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Sugar alcohols are half carbs

3 min read

DEAR DOCTOR K: I have Type 2 diabetes. Many low-carb and sugar-free products contain “sugar alcohols.” What are they? Do they count as carbohydrates?

DEAR READER: Type 2 diabetes is marked by elevated levels of blood glucose, or sugar. Untreated or poorly controlled diabetes can lead to serious complications including heart attacks, kidney failure, amputation and blindness.

An important part of controlling blood sugar involves making healthy food choices. People with diabetes should be particularly mindful of carbohydrates. Carbohydrates are like a chain with a number of links. When a carbohydrate with many links enters your stomach and intestine, it is broken down into multiple small pieces. The smallest piece, the single link in the chain, is primarily what is absorbed into the blood. The most important small sugar is glucose.

Table sugar is a two-link carbohydrate that is easily broken down into glucose. If you were to swallow 10 teaspoons of table sugar, it would quickly enter your bloodstream. That’s not good. You want to eat carbohydrates that are broken down in the gut more slowly so that they enter the bloodstream more slowly.

We’ve talked about this concept before: Foods that contain carbohydrates that are rapidly broken down into glucose have a high glycemic index and high glycemic load. A steady diet of such foods is not healthy for people with diabetes — or for anyone else.

Carbohydrates are the major component of bread, pasta, cereals, fruit, milk, vegetables and beans. They have more of an impact on blood sugar levels than fats and proteins do.

For years, doctors advised people with diabetes to avoid table sugar or foods with lots of sugar. That’s still good advice, of course. But these days, the taboo against sugar has been replaced by an emphasis on overall carbohydrate control.

What does that mean? First, limit carbs to about half of your total calories for the day. Equally important, primarily eat carbohydrates with a low glycemic load.

You asked about the many so-called sugar-free foods that contain sugar alcohols. Examples of sugar alcohols (also called polyols) include sorbitol, xylitol and mannitol. These sweeteners are often found in sugar-free chewing gum, candy, cookies and ice cream.

Polyols do contain some calories and carbohydrates. But only half of the sugar alcohol is digested and absorbed into the bloodstream. On the other hand, nearly all the table sugar in the diet enters the blood. If you count carbohydrates, as many people with diabetes do, count half the calories from sugar alcohols as carbohydrates.

Products containing sugar alcohols do have drawbacks. If eaten in large quantities, for example, they can have a laxative effect.

In summary, reach for healthy sources of carbohydrates — vegetables and fruits — over candy and soft drinks. And choose whole grains such as brown rice, whole-wheat flour and rolled oats over refined carbs such as white rice, white flour, white pasta and instant oatmeal. You’ll be doing your blood sugar a favor while getting a lot more nutritional bang for your buck.

(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.)

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