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THE DEADLY
EFFECTS OF FRUCTOSE
SUGAR IS FATTENING. This nutritional fact enjoys almost universal agreement. The 1977 Dietary Guidelines for Americans clearly warned against the dangers of excessive dietary sugar, but the message got lost in the anti-fat hysteria that followed. Dietary fat was the overwhelming concern of health- conscious shoppers, and the sugar content of food was ignored or forgotten. Bags of jellybeans and other candies were proudly proclaiming themselves to be fat free. The fact that they were virtually 100 percent sugar didn’t seem to bother anybody. Sugar consumption rose steadily from 1977 to 2000, paralleled by the rising obesity rates. Diabetes followed with a time lag of ten years.
IS SUGAR TOXIC?
THE WORST OFFENDER, by far, is the sugar-sweetened drink—soft drinks, sodas and, more recently, sweetened teas and juices. Soda is a $75 billion industry that had, until recently, seen nothing but good times. Per capita intake of sugar-sweetened drinks doubled in the 1970s. By the 1980s, sugar- sweetened drinks had become more popular than tap water. By 1998, Americans were drinking 56 gallons per year. By the year 2000, sugar- sweetened drinks provided 22 percent of the sugar found in the American diet, compared to 16 percent in 1970. No other food group even came close.1
Thereafter, sugar-sweetened drink relentlessly declined in popularity.
From 2003 to 2013, soft-drink consumption in the United States dropped by close to 20 percent.2 Sweetened iced teas and sugary sports drinks have valiantly tried to take their place, but have been unable to block the winds of change. By 2014, Coca Cola had faced nine consecutive years of sales decline as health concerns about sugar mounted. Concerned with declining health and ballooning waistlines, people were less inclined to drink a toxic, sugary brew.
Sugar-sweetened drinks now face strong political opposition—from proposed soda taxes to the recent effort by New York mayor Michael Bloomberg to outlaw oversized beverages. Some of the problems, of course, are self-inflicted. Coca Cola spent decades convincing people to drink more soda. They were wildly successful, but at what cost? As the obesity crisis grew, the companies found themselves under increasing fire from all sides.
But the sugar pushers weren’t so easily defeated. Knowing that they were fighting a losing battle in much of North America and Europe, they took aim at Asia to make up for lost profits. Asian sugar consumption is rising at almost 5 percent per year,3 even as it has stabilized or fallen in North America.
The result has been a diabetes catastrophe. In 2013, an estimated 11.6 percent of Chinese adults have type 2 diabetes, eclipsing even the long-time champion: the U.S., at 11.3 percent.4 Since 2007, 22 million Chinese were newly diagnosed with diabetes—a number close to the population of Australia.5 Things are even more shocking when you consider that only 1 percent of Chinese had type 2 diabetes in 1980.6 In a single generation, the diabetes rate rose by a horrifying 1160 percent. Sugar, more than any other refined carbohydrate, seems to be particularly fattening and leads to type 2 diabetes.
Daily consumption of sugar-sweetened drinks not only carries a significant risk of weight gain, but also increases the risk of developing diabetes by 83 percent compared to drinking less than one sugar-sweetened drink per month.7 But is the culprit sugar or calories? Further research suggested that the prevalence of diabetes rose by 1.1 percent for every extra 150 calories per person per day of sugar.8 No other food group showed any significant relationship to diabetes. Diabetes correlates with sugar, not calories.
Sucrose, against all logic and common sense, had not been considered bad for diabetics. In 1983, Dr. J. Bantle, a prominent endocrinologist, asserted in the New York Times 9 that “the message is that diabetics may eat foods containing ordinary sugar, if they keep the amount of calories at the same constant level.” The U.S. Food and Drug Administration (FDA) undertook a comprehensive review in 1986.10 Citing more than 1000 references, the Sugars Task Force declared, “there is no conclusive evidence on sugars that demonstrates a hazard.” In 1988, the FDA would reaffirm sugar as “Generally Recognized as Safe.” In 1989, the National Academy of Sciences’ report Diet and Health: Implications for Reducing Chronic Disease chimed in with the view that “sugar consumption (by those with an adequate diet) has not been established as a risk factor for any chronic disease other than dental caries in humans.”11
Yes, cavities. There seemed to be no concern that eating more sugar would raise blood sugar. Even in 2014, the American Diabetes Association website stated that “experts agree that you can substitute small amounts of sugar for other carbohydrate-containing foods into your meal plan.” 12
Why sugar is so fattening? Sugar is sometimes considered “empty calories,” containing few nutrients. It is also thought to make food more “palatable” and “rewarding,” causing overconsumption and obesity. But perhaps the fattening effect of sugar is due to its nature as a highly refined carbohydrate. It stimulates the production of insulin, which causes weight gain. But then again, most refined carbohydrates, such as rice and potatoes, do so too.
What was it specifically about sugar that seems to be particularly toxic? The INTERMAP study compared Asian and Western diets in the 1990s.13 The Chinese, despite much higher intakes of refined carbohydrates, had far lower rates of diabetes. Part of reason for this advantage lies in the fact that their sugar consumption was much lower.
Sucrose differs from other carbohydrates in one important way. The problem? Fructose.
SUGAR BASICS
GLUCOSE, A SUGAR with the basic molecular structure of a six-sided ring, can be used by virtually every cell in the body. Glucose is the main sugar found in the blood and circulates throughout the body. In the brain, it is the preferred energy source. Muscle cells will greedily import glucose from the blood for a quick energy boost. Certain cells, such as red blood cells, can only use glucose for energy. Glucose can be stored in the body in various forms such as glycogen in the liver. If glucose stores run low, the liver can make new glucose via the gluconeogenesis process (literally meaning “making new glucose”).
Fructose, a sugar with the basic molecular structure of a five-sided ring, is found naturally in fruit. It is metabolized only in the liver and does not circulate in the blood. The brain, muscles and most other tissues cannot use fructose directly for energy. Eating fructose does not appreciably change the blood glucose level. Both glucose and fructose are single sugars, or monosaccharides.
Table sugar is called sucrose, and is composed of one molecule of glucose linked to one molecule of fructose. Sucrose is 50 percent glucose and 50 percent fructose. High-fructose corn syrup is composed of 55 percent fructose and 45 percent glucose. Carbohydrates are composed of sugars. When these carbohydrates contain a single sugar (monosaccharides) or two sugars (disaccharides), they are called simple carbohydrates. When many hundreds or even thousands of sugars are linked into long chains (polysaccharides), they are called complex carbohydrates.
However, it was recognized long ago that this classification provided little physiologically useful information, since it only differentiates based upon the chain length. It had previously been thought that complex carbohydrates were digested more slowly, causing less of a rise in blood sugar, but this is not true. For example, white bread, which is composed of complex carbohydrates, causes a very quick spike in blood sugar, almost as high as a sugar-sweetened drink.
Dr. David Jenkins reclassified foods according to their blood glucose effect in the early 1980s, which provided a useful comparison of the different carbohydrates. This pioneering work led to the development of the glycemic index. Glucose was given the value of 100, and all other foods are measured against this yardstick. Bread, both whole wheat and white, has a glycemic index of 73, comparable to Coca-Cola, which has a value of 63. Peanuts, on the other hand, have a very low value of 7.
There is an unspoken assumption that most of the negative effects of carbohydrates are due to their effect on blood glucose, but this idea is not necessarily true. Fructose, for example, has an extremely low glycemic index. Furthermore, it should be noted that the glycemic index measures blood glucose, not blood insulin levels.
FRUCTOSE: THE MOST DANGEROUS SUGAR
WHERE DOES FRUCTOSE fit in? Fructose does not raise the blood glucose appreciably, yet is even more strongly linked to obesity and diabetes than glucose. From a nutritional standpoint, neither fructose nor glucose contains essential nutrients. As a sweetener, both are similar. Yet fructose seems particularly malevolent to human health.
Fructose was previously considered a benign sweetener because of its low glycemic index. Fructose is found naturally in fruits, and is the sweetest naturally occurring carbohydrate. What could be wrong with that?
The problem, as often is the case, is a matter of scale. Natural fruit consumption contributed only small amounts of fructose to our diet, in the range of 15 to 20 grams per day. Things began to change with the development of high-fructose corn syrup. Fructose consumption steadily rose until the year 2000, when it peaked at 9 percent of total calories. Adolescents in particular were heavy users of fructose at 72.8 grams per day.14
High-fructose corn syrup was developed in the 1960s as a liquid equivalent of sucrose. Sucrose was processed from sugar cane and sugar beets. While not exactly expensive, it wasn’t exactly cheap. High-fructose corn syrup, however, could be processed from the river of cheap corn