Science can’t prove it and the industry denies it, but Gary Taubes is convinced that the sweet stuff kills.

I hope that when you have read this book I shall have convinced you that sugar is really dangerous,” wrote John Yudkin in his foghorn-sounding treatise on nutrition from 1972, Pure, White and Deadly. Sugar’s rapid rise to prominence in the Western diet, starting in the mid-19th century, had coincided with a sudden outbreak of heart disease, diabetes, and obesity. Yudkin, one of the United Kingdom’s most prominent nutritionists at the time, believed that one had caused the other.

Then, as now, there was no decisive test of his idea—no perfect way to make the case that sugar kills. It’s practically impossible to run randomized, controlled experiments on human diets over many years, so the brief against sugar, like the case against any other single foodstuff, must be drawn from less reliable forms of testimony: long-term correlations, animal experiments, evolutionary claims, and expert judgments. In Pure, White and Deadly, Yudkin offered all of these as “circumstantial evidence rather than absolute proof” of his assertion. But so many suspicious facts had already accumulated by 1972, he claimed, that it would be foolish to ignore them. Even based on circumstantial evidence, readers should be convinced “beyond reasonable doubt” of sugar’s crime against humanity.

The story of what happened next may be familiar, not just in its particulars but in the broader pattern that it represents. In the 1970s, Yudkin’s enemies, chief among them the influential American nutritionist Ancel Keys, ridiculed and buried his idea. On the basis of research sponsored by the sugar industry, Keys and others created and enshrined a different dietary bogeyman as the source of heart disease and other chronic ills: not sugar, but saturated fat. Yudkin’s book went out of print. Low-fat diets went mainstream. Sugar got a pass.

Now Yudkin’s case has been reopened. In the past few years, the dangers of dietary fat have begun to look as though they were overstated, and the risks of sugar underplayed. Among the leading advocates for this reappraisal is Gary Taubes, an investigative journalist who has been reporting on nutrition since the late 1990s. His third book on the topic of diet and health, The Case Against Sugar, is a prosecutor’s brief, much like Yudkin’s own, but fleshed out with four decades’ worth of extra science and a deeper look at both the history of that science and the commercial, economic, and political forces that helped shape it.

 

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Now Yudkin’s case has been reopened. In the past few years, the dangers of dietary fat have begun to look as though they were overstated, and the risks of sugar underplayed. Among the leading advocates for this reappraisal is Gary Taubes, an investigative journalist who has been reporting on nutrition since the late 1990s. His third book on the topic of diet and health, The Case Against Sugar, is a prosecutor’s brief, much like Yudkin’s own, but fleshed out with four decades’ worth of extra science and a deeper look at both the history of that science and the commercial, economic, and political forces that helped shape it.

How might we explain the soaring rates of heart disease, diabetes, and obesity, not to mention lots of other ailments of modernity—asthma, gout, cancer, stroke, hypertension, and maybe even dementia? These conditions tend to show up together, both in populations and in individuals, Taubes explains. “The detectives assigned to the case would start from the assumption that there was one prime suspect, one likely perpetrator, because the crimes … are so closely related,” he writes. “We should begin with the simplest possible hypothesis, and only if that can’t explain what we observe should we consider more complicated explanations.” It’s the lone-gunman theory of disease, and sugar once more stands accused.

Taubes builds his case through lawyerly layering of rich detail. A résumé of several centuries’ worth of research starts with Thomas Willis, the English doctor in the 1600s who noted that a diabetic’s urine tastes “wonderfully sweet like sugar or hon[e]y.” (Thus Willis’s decision to append the term mellitus, meaning “from honey,” to the name of the disease.) Even way back then, Willis saw fit to warn against too much sugar in the diet, but Taubes reveals that this early version of the Yudkin claim would soon be rebutted by a proto–Ancel Keys, the physician Frederick Slare.

 

A persistent back-and-forth ensued over sugar’s value as a nutrient. By the early 20th century, some experts were saying that sugar fattens us with empty calories. Others claimed it had a “much-needed stimulating effect” that might even give an edge to athletes. (“Chocolate bars for marathon runners and sugared tea for football players may result in new records,” promised one renowned diabetes researcher in 1925.) Still others argued that sugar might be poisonous. Research papers piled up.

There is no perfect way to make the case that sugar kills.

By the late 1960s, Taubes says, the most important voice defending sugar was a scientist named Fredrick Stare. Nota bene: This was not Frederick Slare, the 17th-century physician who quarreled with Thomas Willis. Stare was the 20th-century founder of the Department of Nutrition at Harvard University. Given Taubes’s blizzard of citations, such confusions are inevitable. The reader must likewise learn to discriminate among the work of Willoughby Gardner and Wightman Garner, Harold Higgins and Harold Himsworth, Gustav von Bergmann and Carl von Noorden, and that of many other homonymic experts in nutrition whose theories either rhymed or clashed. This bewilderment of names reflects, in a way, the perplexity of the scientists themselves, who seesawed for generations between rival explanations for disease, and even rival understandings of the same basic sets of facts.

In Taubes’s telling, the controversy came to a head in the mid-20th century, when prejudice and politics worked in concert to tip the scales against the anti-sugar theorists. In part, he argues, the problem stemmed from a long-standing tendency among experts to choose the most obvious answer to any given research question, and then refuse to let it go. But Taubes considers the opposite impulse, also commonly indulged, to be even more misleading: to overcomplicate the science with elaborate claims and multicausal explanations.

Nutritionists have for decades tried to disentangle a dense thicket of associations. Where the modern Western diet and lifestyle prevail, obesity, diabetes, and heart disease are correlated in the population, along with other illnesses such as cancer, gout, and hypertension. All seem related to a Western diet high in fat and sugar. The mainstream view among experts, at least in the United States, has for a long time held that the causal arrow starts with obesity. First, eating too much and exercising too little makes a person fat. Then, being fat helps to spawn illnesses like heart disease and diabetes. Meanwhile, the consumption of specific ingredients has been implicated in certain undesired states: saturated fat in heart disease, salt in hypertension, eggs in high cholesterol, red meat in gout, and so on.

According to Taubes, and the mostly European researchers whom he champions, these accounts are far too subtle. All of these Western ailments appear to be related to one another, and they’ve followed major changes in our diet. Should we really start with the assumption that this diet happens to contain not one but four or five different toxic substances, and that these toxic substances happen to produce an overlapping pattern of disease? He suggests that we proceed from a simpler premise—namely, that these conditions share one cause.

By mid-century, an emerging line of research hinted that the malefactor might be sugar. Under healthy, normal circumstances, the body secretes insulin in order to maintain stable levels of blood sugar and fat. Having too many carbohydrates in the diet—and too much sugar in particular—seems to overtax this system, messing with our metabolism and making insulin less efficient at its job. The case against sugar holds that this condition in turn can make us fat, and also diabetic, and prone to heart disease, cancer, gout, and the rest.

In other words, toxic sugar would seem to offer the most parsimonious explanation of the facts. Yet for more than 40 years, Taubes says, scientists have preferred to conjure up a broad array of factors: not only saturated fat, cholesterol, and salt, but also portion sizes, processed food, sleeping habits, lack of exercise, environmental toxins, viruses, prescription drugs, and even alterations to our microbiome. Indeed, they’ve viewed the baldness of the case against sugar as a sign of quackery or wishful thinking.

 

It’s deemed much more sensible, these days, to chart a fuzzy middle course. We went too far with saturated fat, so let’s not make that same mistake again. Instead of searching for a single bad ingredient, the experts now construct whole ecologies of blame: the food desert, the industrial farm, the consumer-capitalist society. (Sugar may be bad for you, but it can’t be the only thing …) One might choose to see this as humility. Taubes argues that it’s giving up.

Kevin Van Aelst

Certainly he’s tenacious. It takes some grit to pursue a simple claim through a jungle of confusing research, and even more when you consider how that simple claim was for many years ignored or denigrated by experts in the field. To explain this disrespect, Taubes delves into the history and politics of sugar. Things might have turned out differently, he says, and the Yudkin theory been given fair consideration, but for the long-term efforts of a partnership between the honchos in nutrition research and their conniving sponsors from the food industry. In Taubes’s telling, this group—which some have called the “sugar conspiracy”—worked behind the scenes to squelch the toxic-sugar theory.

 

Lots of food companies have paid for research that supported their parochial concerns.

To expose the machinations of Big Sugar, Taubes draws from internal memos, letters, and other industry records obtained by Cristin Kearns, a dentist who quit her job to scour university archives for evidence of backroom deals. Sugar companies formed a research foundation in 1943 and soon began a concerted effort, through hefty grants to scientists and seven-figure ad campaigns, to counter claims that sugar causes cavities and that diet soda might be better for your health, among other threats to the industry. It was, in effect, the Big Tobacco strategy: Amplify uncertainty about what causes what, put the skeptics on your payroll, kick the can of scientific proof ever further down the road. According to Taubes’s and Kearns’s research, some of the most important figures in the field of nutrition—Ancel Keys, for one, as well as Harvard’s Fredrick Stare—took money from Big Sugar and at the same time made a point of doubting sugar’s role in chronic illness.

Taubes’s account leaves out half the story, though, as I guess a prosecutor’s brief is wont to do. Allow me some reluctant words for the defense. It’s true that Keys, Stare, and their associates were taking sugar money, but Yudkin had his own ties to the food industry. According to David Merritt Johns, a Columbia University public-health historian who has studied the sugar/fat dispute, Yudkin took funding from Nestlé and the U.K.’s National Dairy Council, as well as from H. J. Heinz, Unilever, and other food-related businesses. He was also sponsored by the public-relations arm of the egg industry. On the first page of Pure, White and Deadly, he offers thanks to “the many firms in the food and pharmaceutical industry that for 25 years have given me such constant generous support,” claiming that “for many of them” the results of his research “were often not at all in their interests.” Johns says this sort of coziness with industry appears to have been common in the field.

As the journalist Nina Teicholz has demonstrated, lots of food companies have paid for research that supported their parochial concerns. (Vegetable-oil producers, for example, helped to prosecute the case against saturated fat through groups like the Wesson Fund for Medical Research.) “There has been a lot of bad science in the field of nutrition—and many ‘Big Tobaccos,’ ” Teicholz wrote in a recent Los Angeles Times op-ed responding to Kearns’s research. The interests arrayed behind each individual ingredient—sugar, eggs, oil, wheat, whatever—made their own attempts to influence scientific research, and in so doing helped undercut competitors and defend themselves from regulation. Some were more successful than others.

And though Taubes depicts Big Sugar as a single actor in a far-reaching and triumphant plot, history doesn’t really bear him out. By the end of the 1970s, he writes, the industry “had managed to shape both public opinion on the healthfulness of sugar, and how the public-health authorities and the federal government would perceive it for the next quarter-century, if not, perhaps, ever since.” The coup de grâce arrived in 1980, with the publication of the first edition of the U.S. government’s Dietary Guidelines for Americans. That document, heavily influenced by the work of sugar apologists, recommended cuts to total-fat and saturated-fat intake while noting that, “contrary to widespread opinion,” eating too much sugar likely does not lead to heart disease or diabetes. On the basis of this shift in expert opinion, low-fat products multiplied on supermarket shelves. Americans ate more carbohydrates and drank more sugar-sweetened sodas. The epidemic of obesity got even worse.

Taubes is a clear-eyed zealot for his cause, acknowledging his bias and pressing on for better science.

This account would make you think the case against sugar had been dropped, when in fact it never really went away. Taubes notes that in May 1976, the Public Relations Society of America gave a Silver Anvil Award to the Sugar Association for its “ability to stem the flow of reckless commentary” about sugar. But as his book also reveals, that commentary continued—showing up the very next month, for example, in The New York Times Magazine. “The Bitter Truth About Sugar,” a broadside by Jean Mayer, whom Taubes describes as “easily the most influential nutritionist in the United States,” claimed that sugar can be as addictive as tobacco and is likely responsible for dental cavities, obesity, and diabetes. “Purveyors of health foods and ‘natural foods’ enthusiasts are unanimous in their statements that white sugar is toxic,” Mayer wrote. (Fredrick Stare followed with a four-point rebuttal in a letter to the editor.)

Then, in the spring of 1977, the FDA proposed a ban on the artificial sweetener saccharin. Taubes portrays this as the culmination of Big Sugar’s scheme to protect itself from growing sales of diet soda. (The sugar interests had launched a million-dollar ad campaign against diet soda in the 1960s, and sponsored research on the link between artificial sweeteners and bladder cancer in rats.) Yet the regulators’ plan sparked a backlash from the sugar-fearing public—more than 40,000 letters to the agency by early summer. One magazine cited an estimate that the loss of saccharin might cause an extra 25,000 cases of cardiovascular disease every year. Dentists warned of an epidemic of bad teeth. Before long, Congress stepped in to prevent the ban.

Taubes asserts that the damage to the diet-soda business had been done. “Artificial sweeteners had been … irrevocably tainted,” he writes. “In the 1980s, when food-industry analysts were predicting a surge in diet-soda sales that failed to last, one explanation was that consumers continued to think of these substances as far more noxious than sugars.”

That’s not at all what happened, though. With the introduction in the early 1980s of Diet Coke—made with aspartame, a better-tasting artificial sweetener—demand for sugar-free soda took off. Bold predictions of the market’s surge were met, and then exceeded. Diet soda’s share of total soda sales climbed steadily throughout the ’80s and ’90s, even through the peak years of the low-fat craze. The market reached its ceiling only in 2007.

The truth is that even the Dietary Guidelines of 1980 were not as unreservedly sugar-friendly as Taubes portrays. Sugar, though exonerated of causing heart disease or diabetes, was charged with a lesser crime: promoting tooth decay. Under the heading “Avoid Too Much Sugar,” the Guidelines warned against the sugars and syrups in jams, jellies, candies, cookies, sodas, cakes, and pies.

I’m not trying to debunk Taubes’s anti-sugar position. As an industry consultant might say, “I’m only pointing out some inconsistencies.” These should be considered in their murky context, though. Just as the history defies a simple reading, the research on nutrition—ample and diverse though it’s been—isn’t close to dispositive. We can’t prove the case against sugar, and we can’t prove the case against that case, either. Taubes knows this as well as anyone. Though his book is an impassioned brief, it never fails to describe the scientific evidence for what it is: “suggestive,” rather than definitive, or, in other places, “compelling” and “provocative.” He’s a clear-eyed zealot for his cause, acknowledging his bias even as he presses on for better science.

It’s extraordinary and refreshing to see a science journalist so wary of his sources.

Outside of his book, Taubes is ready to admit, for example, that commercial research grants aren’t always bad for science. Industry funding is “a double-edged sword,” he told the Pittsburgh Post-Gazette in 2014; it pushes research forward, at a slant. Money from the business world helped address what he sees as another myth of healthy eating—that salt causes hypertension. Someone had to pay for scientists to study this idea, he said, and the food industry stepped up. But when these studies found that salt maybe isn’t all that bad for you, they were cast in doubt. “People say, ‘Well, look who funded the study.’ ”

For Taubes, the entire field of nutrition science—industry-funded or not—should be viewed with skepticism. “I actually think the evidence is ambiguous,” he said in a recent interview on sugar. “I mean if it was a criminal case, you would have enough to indict but not to convict because all the research has holes in it.” Much nutrition research suffers from a fatal flaw: It relies on short-term studies to examine chronic, long-term problems. His critique goes further. In a footnote to The Case Against Sugar, he writes that when he started reporting his first book on nutrition, he found to his dismay that many of the people he interviewed lacked basic knowledge about sugars. Epidemiologists and doctors weren’t even aware that fructose—the form of sugar that he believes to be most toxic—makes up half of table sugar, and that high-fructose corn syrup contains glucose. “They didn’t have the nutrition or biochemistry background necessary at the time to be aware of these simple facts.”

It’s extraordinary and refreshing to see a science journalist so wary of his sources, and so willing to present himself as someone who knows more than they do. Given all the irresolvable uncertainty, Taubes must fall back on expert judgment of the facts, and he does what few science journalists dare: He invokes not some egghead academic’s assessment, but his own. The clear subtext of The Case Against Sugar is that Taubes has done a more thorough job of accounting for the evidence than even some of the leading figures in the field. And having devoted himself so completely to a single topic, and with such depth and perspicacity, he may well be right. I’m not sure that he still counts as a journalist. It’s as though he’s fallen through a wormhole from reporting into expertise.

That crisis of identity has become only more complicated. Is Taubes a journalist, an activist, a scholar? In September 2012, he branched out from science writing and got involved with science research. With the help of a doctor and researcher named Peter Attia, he launched the Nutrition Science Initiative—a nonprofit with the stated goal of sponsoring careful, well-controlled studies on long-standing questions in the field. He set out to do his part in plugging some of those many holes in the research.

The initiative’s first study, on what happens when you eat fewer carbs while consuming the same amount of calories overall, came out this past summer. It appeared to show that the low-carb, low-sugar diet did not increase the loss of body fat in 17 men across a four-week stretch. Kevin Hall, a researcher at the National Institutes of Health and the study’s lead author, said that the results of that and another study he’d conducted “basically falsify” one theory of how sugar and other carbohydrates make us fat. Other experts have been more circumspect, saying that this was just a pilot study (and another short-term one), and that its findings are, in fact, equivocal. Taubes himself declared the results “interesting” but added, “They’re very hard to interpret.”

In other words, he hasn’t budged—at least not yet. Could sugar be responsible for a national catastrophe in public health, in which one in three adults is obese, one in seven has diabetes, and one in four or five will die of cancer? Until someone comes along and proves the opposite, Taubes considers the simplest and most likely answer to be yes. The rest of us will have to draw our own conclusions, based on information from whatever sources—doctors, gurus, journalists, or intuition—we happen to prefer.

But when all is said and done, our verdict on sugar—I mean yours and mine, not that of scientific experts—may not matter all that much. Even if we’re inclined to be suspicious, and even if we choose another villain in its place, our diets may end up more or less the same. Consider what is now among the most popular alternatives to Yudkin’s theory, espoused by Michael Pollan—the idea that processed foods, as a category, are more to blame than any one ingredient, and that we should stay away from them. As Taubes points out, these same products virtually all contain sugar, so it wouldn’t make a difference whether we’re avoiding one thing or the other. Either way, we’d get less sugar overall.

The same goes for other mainstream diets. “Whether you’re trying to avoid gluten, trans fats, saturated fats, or refined carbohydrates of all types, or just trying to cut calories—eat less and eat healthy—an end result of this advice is that you’re often avoiding processed foods containing sugar and a host of other ingredients,” Taubes writes at the end of the book. “If we benefit, we cannot say exactly why.”

This may be a source of some despair for scientists, but for the rest of us, it’s a heartening idea. The case against sugar is unresolved, and yet we know exactly what to do.