Professor Ian Young, Queenís University Belfast, and SACN Group Member
Almost 25% of Brits are obese. Treating obesity and the knock on effects on our health is costing the NHS £5.1 billion every year. Sugar is thought to be a source of those excess pounds, says a report published earlier this year by the Scientific Advisory Committee on Nutrition. It advises we should be halving our consumption but how we do this is proving controversial. Professor Ian Young, Queenís University, Belfast was one of the authors of that very report and Chris Smith asked him the question that's on everyone's lips: Why do we need to slash our consumption...
Ian - Sugars are small molecules, which fall into the group of monosaccharides or disaccharides and, in particular, in the SACN report we have used the term Ďfree sugars,í which means the sugars which are added to foods or drinks by the manufacturer, plus the sugars which naturally are present in honey, and syrups and unsweetened fruit juices. And we donít count the sugars in the cellular structure of foods, so whole fruits and vegetables.
Chris - Because, for instance, I could argue that a potato is full of carbohydrates, but thatís lots of sugar molecules stuck together to make another bigger molecule called starch, which is a very different beast than the glucose, sugar molecules, that make it up, isnít it?
Ian - It is, so the SACN report deals with carbohydrates in total, which include the complex carbohydrates like starch, the sugars as Iíve described, and also fibre. We didnít find any harmful effects of the amount of carbohydrate which was in the diet. So the recommendation is that it should remain at around 50% but we did find some harmful effects around free sugarsÖ
Chris - When you say 50%, do you mean 50% of the calories that a person takes in should come from some sort of carbohydrate source?
Ian - Yes around 50% of calories should come from carbohydrate source.
Chris - How much are people eating at the moment?
Ian - The amount of carbohydrate is appropriate, itís around between 50 and 60% but, in terms of sugars, itís running between 12% and 15% of energy from free sugars, which we think is far too much.
Chris - And so what are you recommending instead?
Ian - We are recommending that free sugars should be reduced to less than 5% of energy intake.
Chris - And why are you suggesting that?
Ian - Well the harmful effects we found with free sugars were firstly, an increased risk of tooth decay in large prospective studies, secondly, we found that in adults when people eat a diet with a high sugar content that they tend to consume more energy overall, and thatís likely to increase the risk of obesity and, for sugar sweetened drinks in particular, increased intakes are associated with increased risk of type 2 diabetes in adults.
Chris - Now about 20 years ago, the proportion of the population of the average western country that was obese was about 10%, itís now about 30%. Can we account for why thereís been this dramatic difference in the last 20 years?
Ian - So the dominant theory is that itís due to an imbalance between energy intake and energy utilisation. So people have been eating more calories, and certainly the increase in sugar intake is likely to play a part in thatÖ.
Chris - But has that really changed in 20 years? Are people dramatically eating three times different amounts of things now compared with what they did 20 years ago?
Ian - No, theyíre eating somewhat more but, in addition to that, thereís evidence of reduced energy expenditure and itís the balance between the two, the energy intake and the energy utilisation, which probably leads to the increased risk of obesity.
Chris - So why do you think that sugar, and reduction of sugar is the answer then. Because if itís down to lifestyle factors and activity, why will just cutting out some sugar Ė halving it from 10-15% down to around 5% of calorie intake, why will that make a difference?
Ian - So, I think it will make a difference. I donít think anybody would say that itís the answer. If you eat less free sugars, then you are better able to regulate your energy intake and we believe if sugar intake reduced from 10% of energy to 5%, that on average people would eat 100 calories per day less if you were an adult, and that would certainly make a contribution to reducing the incidence of obesity.
Chris - Ian, is there any evidence that people get Ďhookedí on sugar, or is that just a figure of speech?
Ian - Certainly people like sugar but the idea that sugar is addictive in the way that, for instance, some drugs of abuse are addictive, I donít think thereís any significant evidence to support that.
Sorry, but I think you've missed a significant part of the debate. The data (the information not funded by the food industry, whose scientists should recuse themselves from this debate on obvious grounds of conflict of interest) show that biochemistry affects behavior, not the other way around. Fructose is actually a toxin and is processed biochemically only in the liver, via the same pathway as alcohol. It is not an acute toxin, unlike alcohol (fermented fructose), but it is the identical chronic toxin. Look at the studies on the use of an endocrine drug called octreotide to treat hypothalamic obesity in kids with brain tumors, which led to studies of regular obesity in adults. The constant high insulin (due to overdosing on fructose (via HFCS or sucrose)) causes leptin resistance, which is why we eat too much; our bodies think we're starving, SO we eat more and exercise less. When given octreotide to block a part of that pathway, adults spontaneously moved more and ate less. I refer you to the work of the pediatric neuroedocrinologist Robert Lustig and his colleagues at UCSF and the Institute for Responible Nutrition for the rigorous and massive studies they have done to bring this crucial point to light. Metabolic syndrome is bankrupting many healthcare systems around the world, and following the old party line isn't going to work. It hasn't worked for 30 years. I am not a scientist, but Lustig and his colleagues are. I find their evidence credible and compelling. The recommendations you presented were admirable, but without conviction or teeth, and you're still blaming an unsuspecting public and allowing a complacent and complicit legislative body to pass the buck. The food and beverage companies are behaving like the tobacco companies, and they are just as culpable. If you truly want to impact public health for the better, please, show all sides of this debate. C. Boyer, Thu, 18th Feb 2016