All About Carbohydrates: By Naomi Cook

Naomi Cook earned her bachelors in Animal Science from Cornell University and received her masters from NYU in Science Education. Currently Naomi teaches AP Biology in Wetchester, NY. She includes concepts from both Type 1 + 2 Diabetes in her core curriculum.

It’s virtually impossible to eat any food that doesn’t contain carbohydrates. This is because all biomass on Earth has its origins in photosynthesis, which produces glucose. It’s also impossible to sustain oneself on a diet that excludes all carbohydrates, since glucose is the main molecule from which a living organism derives its energy for life functions. Why then has it developed such a bad reputation? Probably because diets that are high in simple sugars, a type of carbohydrate, are linked to obesity and the onset of Type 2 Diabetes. And considering that 23.1 percent of the US population 60 years and older suffer from Diabetes, it makes sense that we are hearing a lot about carbohydrates. (National Institute of Diabetes and Digestive and Kidney Diseases)

But information on carbohydrates seems confusing to me. Molecularly, carbohydrates come in many different forms, and our bodies process, store and use each form differently. Depending on the type of carbohydrate we are ingesting, our hormones will respond very rapidly, which is usually not so good, more slowly which is better, or not at all, as is the case with a Diabetic. This makes it difficult to know exactly what a nutrition label means for your body when it says that it contains 23 grams of carbohydrates.

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The molecular building blocks of carbohydrates are simple sugars like sucrose (table sugar) and glucose (the product of photosynthesis). Plants synthesize much longer chains of simple sugars for storage. An example of a storage carbohydrate is starch. They will also synthesize longer chains of simple sugars for structural purposes. An example of this is fiber. When we eat food that lists carbohydrates on its nutrition label, we are probably eating a combination of simple sugars and more complex carbohydrates.
Simple sugars will be absorbed quickly into the blood. In order to respond to the rapid rise in blood glucose levels, the pancreas must respond quickly by producing large amounts of insulin. Over time, the spikes in insulin causes cells to become unresponsive to the insulin and Type 2 Diabetes may develop. The more processed a food is, the more simple sugars it tends to contain. Manufacturers add it to food so that it tastes better. Unfortunately, nutrition labels often do not distinguish between added sugars and carbohydrates that are found naturally in foods.

Longer chains of sugars which may be referred to as complex carbohydrates must be broken down in the digestive system and are generally released into the blood more slowly. This is less stressful on the body. The less processed a food is, the more slowly its constituent sugars seem to be released into the blood stream. Whole grains, fruits and low starch vegetables are broken down and released slowly, causing gradual increases in blood sugar. (Harvard School of Public Health)

Humans are unable to digest fiber, the carbohydrate constituent of a plant’s cell wall. As a result, these sugars are never released into the blood stream and do not add to the calorie content of a food. They do however bind to fats in the intestines, carrying fatty substances out as waste, and contribute to a person feeling full. Therefore, when looking at the nutrition label, it is important to take the fiber content into consideration when looking at the overall carbohydrate content. Fiber does not increase blood glucose levels.

Since the rate at which sugars are released into the blood seems to play an important role in how much stress your body experiences after a meal, scientists have begun to categorize foods based on their glycemic index. For example, potatoes are filled with the complex carbohydrate starch, which seems to be broken down and released as simple sugars into the blood just as quickly as the added simple sugars from a processed food product enter the blood stream. Foods with a lower glycemic index release their sugars more slowly than foods with a higher glycemic index. While it is still debatable whether or not foods with a high glycemic index can be linked to things like Type 2 Diabetes or obesity, it is a unique way of analyzing different foods. It does not however, take into account carbohydrate density of foods. For example, watermelon has a high glycemic index, but its carbohydrate density is so low, that it ends up releasing very little sugar into the blood. (Harvard School of Public Health) A comprehensive glycemic index of foods may be found at http://www.glycemicindex.com/.

When planning meals, it is still helpful to just go with the nutrition label. The American Diabetes Association recommends that Diabetics take 45-60 grams of carbohydrates per meal. (American Diabetes Association) Foods that contain carbohydrates, whether complex or simple, need to be taken into account when Diabetics are planning meals. These foods are breads, cereals, crackers, rice, fruit, yogurt, juice, milk, beans and soy products, potatoes, corn, sweets and juice. Non-starchy vegetables such as lettuce and peppers do contain carbohydrates, but very little in comparison. (American Diabetes Association) Again, it is probably best for as many of those 45-60 grams of carbohydrates to be from unprocessed foods such as whole grains, fruits, vegetables and beans.

The American Diabetic Association has an incredibly helpful interactive website that allows users to find the nutrition information on almost any natural and many processed foods. It also allows the user to create meals by adding ingredients and changing serving sizes to view the total nutrition content of the full meal. Nutrition content of foods can be directly compared, and the website can find healthier alternatives to ingredients. I have found it helpful even though I am not a Diabetic. You may access the link here. Happy eating!

Work Cited
American Diabetes Association. "Carbohydrate Counting." February, 2009.

Harvard School of Public Health. "Carbohydrates: Good Carbs Guide the Way." February, 2009.

National Institute of Diabetes and Digestive and Kidney Diseases. National Diabetes Statistics, 2007 fact sheet. Bethesda, MD: U.S. Department of Health and Human Services, National Institutes of Health, 2008.

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