As of Friday, August 29, 2014
DEAR DOCTOR K: In your column you often distinguish between “good” and “bad” carbohydrates. What makes a carb good or bad?
DEAR READER: Carbohydrates — carbs — occur naturally in a variety of foods, from fruits, vegetables and milk, to breads, cereals and legumes. Carbs are also added to many foods, often in the form of sugar. Your digestive system transforms carbs into glucose (blood sugar). They are your body’s main source of energy.
Whether a carb is “good” or “bad” depends on several factors. Some of the most important are:
— Whether they are refined or whole;
— Their effect on your blood sugar level;
— Their fiber content.
REFINED VERSUS WHOLE. Refined carbs include white flour, white rice, soda, fruit drinks and sweets. The refinement process strips away many of the original carbohydrate’s valuable nutrients, fiber and vitamins.
Good carbs, on the other hand, are intact, or minimally processed. They include whole grains, which lower the risk of heart disease, diabetes and possibly stroke. Other minimally processed carbs include brown rice, oats, whole wheat flour, fruits and vegetables. (On my website, AskDoctorK.com, I’ve put a table with examples of healthy carbs to enjoy and refined carbs to avoid.)
EFFECT ON BLOOD SUGAR. Your body digests refined carbs and sugars quickly. This causes blood sugar levels to rise rapidly following a meal. When the pancreas — an organ in your abdomen — senses high levels of blood sugar, it produces bursts of insulin. Insulin lowers blood sugar levels by driving the sugar from the blood into the cells. The cells need it for energy.
So far, so good. The problem is that if your pancreas has to keep responding to sudden surges of blood sugar, many times a day, day after day, it gets pooped. After many years, the overworked pancreas can’t make insulin as well as it used to. That can lead to Type 2 diabetes.
Good carbs take longer to digest. As a result, blood sugar and insulin rise slowly and peak at lower levels. Fruits, vegetables and whole grains tend to keep blood sugar levels steady.
FIBER CONTENT. There are two types of fiber: insoluble and soluble. Insoluble fiber is found in the skin, peels and husks of fruits, vegetables and whole grains. It passes through your digestive tract without breaking down and helps prevent constipation.
Soluble fiber is chiefly found in oats, legumes (beans and peas) and a part of fruit called pectin. Soluble fiber improves blood sugar levels. And it decreases the level of LDL cholesterol in the blood, reducing the risk of heart disease.
Fruits, vegetables and whole grains are good sources of fiber.
For many years, people were told that low-fat diets were healthy. That’s wrong. Just as there are good and bad carbs, there are good and bad fats.
So stick with the good carbs and eat a balanced diet.