Why fructose sugar makes us sick

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In 1972, British physiologist, nutritionist and physician John Yudkin summarized years of research on the dangers of eating too much sugar in his book Pure, White and Deadly. Julia Llewellyn Smith's recent article, "The man who tried to warn us about sugar," details how the sugar industry ruined Yudkin's scientific reputation, led scientists astray, and postponed action by health authorities for decades.

With sugar overconsumption now firmly established as a major cause of obesity, diabetes and heart disease, Yudkin is seen as a prophet. But in the 1970s, an opposing theory was that saturated fats were the primary cause of heart disease. Its leading proponent, University of Minnesota epidemiologist Ancel Keys, engaged in a highly personal attack on Yudkin in the scientific literature: "Yudkin has no theoretical basis or experimental evidence to support his claim… [it] is disproved by many studies superior in methodology and/or magnitude to his own."

Robert Lustig, Professor of Pediatrics at the University of California, San Francisco, and an expert on childhood obesity, writes in the introduction to a new version of Pure, White and Deadly: "The Pharisees of this nutritional holy war declared Keys the victor, Yudkin a heretic and a zealot, threw the now discredited Yudkin under the proverbial bus, and relegated his pivotal work to the dustbin of history."

So, fat became the culprit. The food industry was quick to come out with a wide range of "low-fat" products. Consumers were told these products were healthy -- even when laced with sugar. And the cost of adding sugar to other foods declined significantly after some clever Japanese chemical engineers developed an enzyme-driven process to transform corn into high-fructose corn syrup. 

Fructose -- the sweetest of the natural sugars, found in fruits -- is now produced in huge amounts and added to a wide range of processed foods and drinks. According to United States Department of Agriculture statistics, Americans now consume a staggering 10 million tonnes of high-fructose corn syrup annually, mostly in sweetened beverages. Average individual consumption of corn syrup increased from 0.5 pounds per year in 1970 to 43.5 pounds per year in 2010. 

On March 5, 2014, the World Health Organization (WHO) launched a consultation on a new draft guideline on sugar intake. In 2002, WHO recommended that sugars comprise no more than 10 per cent of dietary calories. It now proposes that sugar intake be reduced to 5 per cent of total calories: about 25 grams, or 6 teaspoons per day for an average adult. WHO points out that "A single can of sugar-sweetened soda contains up to 40 grams (around 10 teaspoons) of sugar."

A March 11, 2014 article in the journal Nature, "Storm brewing over WHO sugar proposal: Industry backlash expected over suggested cut in intake," points out that the US Sugar Association, a Washington-based lobby group, pressured the U.S. government to defund the WHO after it issued its 10 per cent sugar guideline in 2002. Average Americans of all ages still exceed this guideline. Sugar currently comprises over 15 per cent of the dietary calories of children aged 2-19.

The sugar industry may come out swinging against the new WHO proposal -- but will anyone else care?

Many health researchers care. They are sounding alarms about soaring rates of "metabolic syndrome" -- a complex disorder characterized by weight gain, insulin resistance, high levels of triglyceride fats in the bloodstream, and hypertension. Sugar intake is strongly linked to metabolic syndrome, and also to the sudden emergence of "nonalcoholic fatty liver disease" (NAFLD). Before the 1980s, chronic liver disease was mostly seen in alcoholics. Now, NAFLD symptoms such as excess fat deposition and scarring in the liver are common in overweight individuals, and have been described in children as young as 3 years old. The end result may be liver failure or liver cancer. 

Thousands of studies now point to fructose -- not dietary fat -- as the main culprit in these diseases.

Former Harvard Medical School professor Lewis Cantley, in a 2014 interview entitled "Cancer, metabolism, fructose, artificial sweeteners, and going cold turkey on sugar," answers the question, "If we're just eating too much carbohydrate generally, does it really matter whether it's fructose or any other kind?" Cantley explains why it does.   Starches and other complex carbohydrates are largely converted to glucose, which is then used by the brain and muscle cells. In contrast, sugar is 50 per cent fructose. Fructose is taken up by the liver and converted to fat, which accumulates in various parts of your body. Cantley says fructose "doesn't actually supply any energy to your brain at all, it doesn't supply any energy to your muscle; it only gets stored as fat."   

One wonders why the body would have evolved to handle fructose this way. Cantley explains:

"We have a symbiotic relationship with plants. Plants want to spread their seeds around, so they surround them with fructose. High-fructose material surrounding the seeds gets us and other animals to eat them and this craving of fructose makes us eat them a lot and we end up carrying their seeds around and spreading them. But at the same time, it gives us an advantage because those fruits ripen just at the end of the growing season, which generally means, in almost all environments, that you're not going to have much to eat over the next few months. So the best way to survive is to convert everything you eat at that time into fat. That is the long-term storage mechanism that allows you to survive until the next growing season. That's why fructose was spectacular for us 10,000 years ago, getting us through these famines that we faced every year. But today we don't have famines and so we just get fat."

John Yudkin tried to warn us over 40 years ago. As Robert Lustig says in his introduction to Pure, White and Deadly, "Yudkin correctly fingered the sugar and food industry for what they were, and still are." Lustig calls Yudkin a scientific "giant" who foresaw what a problem sugar was, even "before the advent of high-fructose corn syrup and the two-litre bottle."

Ole Hendrickson is a forest ecologist and current president of the Ottawa River Institute, a non-profit charitable organization based in the Ottawa Valley.

Photo: Laura Taylor/flickr

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