Monday, December 28, 2015

Book Review: "Pure, White and Deadly" by John Yudkin

Dr. John Yudkin (1910 - 1995) was a British scientist and medical doctor who founded a prestigious Department of Nutrition at Queen Elizabeth College in London. He was in fact a pioneer in the field, founding the first Bachelor of Science degree program in nutrition in a European university.

Yudkin became interested in the correlation he noticed between sugar (sucrose, properly) consumption and coronary thrombosis, the formation of a clot in the heart. Yudkin had already become a best-selling proponent of a low-carbohydrate diet for losing weight, and was therefore familiar with the health problems associated with the excess consumption of carbohydrates. Obesity, diabetes, and heart disease often come as a package, and in the 1960s Yudkin came to the conclusion that there was sufficient epidemiological evidence to link sugar consumption to not only obesity but to the new epidemic of coronary thrombosis.

 Epidemiology is not, as Yudkin is careful to make clear with many amusing examples, sufficient to prove a cause-and-effect relationship, so he commenced to perform many experiments over the following decades in an attempt to discern a real relationship. He then proceeded to explore other harmful effects of excess sugar in the diet, some of which are quite surprising. He goes into detail in the chapter "Eat sugar and see what happens", and among other effects the cholesterol profile took a dramatic turn for the worse, insulin rose, glucose tolerance declined, and blood pressure rose. Additionally, in support of his theory that sugar might be related to thrombosis, the platelets of humans on a high-sugar diet in the blood became more sticky (in subjects eating the amount that he'd found was typical of consumption for those who'd already suffered from thrombosis). The platelets behaved just like those in people who already had atherosclerosis, in fact.

He also makes clear that all carbohydrates are not created equal, as he found that sugar (50% glucose and 50% fructose) has far worse effects on the body than starch (100% glucose), as some of the feeding studies he and others conducted compared the effects of both.

After making a very strong case for the fundamentally damaging effects of the over-consumption of sugar, in the chapter "A host of diseases" he lists those which are reasonably thought to be caused, at least in part, by sugar consumption:

  • Damage to the eyes
  • Damage to the teeth
  • Damage to the skin
  • Damage to the joints
  • Is there a link between sugar and cancer?
  • Sugar and drug action
  • Sugar and protein
  • Sugar and indigestion

He also details the evidence that a high sugar diet leads to a substantial reduction in lifespan, on the order of from 71 to 50 years, comparing rat lifespans to human.

In an earlier chapter he'd already detailed the astounding increase—25-fold!—in sugar consumption in the wealthy countries over the previous 200 years as sugar went from being a delicacy stored in locked boxes to an ever-present food additive. It's not unusual to see children getting 50% of their daily calories from sugar in one form or another.

So it's not hard to see how it's perfectly reasonable to connect the dramatic increase in morbidity, the chronic diseases of affluence that most of us now suffer from, to this huge change in the human diet.

But Yudkin is careful throughout to explain the limits of his knowledge and experiments, and to include the contrary viewpoint, noting that many don't agree with his conclusions.  This is, of course, the mark of a true scientist: knowledge is limited, and often imperfect, and any who claim to have perfect knowledge are often frauds.

Paleo diet fans like myself will be pleased to see Yudkin explaining that a low-carb diet like those of our ancient ancestors is likely the best option:
"In nutritional terms, the diet of prehistoric human beings and their ancestors during perhaps two million year or more was rich in protein, moderately rich in fat, and usually poor in carbohydrate....
"...The effect of the Neolithic revolution was thus to alter the components of the diet so that it was now rich in carbohydrate and poor both in protein and fat.  The carbohydrate was overwhelmingly starch, with sugars supplied only to a small extent as before by wild fruits and vegetables."
Pure, White, and Deadly was originally published in 1977.  The currently available version published in 2012 is a reprint of the 1986 revision.  As such, it's a bit out-of-date on certain topics.  Yudkin nevertheless uses his evolutionary perspective to good effect:
"It may turn out in the end that people would reduce their chances of getting heart attacks if they took large quantities of polyunsaturated fats such as those found in maize (corn) oil or in sunflower-seed oil, or in the special sorts of margarines made with these oils [omega-6 fats, specifically linoleic acid].  I have to say however that I think it very unlikely that this will happen.  I believe that the best diet for the human species is one made up as far as possible of the foods that were available in our hunting and food-gathering days.  The oils rich in polyunsaturates have been available only because of recent advances in agriculture and in the even more recent elaborate industrial techniques of extracting and refining oils; the complex chemical processing of these and other oils [hydrogenating] to produce margarine removes this product even further from the sorts of foods available to humanity during millions of years of evolution."
The last chapter, "Attack is the best defense", is an account of the many attempts to silence Yudkin and his research, most at the request of the of the sugar industry, but some by other scientists such as Ancel Keyes.  Cancelling conferences, suppression of speeches he did give at conferences, refusal to fund research that might prove contrary to commercial interests, propaganda, and flat libel were among the tools used to silence his message.  This is perhaps the most disheartening part of the book, as the sugar and food companies seem to have a great deal in common with the tobacco companies, despite a few ethical individuals with open minds.  They're not the worst villains that Yudkin details, however.  One would have to reserve that title for the parents who feed their children foods that the parents know to be harmful, as almost all parents do know that sugary foods are not the best options.  The child who ate 65% of his calories as sugar and promptly rotted his teeth out was probably not buying all his food himself, and Yudkin mentions the large number of people in Britain who are entirely without teeth, even at a young age.

What comes across in this book is that Yudkin is clearly an intelligent and eminently fair man.  His message is one that those concerned with the health of themselves and their children would be well-advised to adopt.

Personally, I suffered from countless cavities and had eight teeth pulled in my sugar-eating days.  At the age of 18, I decided to finally listen to my dentist and largely eliminated sugar from my diet.  I went 20 years without another cavity, until my company installed a mint bowl in the lobby.  I got one cavity, where I held the mints against my tooth while sucking on them, and have since reverted to my largely sugar-free ways.  Like Yudkin, I'll indulge in the occasional treat, but sugar's no longer a staple.  I wish I'd read this book back before I'd ruined my eyes, as that and missing teeth are the two effects of sugar that don't seem to regress on a sugar-free diet.  The steady increase in my myopia did cease, however, and I've had the same prescription for over 25 years.

The introduction to the 2012 edition is written by Dr. Robert Lustig, a specialist in childhood obesity.  Below is his hour-long lecture, "Sugar, the Bitter Truth", in which he expands on some of the topics of Yudkin's book.
"I stumbled upon Dr. Yudkin quite by accident in 2008.  I was in Adelaide, Australia, giving a talk at the Australian Association of Clinical Biochemists on my research into the role of sugar in the pathogenesis of metabolic syndrome.  Dr. Leslie Bennett said to me, 'Surely you've read Yudkin,' and I admitted I hadn't.  When I got home, I looked for Pure, White, and Deadly, and couldn't find it in our UCSF library of in any bookstore in San Francisco.  Eventually I got it by interlibrary loan.  I opened the book, and it opened my eyes.  I already knew from my own work that sugar at our current  rate of consumption is a medical disaster.  But to learn that Yudkin foresaw what a problem sugar was thirty-six years earlier, and at a much lower dose ... was a true revelation.  Indeed, I was a Yudkin disciple and I hadn't even realized it.
Yudkin's unpopular work had been buried, as it threatened nutrition scientists' major source of funding: the packaged-food industries. Science deals harshly with its heretics, not matter how correct they are.