Carbohydrates: Good or Bad?

By Paulette Lambert, RD, CDE, Dir of Nutrition, CHLI

When it comes to making healthy nutritional choices, not all carbohydrates are created equal.

There has been a tremendous amount of press over the past decade related to the role that carbohydrates play in our diet, and the continuing popularity of low-carb diets has, for many, led to the perception that foods high in carbohydrates are unhealthy.

The reality is that carbohydrates, like fat and protein, are valuable nutrients that help support life. Carbs provide us with fuel for physical activity and for normal body functions, and they deliver essential vitamins, minerals, and many important antioxidants.

Here is some basic nutrition science about this sometimes-misunderstood nutrient:

  • Carbohydrates come in three forms: sugars, starches, and fiber. Sugars are the basic building block; starches and fiber are long chains of sugars.
  • Simple carbohydrates are made of one to three sugar molecules and include fruit sugar and sucrose.
  • Complex carbohydrates, which include starchy vegetables, are composed of longer chains of carbs such as grains, which the body breaks down into single sugar molecules so that they can be absorbed.
  • Fiber, due to its structure, cannot be broken down and passes through the body undigested; it has many health properties such as the ability to lower cholesterol and blood pressure.

 

Glycemic Index and Glycemic Load: Helpful Tools Can Lead to
Healthy Choices

The Glycemic Index (GI) was developed to classify how quickly and to what extent a carbohydrate food boosts blood sugars compared with glucose. The higher the food’s Glycemic Index, the faster and stronger the effects are on blood sugar and insulin. Glucose has a GI of 100, so if a food has a GI of 30 percent, it increases blood sugar only 30 percent of what pure glucose would. Some starches, like white potatoes, convert into simple sugars in the body almost as fast as pure glucose, whereas others, such as black beans, take longer to convert.

The higher and faster the blood sugar goes up, the more insulin is needed to get that sugar to the cells for energy. High insulin levels are associated with more fat cell development and increased hunger that contributes to obesity, as well as low-level chronic inflammation that causes damage to cells and is linked to other problems, such as coronary heart disease, possibly some cancers, and insulin resistance that can lead to diabetes.

The GI is not a totally accurate guide from which to make food choices; it is really a laboratory measurement. In the real world, what and how we eat (combinations of foods and various cooking methods) can affect GI. The GI also does not tell us how much digestible carbohydrate is in the food that we are eating.

A more accurate guide is a measurement called the glycemic load, which takes into account both the amount of carbohydrate in the food and the impact on blood sugar. Glycemic load is determined by multiplying GI by the amount of total carbohydrates the food contains. A load of more than 20 is high, 11 to 19 is medium, and 10 or less is low. An apple, for example, has a GI of 38 percent and contains 15 grams of total carbohydrate, giving it a glycemic load of 6, which is low. This method reflects a food’s effect on the body rather than just a laboratory measurement.

Noting the glycemic load in specific foods can help us make better dietary choices that can control blood sugar levels and help prevent chronic disease and aging. For those with diabetes, eating a diet that takes glycemic load into account may help control the disease. Whether you are managing a chronic condition or just looking to maintain long-term good health and slow down aging, becoming aware of the effect of foods with a high glycemic load can make a real difference.  _