DOES adding sugar to your diet make you fat? The World Health Organization thinks so. Last week it recommended that we get no more than a tenth of our calories from the sweet stuff. It hopes this will help to halt a global epidemic of obesity that threatens to overwhelm health services around the world.
But the American sugar industry says the recommendation is flawed, relies on bad science, and undermines the credibility of the organisations supporting it. Cutting back on sugar will not improve our health, but it will jeopardise the economies of developing nations dependent on sugar exports.
An investigation by 快猫短视频 has established that there is no universal agreement about what constitutes a healthy level of sugar in our food. But there is an emerging consensus that consuming too much of it does more than just cause dental decay. Dietary sugar 鈥� and especially the refined sugars typically added to soft drinks, sodas, cookies and confectionery 鈥� is emerging as a potential contributor to obesity and a major aggravator of diabetes.
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The US Sugar Association is up in arms over the release of a joint report by the WHO and the UN Food and Agriculture Organization called Diet, Nutrition and the Prevention of Chronic Disease. The report recommends that no more than 10 per cent of our calories should come from added sugar. The Sugar Association claims that the most credible scientific evidence, from the US Institute of Medicine, fails to support such a low figure and it has tried to stop the report being launched. Not only that: it has also threatened to lobby Congress to suspend the US鈥檚 $406-million-a-year contribution to the WHO. 鈥淭axpayers鈥� dollars should not be used to support misguided, non-science-based reports which do not add to the health and well-being of Americans, much less to the rest of the world,鈥� the association says.
The WHO has responded with a vigorous defence of its report (see 鈥淪weet and sour鈥�, by WHO director-general Gro Harlem Brundtland). Independent experts contacted by 快猫短视频 are surprised by the Sugar Association鈥檚 claims. 鈥淭en per cent has been the orthodox position for 30 years,鈥� says Jack Winkler of the Food and Health Research consultancy in London. It has been recommended time and again by independent government experts around the world.
When the 10 per cent limit was specified, it was designed to prevent tooth decay. At the time sugar was thought to contribute to obesity only by making fatty food tastier, tempting people to eat more. Now that view is changing. Animal and human studies over the past two or three years suggest refined sugar affects our metabolism in ways that can make us fatter and lead to diabetes. 鈥淲e have a metabolic theory and mechanism beyond simple calorie intake,鈥� says Winkler.
For instance, a team at the Hannah Research Institute in Ayr, Scotland, led by cell biochemist Victor Zammit, is investigating the causes of 鈥渟yndrome X鈥�, a steady deterioration in the body鈥檚 ability to handle sugar. People with the syndrome first put on weight, and eventually develop a form of diabetes (快猫短视频, 1 September 2001, p 26).
The human body breaks down common sugar, sucrose, into glucose and fructose, which then flood into the bloodstream and liver. To get the blood levels down again, the body produces a surge of insulin to tell cells to absorb more glucose. But the suspicion is that these spikes of glucose and insulin have detrimental effects. If insulin levels surge too often, cells begin to ignore the hormone鈥檚 signal to mop up excess sugar. The pancreas produces more insulin to compensate, but eventually it burns out and stops producing insulin altogether. The end result is diabetes. Moreover, fructose stimulates the liver to form fatty substances called triglycerides, which can enter the bloodstream and be laid down as fat.
Crucially, the body copes differently with highly refined sugar, which is absorbed quickly, and the sugars in fruit, vegetables and wholegrains. To release these sugars the body first has to digest the plant cells containing them, so they enter the bloodstream more slowly, avoiding the damaging surges.
These physiological studies are reinforced by research indicating that excess sugar is bad for people鈥檚 health. In October 2002, nutritionists led by Arne Astrup of the Royal Veterinary and Agricultural University in Copenhagen showed that men put on weight if they drank soft drinks containing added sugar for 10 weeks, whereas a control group drinking similar beverages with artificial sweeteners lost weight (American Journal of Clinical Nutrition, vol 76, p 721). 鈥淭he difference between men in the groups was about 2.6 kilograms,鈥� says Astrup. 鈥淭hat鈥檚 a substantial figure for just 10 weeks.鈥� The blood pressure of those given sugar-sweetened drinks had also risen by the end of the experiment.
Over 27 million people in the US regularly eat a diet in which fructose contributes 17 per cent of each day鈥檚 calories. John Bantle at the University of Minnesota at Minneapolis and his team fed two dozen healthy volunteers a diet containing this amount of fructose for just 6 weeks. In men, triglyceride levels rose by a third, adding weight to the theory that 鈥渟yndrome X鈥� is real.
The Sugar Association criticises the WHO/FAO report for ignoring the US Institute of Medicine (IOM) research last year. This concluded there is insufficient evidence to set an upper level for added sugars and recommended people鈥檚 calorie intake from added sugar should not exceed 25 per cent. 鈥淚t should have been taken into consideration鈥he reason it wasn鈥檛 is it doesn鈥檛 support their previous guideline of 10 per cent,鈥� said SA president Andy Bristoe when contacted by 快猫短视频.
鈥淲e didn鈥檛 ignore it. Our group is aware of all the expert reports, but saw no reason to change the [guideline],鈥� says a WHO spokesperson. The IOM is also distancing itself from the association鈥檚 interpretation of its report. 鈥淲e are not recommending people have a quarter of their energy from sugar,鈥� says an IOM spokeswoman. 鈥淭hat鈥檚 the maximal level. Above that, people would not be getting levels of essential nutrients to keep them healthy.鈥�
The association says a report in 2001 by Anne Mardis, then at the US Department of Agriculture in Alexandria, Virginia, was similarly ignored. Mardis, now at Nebraska鈥檚 Department of Health and Human Services in Lincoln, concluded that 鈥渢he intake of added sugars is not directly related to diabetes, heart disease, or obesity鈥�. But Mardis points out that her report stated clearly that children should limit sugar intake to avoid it displacing other important foods and nutrients.
James Hill of the Health Sciences Center at the University of Colorado in Denver is cautious about making unequivocal claims for the health benefits or otherwise of sugar. 鈥淲e have a controversy because we don鈥檛 have any compelling data,鈥� he says. 鈥淭here are a couple of studies implicating sugar in the development of obesity, [but] these alone don鈥檛 provide the rigorous data we need to reach a conclusion.鈥�
Most researchers contacted by 快猫短视频 agree, however, that the WHO recommendation is a reasonable compromise. Nutritionist Walter Willett at the Harvard School of Public Health says added sugar 鈥渋s nutritionally dead鈥�, because it stops people eating more healthy foods. Astrup agrees, saying that consuming rich foods or sugary drinks means people eat less of other foods that contain more minerals and vitamins.
Susan Jebb, who heads Britain鈥檚 Medical Research Council鈥檚 Nutrition Unit in Cambridge, says that the epidemiological data gathered so far linking excess added sugar to obesity is impressive. Though the link is not yet conclusive, she suspects that cutting down on sugar could turn out to have significant benefits, while posing no obvious risks. Willett goes further. 鈥淗igher amounts of rapidly absorbed carbohydrate, including sugar and refined starches, have adverse metabolic effects, including increasing serum insulin and triglycerides, and reducing the level of [beneficial] cholesterol,鈥� he says. 鈥淚n our large epidemiological studies, we have seen higher intakes of these carbohydrates are associated with greater risks of coronary heart disease and diabetes.鈥�
At stake in these sugar wars is the health of generations to come. The rate of obesity has soared in recent times, not just in the US and Europe (see Graph), but also in the developing world. The fear is that the trend will get worse, and that the US sugar industry鈥檚 attitude is not helping. 鈥淭hey have enormous clout,鈥� says Neville Rigby of the International Obesity Task Force in London. 鈥淭hey have affected the agenda for the US till now, and are trying to influence it for the whole world.鈥�
