John Yudkin, Linus Pauling and the Sugar Question

“In my book I say you shouldn’t eat sweet desserts, but I also quote a professor who says that this doesn’t mean that if your hostess has made this wonderful dessert you should turn it down.  My wife used to say I always looked for that hostess.“

-Linus Pauling, 1987.

Linus Pauling and John Yudkin shared a semisweet bond that was nearly equal parts contradiction, respect and humor, and which lasted from the mid-1970s until Pauling’s death in 1994. The two men held radically different views on a number of topics including the effects of vitamins, especially vitamin C, but shared an identical view on the dangers of sugar. Indeed, Yudkin’s claims in his 1976 book This Nutrition Business that Pauling’s beliefs about vitamin C were completely incorrect did not deter Pauling from citing Yudkin’s work on sugar in a favorable light in How to Live Longer and Feel Better, published ten years later.

John Yudkin was born in London in 1910, earned a degree in chemistry and a Ph. D in biochemistry, and later studied medicine in London. As the Chair of Physiology at London University at Queen Elizabeth College, he persuaded the university to institute a Department of Nutrition in 1954, the first department in Europe devoted to undergraduate and postgraduate teaching and research in nutrition. In 1954 Yudkin became the Chair of Nutrition for Queen Elizabeth College. In the 1960s, he grew increasingly concerned with the role of nutrition in western afflictions like obesity and diabetes, and spoke of the problem of “the malnutrition of affluence.” Yudkin retired from Queen Elizabeth College in 1971, and became Emeritus Professor of Nutrition.

Pauling first commented on Yudkin’s work – chiefly his book Sugar: Sweet and Dangerous – in a 1972 article for the newsletter Executive Health. In it, Pauling summarized Yudkin’s belief that sugar is an important cause of coronary heart disease, and that saturated fat and cholesterol are not. He also described a study carried out by Yudkin in 1957, in which the death rate from coronary disease in fifteen countries was correlated in relation to the average intake of sugar. The study concluded that men consuming relatively large amounts of sucrose faced far greater odds of developing heart disease in the age range of 45 to 65, than did those who did not ingest as much sucrose. Pauling agreed with Yudkin’s findings that sugar not only provided “empty calories,” but also contributed to various diseases.

In 1976 Pauling received a copy of Chapter 12 of Yudkin’s book, This Nutrition Business, in the mail.  In this chapter, titled “What You Can Expect from Vitamins,” Yudkin stated that Pauling’s claims about vitamin C were untrue. Yudkin suggested that the human body needs a certain amount of vitamins and no more, and that to ingest more vitamins than are required is a waste – thinking that was common at the time. He added that he knew Pauling personally and thought of him as warm and friendly, but also that “I think sincerely that he is wrong in most of what he says about vitamin C and about the use in large amounts of this and other vitamins in the preservation of health and in the treatment of disease.”

He then proceeded to find fault in Pauling’s argument that the best diet is one of raw fruits and vegetables; a diet that would provide roughly the same amounts of vitamin C that humans consumed millions of years ago. Yudkin instead argued that humans have subsisted on an omnivorous diet for at least two million years, and that if they really weren’t ingesting enough vitamin C they would have died off long ago.

The year after Yudkin wrote about Pauling in his book, Pauling – in what may have been a retaliation of sorts – singled out Yudkin as an example of subjective reporting on nutrition.  Pauling mailed his editorial “Needed: More Responsibility, More Objectivity, Less Bias,” to Yudkin along with a short note telling him that he was sorry to have to use him as an example, and that he hoped Yudkin would “get around to examining the evidence about nutrition in relation to disease in an unbiased and responsible way sooner or later.” Yudkin answered Pauling with a terse note informing him that his views were simply different, and that Pauling should not accuse people of being biased and irresponsible just because they had differences of opinion.

It was clear by 1986 that all was forgiven, when Pauling cited Yudkin extensively in his book How to Live Longer and Feel Better.  In Chapter 6, Pauling discussed Yudkin’s book Sugar: Sweet and Dangerous, in which Yudkin demonstrated that ingesting sucrose leads to coronary disease. According to Pauling,

Against the general public acceptance of the proposition that coronary heart disease is caused by a high intake of animal fat (saturated fat) and the eating of foods containing cholesterol, Yudkin himself has shown that for some countries the correlation of coronary disease with intake of sugar is much better than that with intake of fat.

Pauling later commented that “It has been shown in a trustworthy clinical study that the ingestion of sucrose leads to an increase in the cholesterol concentration in the blood.” The trustworthy study of which he speaks was reported by Milton Winitz along with his associates in 1964 and 1970. This investigation studied eighteen prisoners who had volunteered to be locked into an institution for about six months and have their cholesterol levels recorded as they were fed a specific diet. After a preliminary period, the group was placed on a small-molecule diet made up of seventeen amino acids, a little fat, vitamins, essential minerals, and glucose.  From there, more sucrose was added back into the diet.  During the length of the study, the group’s cholesterol levels were closely monitored.

The average cholesterol concentration during the initial period, during which the subjects had been fed a standard Western diet, had been 227 milligrams per deciliter. After two weeks on the glucose diet, the average concentration dropped to 173 and, two weeks later, to 160. After that point, a quarter of the glucose in the subjects’ diet was replaced by sucrose. In a week the average cholesterol concentration was 178, and two weeks later it had risen to 208. The glucose was then added back into the diet, replacing the sucrose, and results were evident in one week, when the average cholesterol concentration dropped to 175, and kept dropping afterward to points even lower than the 160 initially recorded. In his book, Pauling stated that this study “shows conclusively that an increased intake of sucrose leads to an increased level of blood cholesterol.”

At the end of Chapter 6, Pauling concurs with Yudkin and gives advice to the reader regarding sugar. His first admonition is to keep away from the sugar bowl – to keep it out of your coffee or tea. He also warns against prepared, frosted breakfast cereals, and to keep away from any regular intake of sweet desserts. His last piece of advice is to avoid soft drinks. In a different section of the book, Pauling advises, as part of a regimen for better health, to “keep your intake of ordinary sugar (sucrose, raw sugar, brown sugar, honey) to 50 pounds per year, which is half the present U.S. average.” (By 2003, Americans were consuming 142 pounds per year, on average.)

In December 1987, Pauling was interviewed for the magazine Outside for an article that focused specifically on his views on sugar. In it, Pauling is quoted as saying, “the increasing incidence of [coronary] disease closely parallels the increasing consumption of sugar. It is not at all correlated with the consumption of animal fat (saturated fat) or of total fat.” With this, Pauling reaffirmed his support for Yudkin’s viewpoint that sucrose is the primary culprit behind cardiovascular disease.

In 1989 Yudkin visited Pauling in person and, shortly thereafter, sent to Pauling a copy of his latest book Pure, White and Deadly. In thanking Yudkin for the book, Pauling asked if he would be willing to serves as a member of the Board of Associates of the Linus Pauling Institute of Science and Medicine. He also asked for a biographical sketch to be run in the Institute’s newsletter, and likewise asked for permission to reprint parts of the book in the publication.

Yudkin eventually agreed to join the Board of Associates (once assured by Pauling that his joining would not involve any work, since he had too much already) and provided a biographical sketch along with a letter in which he joked that he had “excluded such interesting aspects of my life as what clothes I wear, what I have for breakfast…”  Little bits of humor such as these dot the correspondence between the two men, who maintained a friendly relationship despite their occasional public disputes.

In a memo relaying news of Yudkin’s appointment to the Board, Pauling noted that “[i]t was Yudkin’s work that caused me to make my strong recommendations about decreasing the intake of sucrose.” Pauling also obtained copies of Pure, White and Deadly to distribute to members of the Institute, and continued to promote the book in the LPISM newsletter. Clearly, although Yudkin contradicted Pauling’s strong arguments in support of vitamin C, Pauling saw the logic in Yudkin’s case against sugar and stood firmly behind it.

Is Sugar a Poison?

[Ed Note: This is part one of a two part investigation into contemporary thinking on sugar.  Today's post focuses on recent discussions while part two will provide Linus Pauling's perspective as well as that of an important contemporary.]

After watching Robert Lustig’s lecture “Sugar: The Bitter Truth,” posted on YouTube in July 2009, viewers are sure to sympathize more with their livers, and with Lustig’s persuasive evidence that sugar is a toxin. Robert H. Lustig, M.D., is a professor of Pediatrics in the Division of Endocrinology at the University of California, San Francisco, School of Medicine, who, over the course of a 90-minute discussion on fructose, glucose and the body’s reaction to them, aims to convince the public that sugar is not just bad for us, it is toxic.

Lustig begins his engaging lecture by arguing that the reason why Americans are getting fatter is because our bodies aren’t telling us when we’re full. The hormone leptin, which signals satiety, must be malfunctioning, he says, because now we’re just eating more food. It is true that portion sizes used to be smaller, he admits, but food was just as available twenty years ago as it is now. Fat isn’t the culprit either, because we eat fewer calories from fat now than we did in the 1980s, yet obesity is still rising.

One component of the problem is what Lustig calls the “Coca-Cola Conspiracy”: Coca-Cola has become saltier, which makes you thirsty, but the salt is masked by added sugar, so the taste buds do not detect extra salt. Likewise, more caffeine has been added, providing energy but also working as a diuretic.  As a result of the added caffeine and salt, you are actually thirstier when you finish the Coca-Cola than when you started it, making you want more Coca-Cola. In the process, of course, you consume more sugar.

Robert Lustig being inteviewed by ABC News correspondent John Donvan. Credit: UC-San Francisco.

Sugar is bad, but the main crux of Lustig’s argument is that fructose in particular is a poison. Sucrose, or table sugar, is made up of 50 percent fructose and 50 percent glucose; the glucose is metabolized by every cell in the body, while the fructose is metabolized solely by the liver. High-fructose corn syrup, or H.F.C.S., is made up of 55 percent fructose and 45 percent glucose. Lustig, however, makes no distinction between sucrose and H.F.C.S., saying that both should be included in the discussion about sugar since both are processed by the body the same way.

According to Lustig, President Richard Nixon’s 1973 campaign to decrease the price of food is partly to blame for spurring the advent and popularity of H.F.C.S.  For one, H.F.C.S. is both cheaper and sweeter than sucrose, so manufacturers eventually used it more than sugar, advertising it as the healthy, natural alternative. What added to the problem, Lustig says, was the campaign by the U.S. Department of Agriculture, the American Medical Association and the American Heart Association in 1972 to cut down on fat in the American diet. This effectively diminished the amounts of fat that we ate, but did not solve the problem: “The fat’s going down, the sugar’s going up, and we’re all getting sick.” In Lustig’s view, it became apparent rather quickly that a low-fat, high-carb diet tasted like “crap,” so sugar was added to make it more palatable to the consumer’s tastebuds.

Lustig spends about fifteen minutes of his presentation giving a biochemistry lesson demonstrating that glucose and fructose are not the same thing, and also showing all the adverse physiological effects of fructose. From there, he returns to the claim made at the beginning of his lecture, which is that Americans are gaining weight because we don’t feel full. The problem with fructose, says Lustig, is that it does not stimulate insulin, and if the insulin levels do not rise, leptin is not activated, thus your brain does not receive the message that you are full. On the contrary, thanks to the unresponsiveness of the insulin, the brain receives the message that the body is starving.

Adding to the “evil” of fructose is its similarity to ethanol. Ethanol is just fermented sugar, and fructose is “ethanol without the buzz,” as Lustig puts it. The only difference, according to Lustig, is that ethanol is metabolized by the brain, causing central nervous system depression, hypothermia, hypoglycemia and loss of fine motor control, to name a few adverse effects. Fructose, on the other hand, is not metabolized by the brain at all. Further, ethanol is regulated by the government because it is considered a toxin, while sugar is not seen as dangerous. Yet, according to Lustig, chronic sugar exposure causes conditions such as hypertension, myocardial infarction, obesity, fetal insulin resistance and other assorted health problems. Fructose and ethanol are metabolized the same way by the body, but it is chronic exposure to fructose that leads to adverse effects, while with ethanol, the effects are more immediately apparent.

So what is the solution to obesity? Lustig, who treats obese children, prescribes four aspects of “lifestyle intervention” that work: a diet containing carbohydrates with fiber; no sugared beverages; following the “Paleolithic diet,” which contains mostly raw foods and no grains; and exercise.

---

Journalist Gary Taubes provides more insight on Lustig’s lecture in his New York Times article “Is Sugar Toxic?” published on April 13, 2011. Taubes has spent much of the last decade conducting journalistic research on diet and chronic diseases, and agrees with Lustig, noting, “[i]f I didn’t buy this argument myself, I wouldn’t be writing about it here.” Taubes agrees with Lustig that the problem with sugar lies not with the calories that it contains, but with the way our bodies metabolize the fructose.

According to Taubes, in an experiment involving laboratory rats and mice, it was found that if enough fructose hit the liver quickly enough, the liver would convert most of it to fat. He reiterates Lustig’s conclusion that this process eventually results in insulin resistance, which is the fundamental problem in obesity and the underlying defect in heart disease and Type 2 diabetes. However, Taubes says, the Institute of Medicine published a report in 2005 which “acknowledged that plenty of evidence suggested that sugar could increase the risk of heart disease and diabetes…but did not consider the research to be definitive. There was enough ambiguity…that they couldn’t even set an upper limit on how much sugar constitutes too much.”

Gary Taubes

Taubes next discusses the correlation between sugar consumption and diabetes: in 1980, roughly one in seven Americans was obese while almost six million were diabetic. By the early 2000s, a third of Americans were obese, while fourteen million were diabetic. On the basis of this evidence, Taubes says, it is easy to blame the over-consumption of sucrose and H.F.C.S. for the increase in health problems, since peak times of sugar consumption often correlate with spikes in obesity and diabetes.

Sugar is also likely to cause heart disease, although Taubes acknowledges that it is usually dietary fat that is blamed. He notes that in most cases where evidence was presented that indicated dietary fat was a culprit in heart disease, sugar was ignored, even though sugar consumption could also have been a factor. For example, in the 1960s Elliott Joslin, a leading authority on diabetes, claimed that sugar did not cause diabetes because the Japanese ate lots of rice, which is mostly a carbohydrate, like sugar, and there are very few diabetics in Japan. However, he did not take into account that the Japanese also ate much less table sugar than did Americans and, as Taubes brings to our attention, he did not know that rice and sugar are metabolized differently by the body.

Taubes comments that the last time an academic claimed that sugar was a toxin was in the 1970s, when John Yudkin, an authority on nutrition in the United Kingdom and a colleague of Linus Pauling, published a book about sugar called Sweet and Dangerous. In it, Yudkin recounts a series of experiments that he conducted in which sugar and starch were fed to rodents, chickens, rabbits, pigs and college students. The trials found that sugar raised the blood levels of triglycerides, which is a risk factor for heart disease. Sugar also raised insulin levels, linking it to type 2 diabetes.

At the time Yudkin’s conclusions were criticized and his work was not taken seriously. By extension, other researchers who disparaged sucrose were often compared to Yudkin and dismissed. However, according to Taubes, in recent years “physicians and medical authorities came to accept the idea that a condition known as metabolic syndrome is a major, if not the major, risk factor for heart disease and diabetes.” Metabolic syndrome is a state in which the cells in one’s body actively ignore insulin, which happens when the pancreas becomes exhausted from pumping out insulin in response to rising blood sugar levels; in some cases, rising blood sugar levels result in diabetes. Other results of chronically elevated insulin levels are heart disease, higher triglyceride levels and blood pressure, and lower levels of HDL cholesterol, which makes the insulin resistance worse. This cycle is known as metabolic syndrome.

So, Taubes asks, what causes the initial insulin resistance? His answer is that “researchers who study the mechanisms of insulin resistance now think that a likely cause is the accumulation of fat in the liver.” Fatty livers are caused by genetic disposition, eating fatty foods, and by consuming fructose, since the liver converts fructose directly to fat if it is hit with a large amount all at once. Fructose is a “chronic toxin,” meaning that it is “not toxic after one meal, but after 1,000 meals.” As a result, conclusive evidence linking fructose to fatty livers will not be forthcoming until long-term studies are conducted.  And, according to Taubes, at this point no studies have been planned that span longer amounts of time.

Finally, Taubes discusses cancer’s link to metabolic syndrome and diabetes, saying, “you are more likely to get cancer if you’re obese or diabetic than if you’re not, and you’re more likely to get cancer if you have metabolic syndrome than if you don’t.” Both metabolic syndrome and diabetes are linked to the Western diet, and countries that do not follow the Western diet experience much lower rates of cancer. One population cited by Taubes are the Inuit in the Arctic, among whom breast cancer rates were almost non-existent until the 1980s. The connection given by cancer researches, Taubes says, is that insulin resistance leads to the secretion of more insulin, and insulin promotes tumor growth.

Taubes ends his article with the statement, “Sugar scares me…I’d like to eat it in moderation. I’d certainly like my two sons to be able to eat it in moderation, to not overconsume it, but I don’t actually know what that means, and I’ve been reporting on this subject and studying it for more than a decade.” Together, Lustig and Taubes paint a dreary picture of the world’s health if it continues to consume fructose: obesity, diabetes, heart disease, and metabolic syndrome are the tangible consequences of the Western lifestyle, with Lustig’s explanation and Taubes’s analysis backing the claim that sugar is toxic.