Question: A recent current-affairs show on TV had a segment on sugar-free diets. I’m a bit confused after watching this, as one expert said sugar was killing us and should be avoided, while another said sugar was fine in moderation. What do you think?
Answer: According to a recent article in scientific journal Nature, sugar should be placed in the same category as alcohol and tobacco because of its deadly effects on our health. “Sugar is cheap, sugar tastes good and sugar sells, so companies have little incentive to change,” wrote Dr Robert Lustig and co-authors, who recommended using regulatory measures, such as taxation and restrictions on sales to children, to reduce sugar consumption.
But there’s one major problem with Lustig’s suggestions. “They’ve missed a step, and that is, let’s get the science right,” says Dr Jim Mann, an endocrinologist and professor in human nutrition and medicine at the University of Otago. Mann was surprised to see the “somewhat hysterical” article in Nature. Lustig also appeared in the recent current-affairs television segment on sugar-free diets. “I think [Lustig] should look at his experimental data a bit more before worrying about how we should legislate against sugar.”
Mann is the director of the Edgar National Centre for Diabetes and Obesity Research and the World Health Organisation’s Collaborating Centre for Human Nutrition, and his WHO responsibilities prevent him from working with the food industry, so there is little reason to suspect his viewpoint is based on anything but scientific evidence. Sugar is a major contributor to energy density in foods, and energy density is a major contributor to the epidemic of obesity, which is a major contributor to the epidemic of diabetes, not to mention cancer of the large bowel, post-menopausal breast cancer and more, says Mann.
But what Lustig and his University of California San Francisco colleagues postulate is that there is something peculiar about sugar: that even when it is consumed in moderate amounts, it is converted rapidly to triglycerides, which are then deposited in the liver and predispose the individual to metabolic syndrome. Metabolic syndrome is a cluster of disorders that increase the risk of cardiovascular disease and diabetes. These disorders can include obesity, high blood pressure, insulin resistance, high bloodsugar levels, raised triglyceride levels and low HDL cholesterol levels. The WHO’s Nutrition Guidance Advisory Group, of which Mann is a member, is investigating the effect of sugars on health.
“We’re working on just how great the contribution is between sugar and obesity. Is it all sugars, or just some kinds of sugars? Is it sucrose? Is it sugar-sweetened drinks or whatever?” But does sugar have an effect on health that has nothing to do with its calorie content? Mann says it’s still impossible to answer that question with any certainty, because there simply isn’t good enough data from human trials.
“My feeling is that the detrimental effect of sugar comes through obesity largely” – in other words, through people simply consuming sugar to excess. “People often say to me that nutritional science is a pathetic science because it always changes its mind. The answer is it doesn’t change its mind – it’s people who misinterpret or overinterpret the data,” says Mann. And the sugar debate that Lustig ignited may fall into that category. “I’m a great believer that one should avoid sugar in excess, and if it transpires that the Lustig philosophy is correct, we’ll have to look again.”
Those who enjoyed a bit of chocolate over Easter will be pleased to hear how Mann sums things up: “Sugar’s not the most deadly, terrible substance that’s going to poison people, particularly if consumed in moderation.”
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