Described variously as ‘toxic’ and ‘the new tobacco’, sugar has had a bad press recently. Now, as a new campaign group urges manufacturers to cut the amount of sugar they add to their food and drinks, we investigate why

Millions of people in the UK admit to having a ‘sweet tooth’. But could this predilection for sugary treats actually be damaging our health because sugar is, as some suggest, simply bad for us?

Many who have read media headlines such as ‘Sugar is the new tobacco’ and ‘The toxic truth about sugar’ will be worried – your customers included. Behind these headlines lie claims that sugar is addictive and is the reason why so many of us are becoming overweight and susceptible to health problems such as diabetes.

What exactly is sugar?

Sugar is a type of carbohydrate that is derived from plants. All sugar is natural, whether it is intrinsic (i.e. part of the cellular structure of items such as fruit and vegetables) or extrinsic (e.g. found in processed foods and sweets or added to tea and coffee; milk sugar (lactose) is also an extrinsic sugar). No matter what its source, the body converts sugar (and all carbohydrates) into simple sugar molecules (monosaccharides) like fructose and glucose, which are the body’s main source of energy.

So what’s wrong with it?

Monosaccharides are stored in the body for use as energy, which is measured in calories. However, if they are stored for long enough, they may turn into fat. So, eating sugar beyond your daily calorie requirements can lead to weight gain – although the same can also be said of eating too many calories of any origin. The problem with sugar is that some people – including Professor Robert H Lustig from the University of California – believe that glucose and fructose can also cause serious health problems. Lustig’s article: ‘The toxic truth about sugar’ was published in the scientific journal Nature in February 2012.

Appearing on a Horizon TV programme entitled ‘Sugar v Fat’ earlier this year, Lustig explained why, in his opinion, sugar is bad for us. He believes that if we consume too much fructose, the body will turn it into liver fat, which can lead to problems such as heart disease, stroke and diabetes. He also believes in the ‘hormone hypothesis’, which states that the body’s fat cells respond to the release of insulin by holding onto fat and making more of it. Since glucose activates insulin production in the body, it is therefore also bad for us, he says.

However, the programme argued that studies supporting Lustig’s beliefs have been based on diets with unrealistically high levels of fructose. In addition, no comprehensive study has yet been conducted to find out whether the hormone hypothesis stacks up. The US Institute of Kidney Life science Technologies believes the theory is incomplete. “The notion that carbohydrates are the only driver of insulin is incorrect,” it says.

The British Nutrition Foundation (BNF) also refutes the claims. “It is important to highlight that the article in Nature, rather than being a scientific paper, was a commentary authored by Robert H Lustig and colleagues,” it says. “Current evidence does not support the dramatic claims about the association between sugar and health made by Lustig and colleagues. Sugar is a source of energy in our diet and it is certainly not ‘toxic’ in the amounts on average consumed in the UK.”

Does it cause type 2 diabetes?

There are two hypotheses surrounding the involvement of sugar in type 2 diabetes: firstly, that it causes the disease by making us gain weight, and secondly that it causes it via another mechanism. “The evidence for the first hypothesis is strong,” says Diabetes UK. “Eating too many calories – including those from sugar – can make a significant contribution to becoming overweight, and being overweight increases the risk of developing type 2 diabetes.”

But, says the charity, the evidence for the second hypothesis is less clear and further studies are needed. “The UK Scientific Advisory Committee on Nutrition is currently reviewing all evidence on dietary carbohydrate (including added sugar) and health, and we look forward to reviewing its recommendations when they are published in 2014,” it concludes.

Horizon also investigated the link between sugar and diabetes. It conducted a trial following twin brothers – one who ate a high sugar diet and one who ate a high fat diet – for one month. At the end of the month, it was the twin on the high fat diet whose blood glucose level had risen so high that he was teetering on the edge of diabetes. The blood sugar of the twin on the high sugar diet was unchanged. The reason for this is that eating a high fat diet can stop the body responding to insulin properly, so it produces too much glucose. This, in turn, raises blood sugar levels.

Is it addictive?

Horizon also dealt with the claim that ‘sugar is the new tobacco’ by exploring research being conducted in rats by Professor Paul Kenny from Mount Sinai School of Medicine. Interestingly, this research has found that rats fed on high sugar diets don’t tend to gain weight or become addicted to their food. Rats fed on high fat diets don’t become addicted either, although they do gain a little weight. However, problems begin when rats are fed a diet that is high in both fat and sugar – especially when the ratio is 50:50. On this diet of half fat, half sugar (in this case provided by cheesecake), the rats found it impossible to stop grazing; they gained weight and they became sedentary.

Kenny explained that this is because the 50:50 blend of fat and sugar activates the body’s hedonic (pleasure seeking) system. This is the same system that is activated by addictive substances like heroin, cocaine and tobacco. So while this research points to the conclusion that sugar is not ‘the new tobacco’, the same cannot be said for man-made foods that contain a 50:50 blend of fat and sugar.

Taking action on sugar

A group of specialists concerned about sugar and its effects on health have recently formed a pressure group called Action on Sugar. The group’s initial aim is to get manufacturers to reduce what it calls the ‘huge and unnecessary amounts’ of sugar in processed foods.

Action on Sugar has calculated that a 20 to 30 per cent reduction in sugar added by the food industry would result in a reduction of about 100 calories a day per person and more in those who are particularly prone to obesity. “This reduction in calorie intake is predicted to reverse or halt the obesity epidemic and will also have a significant impact in reducing the burden of chronic disease,” it says.

Should we stop consuming it?

Many of the UK’s major health charities and organisations have issued statements in support of Action on Sugar’s aim. However, they point out that obesity and chronic diseases like diabetes are not solely caused by sugar. According to the British Nutrition Foundation, eating too many calories from any source (fat, protein or carbohydrate) will lead to weight gain and may have a negative impact on health.

And Diabetes UK says that while cutting down on sugar can be important, people should do this because sugar contains lots of calories rather than because of any direct effect on the risk of developing type 2 diabetes. British Heart Foundation associate medical director Mike Knapton adds: “If manufacturers made small changes to the products we eat every day, it could make a difference to our waistlines. It would need to be combined with other measures to fully address the problem of obesity, but it’s a step in the right direction.”

Department of Health’s advice underlines this, advocating that we should all be eating a healthy, balanced diet.