The skinny on carbohydrates

What Are Carbohydrates?

Carbohydrates are found in a wide array of foods—bread, beans, milk, popcorn, potatoes, cookies, spaghetti, soft drinks, corn, and cherry pie. They also come in a variety of forms. The most common and abundant forms are sugars, fibers, and starches. 

Carbohydrates were once grouped into two main categories. Simple carbohydrates included sugars such as fruit sugar (fructose), corn or grape sugar (dextrose or glucose), and table sugar (sucrose). Complex carbohydrates included everything made of three or more linked sugars. Complex carbohydrates were thought to be the healthiest to eat, while simple carbohydrates weren't so great. It turns out that the picture is more complicated than that. The digestive system handles all carbohydrates in much the same way—it breaks them down (or tries to break them down) into single sugar molecules, since only these are small enough to cross into the bloodstream. It also converts most digestible carbohydrates into glucose (also known as blood sugar), because cells are designed to use this as a universal energy source.


Fiber is an exception. It is put together in such a way that it can't be broken down into sugar molecules, and so it passes through the body undigested. Fiber comes in two varieties: soluble fiber dissolves in water, while insoluble fiber does not. Although neither type nourishes the body, they promote health in many ways. Soluble fiber binds to fatty substances in the intestines and carries them out as a waste, thus lowering low-density lipoprotein (LDL, or bad cholesterol). It also helps regulate the body's use of sugars, helping to keep hunger and blood sugar in check. Insoluble fiber helps push food through the intestinal tract, promoting regularity and helping prevent constipation.

When you eat a food containing carbohydrates, the digestive system breaks down the digestible ones into sugar, which then enters the blood. As blood sugar levels rise, special cells in the pancreas churn out more and more insulin, a hormone that signals cells to absorb blood sugar for energy or storage. As cells sponge up blood sugar, its levels in the bloodstream begin to fall. That's when other cells in the pancreas start making glucagon, a hormone that tells the liver to start releasing stored sugar. This interplay of insulin and glucagon ensure that cells throughout the body, and especially in the brain, have a steady supply of blood sugar.

In some people, this cycle doesn't work properly. People with type 1 diabetes (once called insulin-dependent or juvenile diabetes) don't make enough insulin, so their cells can't absorb sugar. People with type 2 diabetes (once called non-insulin-dependent, or adult-onset diabetes) generally start out with a different problem—their cells don't respond well to insulin's "open up for sugar" signal. This condition, known as insulin resistance, causes blood sugar and insulin levels to stay high long after eating. Over time, the heavy demands made on the insulin-making cells wears them out, and insulin production slows, then stops.

Insulin resistance isn't just a blood sugar problem. It has also been linked with a variety of other problems, including high blood pressure, high levels of triglycerides, low HDL (good) cholesterol, and excess weight. In fact, it travels with these problems so often that the combination has been given the name metabolic syndrome. (1) Alone and as part of the metabolic syndrome, insulin resistance can lead to type 2 diabetes, heart disease, and possibly some cancers.

Genes, a sedentary lifestyle, being overweight, and a diet rich in processed carbohydrates can each promote insulin resistance. (The combination is far worse.) Data from the Insulin Resistance Atherosclerosis Study suggests that cutting back on refined grains and eating more whole grains in their place can improve insulin sensitivity. (2) As described in "Health Gains from Whole Grains", the benefit of eating whole grains extends far beyond insulin to helping prevent type 2 diabetes, atherosclerosis (the build-up of cholesterol-filled patches that clog and narrow artery walls), heart disease, colorectal cancer, and premature death from noncardiac, noncancer causes. PLEASE TAKE HEED! 

The best sources of carbohydrates—whole grains, vegetables,fruits and beans—promote good health by delivering vitamins, minerals, fiber, and a host of important phytonutrients. Easily digested refined carbohydrates from white bread, white rice and other refined grains, pastries, sugared sodas, and other highly processed foods may contribute to weight gain, interfere with weight loss, and promote diabetes and heart disease.


Five quick tips on adding good carbohydrates to your diet: 

1. Start the day with whole grains. Try a hot cereal, like old-fashioned oats, or a cold cereal that lists a whole grain first on the ingredient list. I prefer hot cereal like oatmeal. Be careful of cold cereal, sometime the sugar content is high and that defeats the purpose.

2. Use whole grain breads for lunch or snacks. Confused about how to find a whole-grain bread? Look for bread that lists as the first ingredient whole wheat, whole rye, or some other whole grain —and even better, one that is made with only whole grains, such as 100 percent whole wheat bread. Or try this recipe for hearty whole grain bread.

3. Bag the potatoes. Instead, try brown rice, bulgur, wheat berries, whole wheat pasta, or another whole grain with your dinner. Read "Health Gains from Whole Grains" for a list of whole grains and their health benefits, or check out thesewhole grain recipes. 

4. Choose whole fruit instead of juice. An orange has two times as much fiber and half as much sugar as a 12-ounce glass of orange juice. I prefer water over everything. I have eliminated ALL juices from my diet.

5. Bring on the beans. Beans are an excellent source of slowly digested carbohydrates as well as a great source of protein.