Dear Ms. Quinn:

Can you define what is meant by “sugar-free,” “reduced sugar,” “sugar alcohol,” etc.? It is quite confusing when shopping for such food items for a prediabetic.

— Jim in Pacific Grove, Calif.

Glad to, Jim. All the terms you find on a food label are strictly defined by the U.S. Food and Drug Administration.

“Sugar-free” means the food contains less than 0.5 gram (about an 1/8th of a teaspoon) of sugar per serving — a negligible amount. This definition also applies to terms such as “no sugar,” “sugarless,” or “zero sugar,” says the FDA.

For example, the “sugar-free” iced tea I just mixed up with some sliced lemons and mint leaves contains no sugar, according to the Nutrition Facts label, even though there is a “trivial amount of sugar” from added corn syrup solids. It can still be labeled “sugar-free” however because each serving contains less than a half-gram of sugar.

“Reduced sugar” can be claimed for a food that has at least 25 percent less sugar than its original form. For instance, one (8 ounce) cup of Tree Top Reduced Sugar Grape Juice Blend contains 18 gram of sugars (about 4 teaspoons) compared with 26 grams (about 6 teaspoons) in their Vineyard Grape Juice Blend.

“No Added Sugars” means no sugar-type ingredient has been added to the food. Plain yogurt with no fruit or added source of sugar, for example, can be labeled “No Added Sugars.” But it is not sugar-free because it contains the natural sugar from milk — lactose.

“Sugar alcohols” are a form of sugar and not alcohol in the intoxicating sense. Because they are poorly digested, they provide about half the calories and a smaller impact on blood sugars than regular sugar. Examples of sugar alcohols (aka “polyols”) include xylitol, sorbitol, mannitol, maltitol, and isomalt.

And here are a couple of other interesting facts about labels on sugar-containing foods:

“Low sugar” is not a defined term by the FDA and, as such, may not be used on food labels.

And the term “sugar” has a different definition than “sugars,” according to the FDA. “Sugar” specifically means sucrose (table sugar) that is half glucose and half fructose.

“Sugars” includes ALL sugars, including lactose in milk, fructose in fruit, honey and corn syrups.

For example, the first ingredient in the brownie mix I suddenly got an urge to bake (instead of working on my project) is “sugar” (sucrose). And the nutrition label on this product informs me there are 16 grams of sugars (plural) in one brownie, which include sugar (sucrose) as well as corn syrup.

— Barbara Quinn is a registered dietitian and certified diabetes educator at the Community Hospital of the Monterey Peninsula.