Sugar producers are hopping mad. So are the companies that flood soft drinks, cereals, yogurts, baked goods, and various desserts with high fructose corn syrup (HFCS). There is no sweet talk at all when it comes to their reaction to a recommendation by the World Health Organization that the intake of added sugars in food and drink should be no more than 10 percent of daily calories. Sweeteners are being unfairly singled out as being responsible for poor diets, the industry claims, since the cause of obesity is too many calories, no matter where they come from. “Taxpayers’ dollars should not be used to support misguided, non-science based reports, which do not add to the health and well-being of Americans, much less to the rest of the world,” says the Sugar Association. Humbug, I say. We consume way too much sugar and other caloric sweeteners, and there is plenty of scientific information to suggest a link with obesity and other health problems. Of course the industry objects to such allegations—after all, billions of dollars are at stake.
No, sugar is not “white poison,” as some would have us believe. In moderate amounts, it can be part of a healthy diet. But North Americans are not consuming sweeteners in moderate amounts. We are guzzling them at a rate of about 50 teaspoons of added sugar per day! That is an astounding amount. It’s readily believable, though, given that a can of pop has roughly 10 spoonfuls, and many people drink several cans a day. In this context, “sugar” refers to both sucrose, which is extracted from sugar cane or sugar beets, and “high fructose corn syrup,” which is manufactured from cornstarch. Sucrose consumption has actually declined in the last twenty years, but that’s only because it has been replaced by HFCS as the prime sweetener. The increased use of HFCS mirrors the increase in obesity in North America. Of course, such an association cannot prove cause and effect, as I’m sure industry spokespeople would be quick to point out. Overconsumption of high-calorie foods and lack of exercise is the problem, they say. Technically, they are right. But the fact is that far too many of those extra calories come from added sugar. So why not reduce this? There is no downside to curbing our intake of sweeteners. There is absolutely no risk in drinking water instead of soft drinks!
Replacing sucrose with high fructose corn syrup may not be just a benign switch of one caloric sweetener for another. There may be metabolic consequences. So why was this switch made in the first place? Because HFCS costs a few pennies per kilo less than sugar does to produce. But because of the volumes used, that can translate into hundreds of millions of dollars in the long run.
The technology to produce HFCS emerged in the 1950s with the isolation of enzymes from bacteria capable of breaking cornstarch down into glucose. Since the us government subsidizes corn production, a cheap way of producing glucose now became available. There was a problem, though. Glucose is only about 70 percent as sweet as sucrose. Once more, some newly isolated enzymes entered the picture. Glucose isomerase, from a special strain of Streptomyces murinus, readily converted some of the glucose into fructose, which is 30 percent sweeter than sucrose. It is also more water soluble than glucose. This made it possible to produce a stable syrup with roughly 55 percent fructose content and high sweetening power. This “high fructose corn syrup” was easier to blend into soft drinks and foods than sucrose, and was welcomed by everyone—except, of course, the sucrose producers.
When HFCS was first introduced, nobody thought it would have a different effect on the body than sucrose. After all, sucrose is broken down in the body to equal amounts of glucose and fructose, and can therefore be thought of as a 50 percent fructose product. Can an extra 5 percent of fructose in HFCS make a metabolic difference? Yes, some researchers argue. Our consumption of fructose has increased by some 30 percent in the last thirty years, and this may have some consequences on obesity. The digestion, absorption, and metabolism of fructose differ from glucose. Fructose does not trigger insulin release, which at first may seem like a good thing. But it might not be so good. Insulin stimulates the production of a hormone called leptin, which inhibits food intake. With less leptin production, food consumption goes up. Leptin also acts on the stomach to prevent the release of ghrelin, the major hormone responsible for hunger. If there is an excess of fructose in the bloodstream, leptin is not increased, and the stomach cells are not stopped from producing ghrelin. We feel hungry, and we eat more. Furthermore, glucose itself provides satiety signals to the brain, but the transporter molecule that fructose uses to enter cells is absent from the brain. And if that isn’t enough, fructose is more readily converted into fat inside cells than glucose is.
I know what you’re thinking. Fructose is the sugar found in fruits, and everybody knows that fruit is good for us. You’re right! But an apple has only about 10 grams of fructose, whereas a 12-ounce can of pop has 25. And because the apple contains fiber, its fructose content is absorbed into the bloodstream much more slowly, resulting in smaller effects on metabolism. But most importantly, fruit is full of antioxidants and minerals conducive to good health. Soft drinks have no such redeeming features. No matter what the sweetener industries say, cutting down on sucrose and HFCS-sweetened foods and drinks will have an impact on the obesity epidemic and will lead to better health. So I say, let’s drink to the stand taken by the World Health Organization. Just don’t make it a soft drink.