- The Washington Times - Monday, February 14, 2005

Believe it or not, all carbs aren’t the same, says Amanda Smith, clinical dietitian at Georgetown University Hospital.

With the recent low-carbohydrate craze, dieters avoid foods such as pasta and potatoes to limit fluctuations in their blood sugar. The glycemic index ranks carbohydrates by how much a person’s blood sugar rises immediately after eating.

Ms. Smith usually uses the index when teaching diabetic patients how to adjust their diets, but recently, people on low-carb diets have been using the table for weight-loss purposes.

She says she doubts an entire diet should be designed specifically on the index’s information.

“Everybody is different,” Ms. Smith says. “Somebody may eat a baked potato, and it may not make their blood sugar go up as much as the next person.”

Other health professionals think the concept of the index is too complicated to explain and put into practice.

Proponents of basing a diet on the glycemic index, however, maintain that eating foods lower on the list could provide many health benefits, including weight loss.

The glycemic index compares foods’ carbohydrate content, gram for gram, says Dr. Thomas Wolever, a professor in the department of nutritional sciences at the University of Toronto.

Dr. Wolever helped create the table with Dr. David Jenkins, who is a professor in the same department at the university. Their goal was to make a table for diabetic patients, listing the foods that don’t cause large increases in blood sugar.

At the time, glucose was used as the standard to which other foods were compared. Since then, tests have been done using white bread as the reference, but Dr. Wolever still prefers to use glucose. Dr. Wolever studied the blood sugar response of about 40 subjects and averaged the values of their tests to create the glycemic index.

In 1981, the doctors made public their research, which provided a new way to classify carbohydrates. Generally, the carbohydrates with the highest glycemic indexes, including white or wheat bread, bagels, mashed potatoes and most breakfast cereals, break down rapidly during digestion, causing a fast rise in blood sugar.

Carbohydrates with the lower glycemic indexes, including cold potato salad, pasta, oatmeal, legumes, barley, parboiled rice and whole-grain breads, break down slowly. After digestion, they release glucose into the blood stream at a gradual rate, which causes a smaller rise in the blood sugar.

Therefore, eating according to the glycemic index would improve a person’s control of diabetes, he says.

“It seems quite important that the rate to which we get the carb into the body can affect both health and disease,” Dr. Wolever says. “Where this will all lead, I don’t know. There is evidence that low [glycemic index] affects risks for heart disease, diabetes, cancer, and it can affect body weight regulation, thinking and memory.”

Eating foods low on the glycemic index doesn’t mean a person would never eat a food that is higher on the table, such as white bread, Dr. Wolever says. If a person wants to eat a food such as rice, Dr. Wolever suggests choosing a type of rice lower on the list — parboiled rice, for example.

“If you’re young, fit and an athlete, high G.I. foods could be good or perfectly fine,” Dr. Wolever says. “If you’re in the middle of a marathon, you drink those sports drinks, and they get in the bloodstream quickly.”

Because the foods low on the glycemic index break down more slowly, the body feels fuller longer, which helps people lose weight, says Rick Gallop, author of “Living the G.I. Diet,” past president of the Heart and Stroke Foundation of Ontario.

“It keeps your appetite from coming back,” Mr. Gallop says. “The whole idea is to eat less without going hungry.”

Without even realizing it, most people eat a breakfast that is high on the glycemic index, Mr. Gallop says. The majority of foods made from flour, such as highly processed breakfast cereals, cause blood sugar to rise.

“At 10 o’clock, you are reaching for your sugar fix with a danish and cereal,” Mr. Gallop says. “If you have a bowl of old-fashioned oatmeal, it will be rib-sticking.”

Although eating according to the glycemic index does keep blood sugar more steady, changing eating habits can be difficult, says registered dietitian Elizabeth Glynn, an advanced practice diabetes nutrition educator at Inova Diabetes Center at Inova Fairfax Hospital. She tells her patients to make simple changes, such as eating whole-grain bread instead of white bread.

“Only about 10 percent of the people I work with are willing to change their food habits,” Ms. Glynn says. “Sometimes, people eat what they eat because of their job and school schedule.”

The glycemic index is a good tool for people who are putting a fair amount of time into considering what they eat, she says. However, other factors can affect a person’s blood sugar, such as how the food is stored and cooked.

Most diabetic patients can see improvements in their health without following the table to a T, Ms. Glynn says, although most diabetics also need medicine to control their blood sugar. She tells her patients to consider the total amount of carbohydrates on their plates during a meal.

“The idea makes a lot of sense, but it gets very complicated,” Ms. Glynn says. “Professionals in Australia and Canada have embraced teaching it more so than professionals in this country, partly because it’s so complex.”

Generally knowing what foods raise blood sugar is a good barometer for most diabetics, says Dr. Christopher D. Saudek, professor at the Johns Hopkins University School of Medicine in Baltimore. He is a former president of the American Diabetes Association.

“It’s a little bit oversimplified to think of foods just for their glycemic index number,” Dr. Saudek says. “People with diabetes have enough burden to recognize carb portions, instead of where the carb is on a long list of foods.”

Along with considering how many carbohydrates are in each meal, a diabetic should eat a consistent amount of carbohydrates from day to day, says Dr. Michelle Magee, director of the MedStar Diabetes Institute at Washington Hospital Center.

“We adjust the diabetes medicine so we’re not dealing with a shifting amount of carbohydrate,” Dr. Magee says. “We want to know the sugar after the meal will be controlled with the medicine that’s given with the meal.”

Further, Dr. Magee is unsure that eating according to the glycemic index will help a person seeking weight loss. The concept doesn’t have widespread acceptance in the U.S. medical community, he says.

“If you eat foods of a high glycemic index and make the blood sugar go up a lot, it will raise the amount of insulin,” Dr. Magee says. “You might have problems controlling your weight, but it’s not certain.”

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