The Bitter Side Of Sugars

Bathroom scales rarely give reason to celebrate. By the time you step up and wait for the creaking springs to equilibrate, an uncomfortable feeling grabs hold: How much damage did that chocolate glazed doughnut do?

On average, Americans weigh 25 lb more today than they did 50 years ago, at a cost of $147 billion in annual obesity-related health care, according to the Centers for Disease Control & Prevention. Overeating (my problem) and a sedentary lifestyle (not my problem) are key reasons. But scientific evidence trickling in suggests that eating less and exercising more may not be enough to help solve the obesity crisis. We need to cut out most table sugar and other caloric sweeteners from our diets.

The dietary sugar focus has mostly been on high-fructose corn syrup (HFCS). This sweetener cropped up in the U.S. in the 1970s when sugar import tariffs and corn subsidies suddenly made HFCS a cheap sugar substitute. By 1985, HFCS had replaced sugar in many processed foods and most soft drinks; the HFCS fraction of total added sugars consumed in the U.S. went from none to about half. HFCS accounts for less than 10% of caloric sweeteners used in the rest of the world.

During the past decade, nutritionists, medical researchers, consumer advocacy groups, and corn refiners went through a cyclical debate over whether sugar and HFCS are nutritionally different or nearly enough the same.

Table sugar is sucrose, a disaccharide made of equal amounts of fructose and glucose derived from cane or sugar beet juice. By contrast, HFCS is a mixture of free fructose and glucose. It’s made by first hydrolyzing the polysaccharides in cornstarch to form glucose and then enzymatically isomerizing most of the glucose to fructose. The final fraction of fructose is adjusted by diluting with more glucose. HFCS-55, containing a 55:42 mixture of fructose and glucose, is typically used in soft drinks; HFCS-42, a 42:53 mixture, is typically used in processed foods.

By now, all parties agree there’s no nutritional difference between sugar and HFCS. And by definition, a calorie’s worth of fructose is equal to a calorie’s worth of glucose, whether it is derived from HFCS or from sucrose hydrolyzed during digestion.

However, the body doesn’t care about definitions. We absorb fructose and glucose by different mechanisms. Once in the bloodstream, the two sugars follow different biochemical pathways: Insulin-regulated glucose is involved in getting energy into cells throughout the body, whereas insulin-independent fructose plays a role in glycogen, triglyceride, and cholesterol production in the liver.

The real issue isn’t HFCS versus sugar, or fructose versus glucose. Rather, it is that too much sugar in any form is contributing to obesity, type 2 diabetes, high blood pressure, heart disease, cancer, and perhaps even autism. That is where the sweetener debate has now turned.

To hear endocrinologist Robert H. Lustig of the University of California, San Francisco, tell it: “HFCS and sugar are equally bad. They are poison.” And even as most people have reduced salt and fat in their diet to lower the risk of heart disease, as science has told us to do, we haven’t lost any weight, Lustig argues. That’s because we haven’t cut out the sugar, or at least not enough yet to make a difference.

Lustig is a pioneer in the war against sugar. His May 2009 lecture, “Sugar: The Bitter Truth,” became a hit on YouTube and ultimately spawned a flurry of news reports earlier this year on sugar and the American diet. Scientists like Lustig are moved to preach because they believe regulatory agencies are slow to act.

He posits that people originally got their sugar in small amounts from the fructose in fruit. Over time, our brains became wired to be addicted to fructose, Lustig believes. We now tend to gorge on sugar and HFCS, he says, and it is the subsequent abnormal spikes in insulin that are causing trouble: The extra fructose and glucose effectively act like endocrine disrupters, Lustig suggests.

Whether the sugar-is-toxic theory holds up remains to be seen, but Lustig and other scientists have redirected the focus on the American obesity crisis and are getting people to think more seriously about how much added sugar they consume. In 1970, the average person in the U.S. consumed about 119 lb of added sugar, according to the Department of Agriculture’s Economic Research Service. The amount peaked at about 151 lb per year in 1999, but it dropped to about 132 lb in 2010.

Nutritionist Barry M. Popkin of the University of North Carolina, Chapel Hill, another sugar war veteran, has suggested significant further cuts are possible by replacing HFCS and sugar in all beverages with noncaloric sweeteners. We don’t know whether the use of such sweeteners has any long-term health effects. But a study reported earlier this year by Popkin and colleagues shows that substitution has the desired effect: People who replaced sugar-sweetened beverages with artificially sweetened drinks or water achieved an average 2.5% weight loss over six months.

To phase out sugars from our diets will require a bolder approach than just relying on reading nutrition facts and willpower. New York City Mayor Michael R. Bloomberg is taking a stab at it by trying to ban the sale of supersized sugary soft drinks. But that tactic isn’t likely going to work because people feel their individual rights are being trampled upon.

In the end, we might just need to use scare-tactic labeling as we have done to curb cigarette smoking: “Surgeon General’s Warning: This product contains high-fructose corn syrup and/or sugar and may make you fat and cause health problems.” It’s food for thought.