An interesting and insightful article in the New York Times this week (April 13, written by Gary Taubes) centered on the dangers of sugar consumption-not just for obesity and type-2 diabetes, but for a host of other endocrine diseases. On May 26, 2009, Robert Lustig gave a lecture called “Sugar, The Bitter Truth,” which was posted on YouTube the following July. It has since been viewed over 800,000 times.
Lustig is a specialist on pediatric hormone disorders and the leading expert in childhood obesity at the University of California, San Francisco, School of Medicine, arguably one of the best medical schools in the country. He makes a strong a pervasive case that sugar is a “toxin” or a “poison,” terms he uses together 13 times through the course of the lecture. By “sugar”, Lustig means not only the refined white granulated stuff we put in our coffee or on our cereal, but also high-fructose corn syrup (HFCS, of which I have written about before), calling it “The most demonized additive known to man.”
Lustig insists that sugar is not just an empty calorie, he says; its effect is much more insidious. “It’s not about the calories,” he says. “It has nothing to do with the calories. It’s a poison by itself.”
Lustig claims that sugar is not only responsible for obesity and type-2 diabetes, but also implicit in heart diseases, hypertension, and many common cancers. He says that sugar is a toxic substance that people abuse, and should be thought of , like cigarettes and alcohol, as something that’s killing us. His critics argue that he’s a zealot, but Lustig has genuine expertise, and has accumulated and synthesized a mass of evidence, which he finds compelling enough to convict sugar. The “sugar” Lustig is referring to is beet and cane sugar, whether white or brown, and HFCS, which has become “the flash point for everybody’s distrust of processed foods,” says Marion Nestle, a New York University nutritionist and the author of “Food Politics.”
A bit of history. In the early 80’s HFCS replaced sugar in sodas and other products because refined sugar had the reputation as being a noxious nutrient. HFCS was portrayed as a healthful alternative by the food industry, and the fact that it was also cheaper than sugar also helped its commercial prospects. Now the pendulum is swinging the other way, with Coke, Pepsi, and other food industry giants proudly claiming “No high-fructose corn syrup” on their labels. Lustig says, “Metabolically, there is no difference between the two-both are poisonous metabolically.
A bit of biochemistry: refined sugar (sucrose) is made up of a molecule of the carbohydrate glucose, bonded to a molecule of the carbohydrate fructose-a 50-50 mixture of the two. Fructose, which is twice as sweet as glucose, is what makes sugar different from other carbohydrate-rich foods like bread or potatoes, that break upon digestion to glucose alone. HFCS is 55% fructose, and the remaining 45% is all glucose. Because each of these sugars ends up as glucose and fructose in our guts, the physiological effects are identical. So what is it about these sugars that make them dangerous?
The fructose component of sugar and HFCS is metabolized by the liver, while the glucose from sugar and starches is metabolized by every cell in the body. Consuming sugar means more work for the liver, and if taken in sufficient quantities, and also in liquid form, fructose overwhelms the liver, and the speed with which it has to do its work affects how it will metabolize the fructose. In lab rats and mice, it’s clear that if the fructose hits the liver with quantity and speed, the liver will convert it to fat. This induces a condition called insulin resistance, a fundamental problem in obesity, type-2 diabetes, and may be an underlying defect on many cancers (cancer cells thrive in a sugar environment).
Insulin resistance begins when fat builds up in the liver; the question is what causes fat to build up in the first place? A common assumption is that getting fatter leads to a fatty liver, but what about when it happens to lean persons? Genetics? Maybe. But Lustig may also be right-it may be caused by sugar.
The question now is, how much of this stuff do we have to eat or drink, and for how long? Lustig and his colleagues at the U.C.S.F. are currently doing a study, looking a what happens when obese teenagers consume no sugar other than what they get in fruits and vegetables. Another study will do the same with pregnant women to see if their babies are born healthier and leaner.
The connection between obesity, diabetes, and cancer was first reported in 2004 in large population studies by researchers from the World Health Organization’s International Agency for Research on Cancer. There is no controversy here-you are more likely to get cancer if you are 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. This goes along with two other observations that have led to the well-accepted idea that our Western diets and lifestyles cause a large percentage of cancers. This means they could actually be prevented if we could pinpoint what the problem is and avoid or prevent that.
One observation is that death rates from cancer, like those from diabetes, increased significantly over the second half of the 19th century and the early decades of the 20th. By the 1030’s, it was apparent that age-adjusted death rates from cancer were rising in the U.S., meaning that the odds for a 60 year-old dying from cancer were increasing, even if there were more 60 year-olds.
The second observation was that diabetes and cancer rates were relatively rare in populations that didn’t eat Western diets, and in some populations it was virtually nonexistent.
Couple these observations with the fact that sugar consumption increased from less than 5 lbs per person,per year in the late 1800’s to over 150 lbs per person today. Is there a connection? You connect the dots.
Stay well, John R Blilie, M.S.