A Helping of Sugar Truths for Sweet Tooths

We recently received two questions about sugar and, frankly, both of them surprised us. The first was from a reader who said she had looked everywhere to find the U.S. Department of Agriculture’s recommended daily allowance for sugar and was totally baffled. The second question concerned a rumor that eating sugar removed other nutrients from the body.

In order to evaluate what we have to say about sugar, truth-in-advertising laws require us to admit that we both have a sweet tooth. So, having gotten that out of the way, we can now try to clear up some of the confusion.

Sugar belongs to the class of foods known as simple carbohydrates. Along with more complex carbohydrates, these all break down to glucose in the body, and glucose is carried by the blood to provide energy for cells. Any glucose that isn’t needed by cells is converted into glycogen, which is stored either in the muscles and liver or as body fat.

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There are dozens of types of sugars. Scientifically, they are called fructose (fruit sugar), glucose (also known as dextrose or corn sugar), maltose (malt sugar), lactose (milk sugar) and sugar alcohols, such as sorbitol and xylitol. Sometimes they are given names that reflect where they come from, such as honey, maple syrup and corn syrup.

It is hard to escape sugar entirely. It is everywhere: in the obvious places like candy, soft drinks and the sugar bowl. It also shows up where we might not expect it--in ketchup, frozen dinners, breads, canned goods, fruits, vegetables and dairy products.

Complex carbohydrates (which are primarily starches) break down to glucose just like sugar does. Starch is the means by which plants store energy in the same way that glycogen is the way humans store it. But it takes a little longer for complex carbohydrates to break down (because they are more complex molecules), and the bonus is that complex carbohydrates carry other nutrients along with the sugar.

When you get simple sugar in fruits and vegetables, you also get many other nutrients plus fiber. When you get sugar in a candy bar or a soft drink, you get nothing but calories. Well, maybe a little fat thrown in for good measure. As our reader already discovered, there is no RDA for refined sugar, not even a maximum recommended amount, like there is for sodium. But if you look at the very tip of the USDA Food Pyramid, you will find that sugar joins alcohol in a small space that says eat sparingly.

And to the second reader who inquired about whether it was true that sugar leached other nutrients from the body, we’d like to emphasize that this is not true--it’s one of many myths about sugar. However, having said that, it is true that if you substitute simple sugars for other foods that contain essential nutrients such as protein, vitamins, minerals, antioxidants and even non-nutrients like fiber, you will end up with an inferior diet and may experience ill effects because of it.

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Some of the other myths that have persisted about sugar include the following:

* Sugar causes obesity.

Actually, eating any kind of calories in excess of the ones you burn will cause you to gain weight. A person whose diet consists of large quantities of cakes, cookies, ice cream and other very sweet treats is probably getting more calories from the fat these foods contain than the sugar. A teaspoon of sugar has only 16 calories, while a teaspoon of fat would have about 36 calories.

* Myth: Only refined sugar causes cavities.

While refined sugar is the leading cause of tooth decay, the sugars in fruit and milk may also promote tooth decay, as can the sugars in bread and rice. Frequent brushing and flossing can help alleviate this problem.

* Sugar makes children hyperactive.

Although you’d get an argument from a lot of parents on this issue, a number of well-controlled studies have failed to show a correlation.

* Sugar is addictive.

It certainly seems that way, but again, there is no scientific evidence for this.

* Honey and brown sugar are healthier than table sugar.

Sugar is sugar is sugar, and honey and brown sugar offer no advantages at all.

* Using sugar substitutes helps people lose weight.

Of course, in theory this should be true if you substitute directly. However, there is some evidence that sugar substitutes (much like fat substitutes) give people a false sense of accomplishment, and they reward themselves by adding calories to their diets in other places. Specifically, if you drink a diet cola instead of the full octane version you usually have, instead of benefiting from the calorie deficit, you might be tempted to have a cookie as well.

In the past 30 years that sugar substitutes have been readily available, Americans have become heavier and heavier. Fat substitutes often try to add flavor by increasing the amount of sugar in the food, sometimes by an astonishing amount. You may consume fewer fat calories but not overall calories.

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If you have questions you’d like to have answered in this column, please send e-mail to daogar@uclink4.berkeley.edu, fax to (510) 642-2857 or send a regular letter to Dale Ogar, School of Public Health, UC Berkeley, Berkeley, CA 94720-7360. We regret that we cannot answer questions personally.