective, and since it was announced in March 2016, UK manufacturers have dramatically reduced the sugar content of their drinks to the tune of a staggering 45 million kilos of sugar per year! (That’s about 100 million pounds (lb) for my American readers)
The main reason for the introduction of the sugar tax was an increasing amount of evidence linking sugar — and especially free-sugars found in sugar sweetened beverages — to cardiometabolic health. Studies so far have found that consumption is convincingly linked to an increased risk of weight gain, of being overweight, or obese; of a greater incidence of type 2 diabetes developing (independent of being overweight); of a higher risk of hypertension; and with cardiometabolic death.
In developed countries consumption of sugary drinks has increased dramatically among children. Indeed, this week the Daily Mail reported a nationwide poll that discovered one-in-five children never drink milk – even on cereal – yet more than a third drink a can of “fizzy pop” every day. The health implications cannot be underestimated and only strengthen the case for reducing “free sugars” in the diet.
For the highest consumers reducing sugar intake can have rapid and profound effects. In a 2015 post we reported on an intervention study that found reducing sugary drinks led to improved liver health of high sugar consuming children in just ten days.
Sugar and Cancer: is there a link?
Given the convincing case for the metabolic derangement caused by excess free-sugars in the diet one might expect a link between sugar-sweetened beverages and cancer which is increasingly recognised as a metabolic (rather than genetic) disease.
Obesity is a major risk factor for cancer, and just in the last few weeks Cancer UK stated that obesity now causes more cases of bowel, kidney, ovarian and liver cancers than smoking. Their advertising campaign, comparing obesity to smoking, has inevitably led to them being accused of ‘fat shaming’.
So although it is clear (to the degree that nutritional science is ever clear) that free-sugars are a risk factor for obesity, and obesity is a risk factor for cancer, The question remains whether excess free-sugars directly cause cancer.
Sugar and Cancer: the latest study
A recent study published in the BMJ has found that both sugar sweetened beverage and pure fruit juices, were linked to an increased risk of cancers, but that artificially sweetened and unsweetened drinks were not. Importantly, this finding was independent of BMI.
This study is based on data from the French NutriNet-Santé cohort which tracked over 100 000 participants from 2009 to 2018. Through yearly online questionnaires the habitual diet and self-reported health data of participants was collected, then analysed for correlations between sweetened drinks and cancers.
The study found a strong correlation between sugar-sweetened drinks and the incidence of cancer diagnoses.
“the consumption of sugary drinks was positively associated with the risk of overall cancer and breast cancer. 100% fruit juices were also positively associated with the risk of overall cancer. These results … suggest that sugary drinks, which are widely consumed in Western countries, might represent a modifiable risk factor for cancer prevention.”Sugary drink consumption and risk of cancer: results from NutriNet-Santé prospective cohort, BMJ, July 2019
There are several important take away points from this study:
- The overall cancer risk increased with the more sugar-sweetened fizzy drinks that were consumed
- The same held true for pure fruit juices which typically contain the same amount of sugar
- There was no association for artificially sweetened drinks
- These associations were independent of BMI
- The associations were strongest for breast cancer.
- No association was detected for prostate and colorectal cancers.
A strength of this study is that it is large-scale and had a good dataset. On the downside it is observational, so can only identify correlation not causation.
They say that Bo Jo is not good on the detail. So don’t expect him to read this post or the BMJ paper. Rather than wait for Government to act one way or the other do the libertarian thing and take responsibility for your own health and that of your family. Most of us know that sweetened fizzy drinks are not good for us. Let’s start to view 100% fruit juice in the same light.
What is already known on this topic
> The consumption of sugary drinks has increased worldwide during the last decades
> Sugary drinks are convincingly associated with the risk of obesity, which is a strong risk factor for many cancers
What this study adds
> The consumption of sugary drinks (including 100% fruit juice) was associated with an increased risk of overall cancer and especially of breast cancer
> In specific subanalyses, the consumption of 100% fruit juices were also associated with an increased risk of overall cancers
> The consumption of artificially sweetened beverages was not associated with a risk of cancer, but statistical power was probably limited owing to a relatively low consumption in this sample