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DEMYSTIFYING: “Good” vs. “Bad” Carbohydrates

The popular press, particularly magazines and websites that cater to health and fitness enthusiasts, make an effort to simplify decisions about what to eat and what not to. Writers employ phrases like “good vs. bad” or “eat this! not that!” in an effort to make their message stick. However, we at D21 want to encourage our readers to be more discerning. So what, exactly, defines a carbohydrate as “good” or “bad”?

Most of us know that carbohydrates are a vital part of a nutritious and balanced diet. We know that carbohydrates is a scientific term for sugars and that sugar is used by the body for energy. Most of us have heard of simple and complex carbs, and we understand that some carbs are better for us than others. Enter the idea of “good” vs. “bad” carbohydrates.

“GOOD” vs. “BAD” IS A FLAWED WAY TO DISCRIMINATE BETWEEN CARBS

Several factors come into play when defining a carbohydrate as possibly “good” or “bad”. Many times, these descriptors are equated with complex and simple carbohydrates: good = complex and bad = simple. However, this is an oversimplification. Not only is the complexity of the carbohydrate relevant, but also the carbohydrate’s effect on blood sugar (glycemic index), nutrient content (whole grain, fiber, vitamins & minerals), and an individual’s nutritional needs.

Simple carbohydrates (also called mono- or disaccharides) are single molecules or two linked sugars. Complex carbohydrates (polysaccharides) are chains of many sugars.

carbs
All carbohydrates must be broken down into individual sugars, monosaccharides, during digestion in order to pass from the digestive tract into the blood. So, if both simple and complex carbohydrates are absorbed by the body as monosaccharides, then why is the form of a carbohydrate important? One general reason is that simple carbohydrates can be easily absorbed into the bloodstream, elevating blood sugar, while complex carbohydrates require further digestion to be broken down into absorbable monosaccharides.

However, simple carbohydrate foods do not necessarily elevate blood sugar faster than complex carbohydrates. Recognizing this, a group of researchers, led by David Jenkins at the University of Toronto, developed the concept of a glycemic index. Glycemic index is a measure of how quickly the glucose from food is absorbed into the blood. These scientists determined that “…the extent to which different carbohydrate sources raise blood glucose…indicate that simple carbohydrate exchanges…do not predict the physiological response.”1 They mean that, simple carbs don’t always raise blood sugar faster than complex carbs. Indeed some foods, such as potatoes, that contain complex carbohydrates, can elevate blood sugar faster than fruits which contain simple mono- and disaccharides. So, what other factors might help discriminate between sources of carbohydrates?

NOT ONLY IS THE COMPLEXITY OF THE CARBOHYDRATE RELEVANT, BUT ALSO THE CARBOHYDRATE EFFECT ON BLOOD SUGAR, NUTRIENT CONTENT, AND AN INDIVIDUAL’S NUTRITIONAL NEEDS.

Factors such as the whole grain and dietary fiber content of many carbohydrate-rich foods as well as the nutritional quality (micronutrients like vitamins and minerals) and the body’s nutritional needs at a given time all are important considerations.

The quality of the carbohydrates you consume is more important even than the amount of carbohydrate. So, how can you identify high-quality carbohydrates? Looking for whole foods that are not (or minimally) processed is key in identifying healthy foods of all types, not just carbohydrates. Consider the following foods which have different glycemic indexes as well as varying nutritional value:

LOW GI FOODS
beans, seeds, nuts, milk, bran, some fruits (apples, peaches, citrus)

MEDIUM GI FOODS
whole grains (brown rice, whole wheat, oatmeal), many fruits

HIGH GI FOODS
healthy options
sweet potatoes, corn, bananas, mangos, raisins
nutritionally deficient options
processed grains (white bread, white rice), desserts, sweet beverages (soda, energy drinks)

Carbohydrate
So, what do you take away from all this? First, be skeptical of information you see in the popular press. Do research before making changes to your diet and lifestyle. Look to reputable sources for guidance in making sustainable improvements in your life.

Second, think about your own diet as well as how your body reacts to food, namely your feelings of satiety and hunger, then consider the quality of the carbohydrates in your meals. Remember that low and medium GI foods are good at balancing your blood sugar throughout the day. These foods provide nutritious energy sources when consumed in proper portion sizes.

High GI foods that are healthy, like sweet potatoes and bananas which are high in key nutrients, are excellent choices when your body is depleted after workouts or when eaten in modest portions as part of a meal with low/med GI foods or when you are anticipating extended physical activity (that’s why raisins and dates are popular amongst endurance athletes). However, processed grains, desserts, and sugar-laden drinks are an indulgence, not a nutritious choice and should be consumed sparingly, if at all.

THE REAL CONSIDERATIONS ARE ABOUT THE NUTRITIONAL QUALITY OF THE FOOD YOU EAT AND HOW IT MEETS YOUR BODY’S NEEDS.

A closer look shows that the descriptors “good” and “bad” are insufficient to characterize carbohydrates. Healthy foods have a place on most plates. The real considerations are about the nutritional quality of the food you eat and how it meets your body’s needs. We encourage you to dig deeper into the question of healthful carbohydrates.

References & Resources

1. Jenkins et al. (1981) Glycemic index of foods: a physiological basis for carbohydrate exchange. The American Journal of Clinical Nutrition

* The Nutrition Source from Harvard’s School of Public Health

* glycemicindex.com from the University of Sydney

 

The contents of this article & website are for educational purposes and are not intended to offer individualized medical advice. You should seek the advice of your physician or other qualified health professional with any questions you may have about medical conditions. Always adhere to the advice given to you by a medical professional, even if it is different from the information provided on this website

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