By Julia Llewellyn Smith, The Daily Telegraph

A couple of years ago, an out-of-print book published in 1972 by a long-dead British professor suddenly became a collector’s item. Copies that had been lying dusty on bookshelves were selling for hundreds of pounds, while copies were also being pirated online.

Alongside such rarities as Madonna’s Sex, Stephen King’s Rage (written as Richard Bachman) and Promise Me Tomorrow by Nora Roberts; Pure, White and Deadlyby John Yudkin, a book widely derided at the time of publication, was listed as one of the most coveted out-of-print works in the world.

How exactly did a long-forgotten book suddenly become so prized? The cause was a ground-breaking lecture called Sugar: the Bitter Truth by Robert Lustig, professor of paediatric endocrinology at the University of California, in which Lustig hailed Yudkin’s work as “prophetic”.

“Without even knowing it, I was a Yudkin acolyte,” says Lustig, who tracked down the book after a tip from a colleague via an interlibrary loan. “Everything this man said in 1972 was the God’s honest truth and if you want to read a true prophecy you find this book… I’m telling you every single thing this guy said has come to pass. I’m in awe.”

Posted on YouTube in 2009, Lustig’s 90-minute talk has received 4.1 million hits and is credited with kick-starting the anti-sugar movement, a campaign that calls for sugar to be treated as a toxin, like alcohol and tobacco, and for sugar-laden foods to be taxed, labelled with health warnings and banned for anyone under 18.

Lustig is one of a growing number of scientists who don’t just believe sugar makes you fat and rots teeth. They’re convinced it’s the cause of several chronic and very common illnesses, including heart disease, cancer, Alzheimer’s and diabetes. It’s alsoaddictive, since it interferes with our appetites and creates an irresistible urge to eat.

This year, Lustig’s message has gone mainstream; many of the New Year diet books focused not on fat or carbohydrates, but on cutting out sugar and the everyday foods (soups, fruit juices, bread) that contain high levels of sucrose. The anti-sugar camp is not celebrating yet, however. They know what happened to Yudkin and what a ruthless and unscrupulous adversary the sugar industry proved to be.

The tale begins in the Sixties. That decade, nutritionists in university laboratories all over America and Western Europe were scrabbling to work out the reasons for an alarming rise in heart disease levels. By 1970, there were 520 deaths per 100,000 per year in England and Wales caused by coronary heart disease and 700 per 100,000 in America. After a while, a consensus emerged: the culprit was the high level of fat in our diets.

One scientist in particular grabbed the headlines: a nutritionist from the University of Minnesota called Ancel Keys. Keys, famous for inventing the K-ration – 12,000 calories packed in a little box for use by troops during the Second World War – declared fat to be public enemy number one and recommended that anyone who was worried about heart disease should switch to a low-fat “Mediterranean” diet.

Instead of treating the findings as a threat, the food industry spied an opportunity. Market research showed there was a great deal of public enthusiasm for “healthy” products and low-fat foods would prove incredibly popular. By the start of the Seventies, supermarket shelves were awash with low-fat yogurts, spreads, and even desserts and biscuits.

But, amid this new craze, one voice stood out in opposition. John Yudkin, founder of the nutrition department at the University of London’s Queen Elizabeth College, had been doing his own experiments and, instead of laying the blame at the door of fat, he claimed there was a much clearer correlation between the rise in heart disease and a rise in the consumption of sugar. Rodents, chickens, rabbits, pigs and students fed sugar and carbohydrates, he said, invariably showed raised blood levels of triglycerides (a technical term for fat), which was then, as now, considered a risk factor for heart disease. Sugar also raised insulin levels, linking it directly to type 2 diabetes.

Factsheet: Type 2 diabetes

When he outlined these results in Pure, White and Deadly, in 1972, he questioned whether there was any causal link at all between fat and heart disease. After all, he said, we had been eating substances like butter for centuries, while sugar, had, up until the 1850s, been something of a rare treat for most people. “If only a small fraction of what we know about the effects of sugar were to be revealed in -relation to any other material used as a food additive,” he wrote, “that material would promptly be banned.”

This was not what the food industry wanted to hear. When devising their low-fat products, manufacturers had needed a fat substitute to stop the food tasting like cardboard, and they had plumped for sugar. The new “healthy” foods were low-fat but had sugar by the spoonful and Yudkin’s findings threatened to disrupt a very profitable business.

As a result, says Lustig, there was a concerted campaign by the food industry and several scientists to discredit Yudkin’s work. The most vocal critic was Ancel Keys.

Keys loathed Yudkin and, even before Pure, White and Deadly appeared, he published an article, describing Yudkin’s evidence as “flimsy indeed”.

“Yudkin always maintained his equanimity, but Keys was a real a––-, who stooped to name-calling and character assassination,” says Lustig, speaking from New York, where he’s just recorded yet another television interview.

The British Sugar Bureau put out a press release dismissing Yudkin’s claims as “emotional assertions” and the World Sugar Research Organisation described his book as “science fiction”. When Yudkin sued, it printed a mealy-mouthed retraction, concluding: “Professor Yudkin recognises that we do not agree with [his] views and accepts that we are entitled to express our disagreement.”

Yudkin was “uninvited” to international conferences. Others he organised were cancelled at the last minute, after pressure from sponsors, including, on one occasion, Coca-Cola. When he did contribute, papers he gave attacking sugar were omitted from publications. The British Nutrition Foundation, one of whose sponsors was Tate & Lyle, never invited anyone from Yudkin’s internationally acclaimed department to sit on its committees. Even Queen Elizabeth College reneged on a promise to allow the professor to use its research facilities when he retired in 1970 (to write Pure, White and Deadly). Only after a letter from Yudkin’s solicitor was he offered a small room in a separate building.

“Can you wonder that one sometimes becomes quite despondent about whether it is worthwhile trying to do scientific research in matters of health?” he wrote. “The results may be of great importance in helping people to avoid disease, but you then find they are being misled by propaganda designed to support commercial interests in a way you thought only existed in bad B films.”

And this “propaganda” didn’t just affect Yudkin. By the end of the Seventies, he had been so discredited that few scientists dared publish anything negative about sugar for fear of being similarly attacked. As a result, the low-fat industry, with its products laden with sugar, boomed.

Yudkin’s detractors had one trump card: his evidence often relied on observations, rather than on explanations, of rising obesity, heart disease and diabetes rates. “He could tell you these things were happening but not why, or at least not in a scientifically acceptable way,” says David Gillespie, author of the bestselling Sweet Poison. “Three or four of the hormones that would explain his theories had not been discovered.”

“Yudkin knew a lot more data was needed to support his theories, but what’s important about his book is its historical significance,” says Lustig. “It helps us understand how a concept can be bastardised by dark forces of industry.”

From the Eighties onwards, several discoveries gave new credence to Yudkin’s theories. Researchers found fructose, one of the two main carbohydrates in refined sugar, is primarily metabolised by the liver; while glucose (found in starchy food like bread and potatoes) is metabolised by all cells. This means consuming excessive fructose puts extra strain on the liver, which then converts fructose to fat. This induces a condition known as insulin resistance, or metabolic syndrome, which doctors now generally acknowledge to be the major risk factor for heart disease, diabetes and obesity, as well as a possible factor for many cancers. Yudkin’s son, Michael, a former professor of biochemistry at Oxford, says his father was never bitter about the way he was treated, but, “he was hurt personally”.

“More than that,” says Michael, “he was such an enthusiast of public health, it saddened him to see damage being done to us all, because of vested interests in the food industry.”

One of the problems with the anti-sugar message – then and now – is how depressing it is. The substance is so much part of our culture, that to be told buying children an ice cream may be tantamount to poisoning them, is most unwelcome. But Yudkin, who grew up in dire poverty in east London and went on to win a scholarship toCambridge, was no killjoy. “He didn’t ban sugar from his house, and certainly didn’t deprive his grandchildren of ice cream or cake,” recalls his granddaughter, Ruth, a psychotherapist. “He was hugely fun-loving and would never have wanted to be deprived of a pleasure, partly, perhaps, because he grew up in poverty and had worked so hard to escape that level of deprivation.”

“My father certainly wasn’t fanatical,” adds Michael. “If he was invited to tea and offered cake, he’d accept it. But at home, it’s easy to say no to sugar in your tea. He believed if you educated the public to avoid sugar, they’d understand that.”

Thanks to Lustig and the rehabilitation of Yudkin’s reputation, Penguin republished Pure, White and Deadly 18 months ago. Obesity rates in the UK are now 10 times what they were when it was first published and the amount of sugar we eat has increased 31.5 per cent since 1990 (thanks to all the “invisible” sugar in everything from processed food and orange juice to coleslaw and yogurt). The number of diabetics in the world has nearly trebled. The numbers dying of heart disease has decreased, thanks to improved drugs, but the number living with the disease is growing steadily.

Related: Why are we fatter than ever?

As a result, the World Health Organisation is set to recommend a cut in the amount of sugar in our diets from 22 teaspoons per day to almost half that. But its director-general, Margaret Chan, has warned that, while it might be on the back foot at last, the sugar industry remains a formidable adversary, determined to safeguard its market position.

Recently, UK food campaigners have complained that they’re being shunned by ministers who are more than willing to take meetings with representatives from the food industry. “It is not just Big Tobacco any more,” Chan said last year. “Public health must also contend with Big Food, Big Soda and Big Alcohol. All of these industries fear regulation and protect themselves by using the same tactics. They include front groups, lobbies, promises of self-regulation, lawsuits and industry-funded research that confuses the evidence and keeps the public in doubt.”

Dr Julian Cooper, head of research at AB Sugar, insists the increase in the incidence of obesity in Britain is a result of, “a range of complex factors”. “Reviews of the body of scientific evidence by expert committees have concluded that consuming sugar as part of a balanced diet does not induce lifestyle diseases such as diabetes and heart disease,” he says.

If you look up Robert Lustig on Wikipedia, nearly two-thirds of the studies cited there to repudiate Lustig’s views were funded by Coca-Cola. But Gillespie believes the message is getting through. “More people are avoiding sugar, and when this happens companies adjust what they’re selling,” he says. It’s just a shame, he adds, that a warning that could have been taken on board 40 years ago went unheeded: “Science took a disastrous detour in ignoring Yudkin. It was to the detriment of the health of millions.”

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