DEAR DOCTOR K: It seems most people now agree that some carbohydrates are good for us. Are there rules of thumb for choosing carbs wisely?
DEAR READER: In yesterday's column, I ranted about some misinformation we've all heard: Fats are bad for you and carbohydrates ("carbs") are good. That's just plain wrong. We all need fats and carbs in our diets.
Yesterday's column talked about how to distinguish the "good fats" from the "bad fats." Today, let's distinguish "good carbs" from "bad carbs." Carbohydrates are found in a broad range of foods; some are healthy and some aren't. Table sugar, fruits and vegetables, and grains such as rice and wheat are all carbs. But they aren't equal in how they affect your body.
How is the difference determined? You may have heard the term "glycemic load," which describes both the amount of carbohydrate in a serving of food and how fast that amount will raise your blood sugar level.
Foods with a high glycemic load that flood your bloodstream with sugar all at once are less healthy. But high-carb foods that have a relatively low glycemic load can help protect against health problems. They're digested slowly, causing a gradual rise in blood sugar, rather than a harmful spike.
How can you tell the difference? Consider these characteristics:
- How heavily processed is the food? Finely ground white wheat flour is digested faster than coarsely ground (sometimes called "stone-ground") wheat flour, because the smaller pieces are digested faster.
- Whole-grain foods such as brown rice and barley have their fibrous casing intact. The casing slows digestion and contains nutrients that may lower the risk of some diseases. These include Type 2 diabetes, heart disease and several types of cancer, including cancer of the mouth, stomach, colon, gallbladder and ovaries.
- Is it really whole grain? Not all foods in the grocery store that claim to be "whole grain" really are. "Whole wheat" does not mean no refined flour. Look for labels that say "100 percent whole wheat" (or oats or rye or another grain). The first ingredient listed should be a whole grain.
- How much fiber is in the food? Whole-grain foods have more fiber than refined foods. Fiber slows digestion and prevents blood-sugar spikes.
- How much fat is in a meal or snack? You'll slow the rise in blood sugar from carbs by combining them with protein or fats. Fats take longer to digest than carbohydrates and might translate to a less detrimental effect on your blood sugar. Just make sure that the fat or protein is a healthful one. A handful of nuts is a better snack than a fat-filled cookie. Nuts are largely good fats; cookies are definitely not.
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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