The deadly legacy of America's fields of gold

Richard Nixon is remembered for his infamous part in the Watergate scandal, but his lasting legacy may be a burgeoning army of people in the West who are too fat.

In the 1970s, Nixon's Agriculture Secretary, Earl Butz, realised that farmers were harvesting more corn than they knew what to do with thanks to more efficient, industrialised methods. His answer was to champion increased production and use of high-fructose corn syrup, which has undergone enzymatic processing to convert some glucose into fructose. The fructose-rich sweetener – now nicknamed "devil's candy" in the US – was cheaper and sweeter than sugar. By the 1980s, high-fructose corn syrup (HFCS), called glucose-fructose syrup in the UK, was the favourite substitute for sugar worldwide, finds a new BBC series, The Men Who Made Us Fat, starting this week.

A growing body of research suggests that fructose, contained in both glucose-fructose syrup and table sugar, has strong links to obesity, as it suppresses the action of the hormone leptin, which tells the body that the stomach is full. The endocrinologist Robert Lustig told the BBC: "Leptin goes from your fat cells to your brain and tells your brain you've had enough." But when the liver is overloaded with sugar, leptin stops working. "It makes your brain think you're starving and now what you have is a vicious cycle of consumption, disease and addiction."

Dr Jean-Marc Schwarz, a food scientist at San Francisco General Hospital, said: "Some sugar will be converted to fat, and fructose is one sugar that can be easily converted to fat. It's not comparable to lead or mercury: it's the quantity that makes it toxic."

The substance is used widely in the US, especially in soft drinks, for flavouring and to improve shelf life. In the UK it is found in a range of products including McVitie's Hobnobs, Jaffa Cakes and Classic Rich Tea biscuits, Carte D'Or ice cream, Lucozade Energy Orange and Apple flavours, Yop yoghurts, McDonald's Big Mac sauce, two flavours of Kellogg's Special K bars and Kellogg's Nutri-Grain Soft & Fruity.

Kellogg's confirmed yesterday that it had removed glucose-fructose syrup from its All-Bran and Corn Flakes in 2009, but it remains an ingredient in some snack bars: "We use glucose-fructose syrup in a few of our snacks for texture reasons. We always ensure everything we use is approved by the Food Standards Agency." McVitie's has just announced it will add golden syrup to its Hobnob biscuits but could not confirm that this would mean dropping glucose-fructose syrup. And GlaxoSmithKline's Lucozade, which includes 24 per cent glucose-fructose syrup in its ingredients, said it "does not contain high-fructose corn syrup".

Two-thirds of the British public are overweight, and a quarter are classified as obese. The average person in the UK is three stone heavier than 50 years ago, and obesity costs the NHS more than £4bn a year.

Dr Richard Johnson wrote in The American Journal of Clinical Nutrition in 2007: "The combination of table sugar and glucose-fructose syrup has resulted in an additional 30 per cent increase in overall sweetener intake over the past 40 years."

Increased sugar intake is coupled with increasingly sedentary lifestyles: the average person now watches 26 hours of television per week; and an increase in portion sizes and snacking: the average woman now consumes 2,178 calories a day as opposed to 1,818 in the 1950s.

Laboratory research by Princeton University concluded that long-term consumption of glucose-fructose syrup resulted in "abnormal increases in body fat, especially the abdomen". Professor Bart Hoebel, who led the study, said: "Some people have claimed that glucose-fructose syrup is no different from other sweeteners when it comes to weight gain and obesity, but our results make it clear that this just isn't true."

Other research has suggested it may be linked with the formation of beta-amyloid plaques in the brain, thought to cause Alzheimer's, heightened blood pressure, and memory and learning impairment.

Zoe Harcombe, author of The Obesity Epidemic: What Caused It? How Can We Stop It?, told The Independent on Sunday: "I think it's hideous, one of the most evil products we've introduced into our diet. It's cheap and it adds shelf life to products, but has no nutritional value whatsoever." She believes that we should also be curbing our consumption of fruit, high in fructose. "It is certainly not helping the obesity epidemic," she said.

Dr Carrie Ruxton, a dietician, said: "Fructose is probably not as bad as we think at current UK levels. Short-term studies on very high doses have produced negative effects on blood lipids, but longer-term studies on more normal amounts (up to 50g a day) do not show these effects. Concerns about the use of glucose-fructose syrup in drinks may relate to the impact of the drinks themselves rather than the fructose content."

Helen Bond, of the British Dietetic Association, said: "There are a lot of frightening trials about the potential effects of glucose-fructose syrup. We need more scientific work on its effects on the body."

'The Men Who Made Us Fat' goes out on BBC2 at 9pm on Thursday