Opinion

Sugar, it seems, is the latest on-trend food topic. Scientists and the news media have been loudly proclaiming the dangers of sugar consumption and presently there seems to be a never-ending supply of journal articles, news stories and TV shows reporting the dangers of our excessive sugar consumption. Even the prestigious science magazine, Nature, has been publishing on the topic.

A number of personalities, scientists included, have become quite evangelical in their crusade against sugar, calling for the public to be told “the toxic truth about sugar”: that is, sugar may be as addictive as tobacco and alcohol, causing terrible danger to our livers and brains, and it should be regulated in the same sort of way. Meanwhile, it seems that the lay public is already quite aware that eating too much sugar is not a good idea and, quite fairly, wonders why scientists are being paid to research something that is blindingly obvious.

I was thrilled when our University of Otago-based systematic review and meta-analysis examining the effects of sugar consumption on body weight was published in the prestigious British Medical Journal last year. This work was commissioned by the World Health Organization to inform the new recommendations on dietary sugar intakes which were released for public consultation in February.

The review continues to be widely reported in the world's media and has, so far, gathered a healthy number of scientific citations. In New Zealand our work was reported on the Stuff media website with the dramatic headline “Scientists confirm sugar is a diet evil”. The public's response, however, was quite humbling: “What's next? 'Man lands on the moon'” and “No s*** Sherlock” were fairly typical comments.

So what is it about sugar that is keeping it in the news?

Well, possible toxicity dangers aside, the notion that excessive sugar consumption contributes to increased risk of dental caries, obesity and obesity-related diseases is not universally accepted. Not surprisingly, the sugar and food manufacturing industries (i.e. Big Sugar) are not so keen to see sugar unfairly maligned. Mirroring the well-described tactics of Big Tobacco, Big Sugar has invested considerable resources to convince the public, health professionals and governments that sugar has an important role in a healthy, everyday diet and that there is no justification for recommending that sugar intakes should be limited.

Big Sugar has been quick to criticise the evidence put forward by the emerging anti-sugar lobby – and, to be honest, it's relatively easy to criticise. There is a surprising lack of high quality, long-term human intervention studies examining the effects of sugars on disease and risk factors for disease.

The toxicity claims for sugar are largely based on ecological association studies (for example, correlation studies linking increasing sugar intakes over time with increasing rates of obesity), animal feeding studies and human studies examining the effects of extreme intakes of sugars that bear little relationship to the diets of most people. High quality independent research is still very much needed to verify claims that sugar increases health risks.

Public health recommendations cannot be based on anecdotal evidence, or animal studies. In 2003 WHO released a new population recommendation for sugar intakes, stating that free sugars should comprise less than 10 per cent of total energy intake. This was based on data linking sugar intake with dental caries and the fact that free sugars simply add extra energy to diets without other nutritional benefits.

However, the recommendations met with solid opposition from Big Sugar, which attacked the quality of the science underpinning them. There was limited evidence, they argued, to link sugar intakes with obesity. Furthermore, the WHO processes for developing the recommendations were said to lack transparency and to have been developed by a biased selection of experts. Big Sugar preferred an Institute of Medicine report suggesting that we could safely consume up to 25 per cent of our energy from free sugars without compromising adequate intake of other essential nutrients and, to this day, continue to misconstrue this figure as a “reasonable” intake limit for sugar.

WHO has now introduced a more robust process for developing recommendations and guidelines. This process requires systematic reviews of the evidence (with meta-analyses, if possible) and involves a systematic evaluation of the quality of the evidence on which a recommendation is based, hence our research: an objective review of the evidence from all published human trials and cohort studies which examined the effects of sugars on body weight.

Though we confirmed what the public already knew, we provided the most convincing evidence, to date, that intake of free sugars is a determinant (but not the only determinant) of body weight in free-living people consuming relatively normal diets.

Sugary foods and drinks are highly palatable and it's easy to consume too much of them, which can ultimately lead to weight gain. Since free sugars add unnecessary extra calories to our diets without providing other nutritional benefits, they could be removed from our diets without harm. Not surprisingly, Big Sugar is still not convinced that sugar is a problem, although the evidence and population dietary guidelines recommending reduction in the intake of free sugars are getting harder to dismiss.

To me, there is no doubt that sugary foods and drinks are too readily available, too heavily promoted and excessively consumed. It is becoming increasingly clear that excessive intake of sugar is linked to obesity and related diseases, and that Big Sugar is fighting a losing battle. We do need to look at ways to reduce population intakes of free sugars, but this needs to be done carefully to avoid consumers swapping sugar-laden junk for non-sugar junk. Profit-driven food manufacturers will readily provide new food solutions to fill that gap in our diets.

But is sugar toxic and should we ban it? I personally don't think so – or at least the evidence isn't sufficient to have me rethinking my comfortable relationship with sweet treats yet. And, anyway, our celebrations would be so less interesting without, at least, a little bit of sugar.

Photo: Alan Dove