Carbohydrates seem to be in the news a lot these days. You either hear or read that if you want to lose weight, you shouldn’t eat carbohydrates, or that if you want to control your blood-glucose levels, there are some specific carbohydrates you should not eat. The question, then, is to sort out what’s important.
Don’t Forget: Carbs Are Important
Remember that foods containing carbohydrates are important for a healthy diet. Researchers consistently report that to decrease risk of chronic disease it is important to eat carbohydrates such as whole grains, fruits, vegetables and low-fat milk. Furthermore, it is glucose from carbohydrate foods that provides energy for your body to do all the activities you enjoy.
To use glucose for energy, you must have the right amount of insulin available. Even though protein and fat do not add glucose to the blood, the body does need insulin to use them correctly. In fact, gram for gram, protein stimulates as much insulin as does carbohydrate, and in people with type 2 diabetes it may even stimulate more insulin than carbohydrate does. It is important to balance carbohydrate and insulin to control diabetes and stay healthy.
In regard to carbohydrates, what are important factors for you to control? Many research studies have shown that if people with either type 1 or type 2 diabetes choose either a variety of starches or a variety of starches and sugars for meals and in both cases keep the amount of carbohydrate the same, the blood-glucose response is similar. So the first thing people with diabetes should focus on is the total amount of carbohydrate they eat for meals and snacks.
Keeping an Eye on the Glycemic Index
Research has also shown, however, that when carbohydrate foods are eaten separately and in 50-gram serving sizes, some foods do raise blood glucose more
than others. This variable rise is often referred to as the “glycemic index” of carbohydrates. Interestingly, foods containing sugars, either natural or added, tend to have a lower glycemic index than starches. The important question, then, is whether your A1C levels would improve if you chose only foods with a low glycemic index.
Twelve studies have compared diets based on foods ranked low on the glycemic index with diets based on foods high on the glycemic index. Six of the studies showed improvements in the subjects’ fructosamine test results
(a short-term measure of glucose control) when a low-glycemic diet was followed, while three showed no improvement. One study reported improvement in A1C levels, while eight did not. (Not all studies measured both tests.)
The bottom line is that some people may benefit from choosing low-glycemic foods, and some may not. By testing before and after meals, individuals can determine whether some foods will raise their blood-glucose levels more than others. This information could lead them to choose smaller portions of these foods in the future.
A New Concept: The Glycemic Load
Why haven’t all the studies shown blood-glucose improvement from diets composed of foods low on the glycemic index? It may be explained by a new concept that researchers at Harvard are using in their studies. It is called the “glycemic load.”
This concept suggests that it is both portion size and glycemic index that determine how foods affect blood-glucose levels. The glycemic load assumes that 50 percent of the glucose response is from the amount of carbohydrate in a specific food and 50 percent of the glucose response is from the glycemic index of that food. This concept has not been tested in clinical studies, but it does seem to combine the two factors that determine glucose response. Interestingly, researchers calculating the glycemic load of certain foods have found that pizza has a high glycemic load although not necessarily a high glycemic index. Carrots, on the other hand, despite having a high glycemic index, have a very low glycemic load.
Until more is known about the glycemic load of foods, what can people with diabetes do? First, pay attention to the total amount of carbohydrate in foods-we already know how important this is. Carbohydrate amounts are easily determined from food labels, books, many recipes, and so forth. Second, for fine-tuning, before-meal and after-meal glucose testing can be used to determine your own glycemic index. n
Marion J. Franz, MS, RD, CDE, is a nutrition/health consultant with Nutrition Concepts by Franz, Inc. She received the American Diabetes Association 2001 Charles H. Best Medal for Distinguished Service for the Cause of Diabetes.