How sweet it is.
Many Americans consumed their weight in sugar and corn sweeteners last year, eating an average 127 pounds, estimates the U.S. Department of Agriculture. And as artificial sweeteners -- such as aspartame, cyclamates and saccharin -- come under increasing scrutiny, sugar is looking sweeter all the time.
Yet, despite widespread consumption, myths stick to sugar like chocolate coats an ice cream bar.
Chief among these misconceptions is the idea that certain forms of sugar -- honey, for instance -- are more nutritious than others. The fact is, for the most part, sugar is sugar is sugar, be it corn syrup, brown sugar, processed white sugar, honey or maple syrup.
Ordinary table sugar "has gotten a reputation of being bad for you and some other sugars, especially honey, have gotten a reputation of being good for you," says Dawn Laine, a registered dietitian at the University of Minnesota's General Clinical Research Center.
But as Dr. David Jenkins of the Department of Nutritional Sciences at the University of Toronto's Faculty of Medicine puts it: "We have no evidence that honey is superior to table sugar."
All sugars are essentially the same chemically, and they all are broken down by the body into glucose -- a single sugar that circulates in the blood and provides energy to individual cells. Glucose is a monosaccharide -- a single-molecule sugar known as the common denominator of all other sugars and carbohydrates. Attach glucose to a fructose molecule (another single sugar), and a disaccharide -- or double sugar molecule -- is formed. Table sugar is a disaccharide known chemically as sucrose. Honey contains molecules of fructose and glucose, which are joined by an enzyme that's carried in the bodies of bees.
Blood glucose levels rise and fall in response to food, exercise, temperature and time of day. The body carefully regulates these shifts with the hormone insulin, which promotes the entry of glucose into cells. Cells break down glucose into carbon dioxide and water for energy. Extra glucose is stored in the liver as glycogen, which can be reconverted to circulating blood glucose when needed.
Exactly how fast blood glucose levels rise and fall after eating different foods is measured by a kind of sugar scoreboard developed by University of Toronto's Jenkins and his coworkers. Known as a glycemic index, this measure is providing a new look at how various foods, including different forms of sugar, affect circulating blood glucose levels. On the glycemic scale, pure glucose gets a score of 100.
"One of the claims for honey is that it doesn't raise blood sugar levels as quickly or as steeply as table sugar," explains Bonnie Liebman, chief of nutrition for with Center for Science in the Public Interest (CSPI), a nonprofit consumer group. "In fact, honey scored even worse than regular sucrose on the glycemic index." Honey scored 87; sucrose got a 59.
The point, says Toronto's Jenkins, is that "there are a broad spectrum of glucose responses to sugars, just as to starchy foods, and that there is great overlap. The physiological effects are not as clear-cut as we've allowed ourselve to believe."
How much a sugar, or any food, raises and lowers the glycemic index depends on how it's absorbed -- which is also a function, researchers say, of what combinations of foods are eaten. For instance, the sugar in an apple may be absorbed differently than the sugar in a glass of apple juice. This is probably because the apple contains fiber.
Another misconception about sugar is that certain foods, such as fruit, contain only one type of sugar. "A lot of people assume that all the sugar in fruit is fructose in part because the names are similar," says CSPI's Liebman. "While fructose does occur in fruit, you also get a lot of sucrose and glucose in fruit."
Fructose, another single sugar, like glucose, seems to generate the lowest glycemic index of any sugar, which means that blood sugar rises more slowly in response to fructose.
Then there are the hidden forms of sugar. "Much of the sugar some 62 percent that was formerly consumed in the household for homemade foodstuffs is now used in processed foods and beverages," reports the Sugar Association Inc., an industry group. For instance, CSPI says sugar provides a higher percentage of the calories in ketchup (some 63 percent of total calories) than it does in chocolate fudge topping (54 percent). Other unexpected sources of sugar include relish (62 percent of total calories) and cream-style corn (23 percent).
The sugars found in everything from broccoli and green beans to sugar cane and raisins are the end result of photosynthesis -- the solar-powered process that allows a plant to convert carbon dioxide and water to sucrose. The sucrose stored in sugar cane and sugar beets is extracted and processed to make ordinary table sugar.
In terms of calories, sugar ranks surprisingly low. One teaspoon contains about 16 calories. And one form of sugar -- molasses -- contains a significant amount of iron, plus lesser amounts of calcium, potassium and the B-vitamin niacin.
But critics point out that sugars are still the prime source of tooth decay -- a billion-dollar public health problem in the United States.
"What I try to get across to people is that there are not really any good or bad foods," says University of Minnesota's Laine, "it's learning how to combine the foods and use them in moderation."