Highlights From the ‘Toxic Sugar’ Video
In case you haven’t seen it yet, there’s a video on YouTube of a lecture called “Sugar: The Bitter Truth,” delivered by Dr. Robert Lustig, a pediatric endocrinologist at the University of California, San Francisco, and one of the foremost childhood-obesity researchers in the U.S. The lecture, which runs some 90 minutes and delves into the details of the professor’s clinical observations and research, has been viewed more than a million times to date, and inspired the April 17 New York Times Magazine cover story headlined “Is Sugar Toxic?”
Lustig’s argument — in short, that sugar is poisonous to the body, not least because it increases obesity — is controversial. Many nutrition experts wouldn’t go so far as to call sugar a “toxin” or “poisonous.” But, having watched the video, I’m a convert. So, if you haven’t got time to sit through it yourself, following are five of the professor’s most thought-provoking claims.
Sugar Is Just as Unhealthy as High-Fructose Corn Syrup
Despite being singled out as a major cause of obesity and disease, high-fructose corn sryup (HFCS) is actually no different from table sugar, or sucrose, Lustig argues — and both are harmful. Both HFCS and sucrose are made of two bonded molecules: fructose and glucose. (However, added enzymes change the ratio of fructose and glucose in corn syrups — from 50/50 to 55/45, fructose to glucose.) Upon digestion, the body breaks down the bond, releasing glucose and fructose independently into our systems. Fructose is about twice as sweet as glucose, which explains why sugar is so much sweeter than other carbohydrate-rich foods like potatoes, which break down into glucose alone.
But given their identical component parts, why do we keep hearing that high-fructose corn syrup is so much worse for us than sugar? Lustig thinks it’s simply because HFCS is ubiquitous in our food supply — it’s easier to target it than regular old sugar. Corn syrup is cheap to produce, which makes is a more economical additive than refined sugar in processed foods — and, thus, it’s in everything. Most people have little idea how much HFCS they actually consume in a day, because they don’t know how far-reaching the ingredient is.
The Body Uses Glucose and Fructose Differently
Our body processes glucose more efficiently than it does fructose. Lustig explains this through a tale of two food sources: two slices of white bread versus orange juice. The bread contains 120 calories of glucose, and the juice 120 calories of sucrose.
Of the 120 glucose calories in bread, 80% (or 96 calories) will be used to fuel the body’s organs; every cell in the body uses glucose. Said Lustig, “Every living thing on the face of the earth can use glucose because glucose is the energy of life.”
The unused 20% goes to the liver, where some will be converted and stored as glycogen for later use, and some will be released into the bloodstream. That stimulates the pancreas to produce insulin, which regulates blood sugar and helps signal the brain that you are full.
Most of the stored glycogen will get burned off as your body needs it, though a very small amount — Lustig estimates half of one calorie — will be converted to low-density lipoprotein, or “bad” cholesterol. Finally, a tiny bit of the glucose leaves the liver as citrate, and through a series of processes, is turned into fat.
The sucrose from the orange juice, by contrast, is half-glucose and half-fructose — 60 calories of each. Fructose can be processed only by the liver, and cannot be used by other organs, so all 60 calories will be processed there, where it creates toxic byproducts like uric acid. High consumption of sucrose leads to high levels of uric acid, which is associated with several obesity-related diseases such gout and hypertension. In the case of hypertension, uric acid blocks the enzyme in the blood vessels that makes nitric oxide, which is what controls blood pressure. Gout is caused by a build-up of uric acid in the joints.
In his lecture, Lustig cites a University of Texas at San Antonio study of obese adolescents with hypertension; those who were given allopurinol, which treats gout, saw their blood pressure drop to normal, he said.
Why Sugar Is More Fattening Than Fat
When the low-fat diet craze erupted, companies started looking for a way to make low-fat foods still taste good — so they turned to sugar. Snackwells Creme Sandwich cookies, for example, contain just 3 grams of fat per serving, but a whopping 10 grams of sugar. Lustig suggests that such “low-fat” products are not low fat in reality, since sugar consumption contributes to the creation of more fat in the body than dietary fat or glucose.
Lustig argues that the data show that a negligible amount of the glucose we consume is converted to fat. In contrast, 30% of the fructose we eat ends up as new fat. In fact, Lustig argues, based on the effects of fructose in the body, the molecule appears to behave more like a fat than a carbohydrate. In one study of healthy medical students who spent six days on a high-fructose diet, their triglycerides and free fatty acids doubled, which caused insulin resistance and resulted in five times more fat-cell creation than when the students were not on a high-fructose diet.
Why Fiber Is Essential
Our grazing ancestors, Lustig asserts, ate an estimated 100 to 300 grams of fiber per day. Modern humans get about 12 grams. That’s because our food source is overwhelmingly refined and processed.
The problem is that while fiber consumption has dropped, intake of sucrose has gone up. In nature, high-fructose foods come in high-fiber packages: for instance, an apple has about 23 grams of fructose (more than a can of ginger ale), but it also has 4 grams of fiber (soda has none). Sugar cane itself is extremely fibrous.
So why do we need fiber with our sugar? Two essential reasons:
— Fiber slows the absorption of sugar in the gut, which limits the spikes and crashes in blood sugar that can negatively affect appetite and may over time increase a person’s risk of metabolic syndrome.
— Fiber speeds the feeling of fullness reducing the risk of overeating.
A surefire way to reduce your sugar consumption and spikes in blood sugar and insulin is to increase your fiber intake. That means more fruits, vegetables and whole grains, which nutrition experts agree are lacking in the average diet. “Fast food is fiberless food,” Lustig said.