Carbohydrates are molecules composed of carbon, hydrogen, and oxygen that all plant foods (beans, grains, fruits, vegetables, etc) contain. There are four different types of carbs, which all serve a certain purpose:

“Simple Sugars:” Monosaccharides and Disaccharides : The simplest forms of carbohydrates, simple sugars are immediate sources of energy. All other forms of energy (fat, protein, starch, complex carbs) need digestive enzymes in the stomach to break them down before they’re converted to energy for our cells. Sugar enters our blood stream as soon as it dissolves in our saliva. (This can be useful when running a marathon or riding a bike, since our body doesn’t have the energy to digest, but needs the calories.)

What kinds of foods constitute simple sugars? Many foods contain sugar (even milk, which contains lactose), but pure simple sugar is usually extracted from a whole food (except honey.) “Concentrated fruit syrup,” table sugar, brown rice syrup, maple syrup, etc., are almost pure sugar. Many foods contain sugars, but most of them contain fiber, protein, and/or fat as well, so the sugar will not absorb into the body as quickly.

The prebiotic: Oligosaccharides: Oligosaccharides are carbohydrates made up of 3-10 simple sugars linked together, and humans cannot fully digest them. That can actually be beneficial…the undigested bits serve as food for intestinal microflora, (bacteria in our gut!)

What kinds of foods contain oligosaccharides? They are found in plants in small amounts. Chicory root and Jerusalem artichokes contain the highest amount, but they’re also found in: wheat, jicama, the onion family, asparagus, burdock root, and other plants.

“Complex Carbs,” Polysaccharides: “Complex Carbs” release their energy more slowly than simple sugars, since it takes longer for our bodies to break them down. This causes a less severe spike in blood sugar, and gives your body more time to “burn off” or “use” the energy. The scientific definition of polysaccharides is a chain of monosaccharaides (sugars) linked together by glycosidic bonds. There are different kinds of polysaccharides, which are “structure” or “storage” related:

Starch: Starch is the way that plants store excess glucose (energy). Almost all vegetables and grains contain starch in varying degrees-common food sources include potatoes, wheat, rice, corn, taro root, yams, cassava, barley, and rye.

Fiber (or Cellulose): Cellulose is supposedly the most abundant substance in the living world. It is present in almost all plant foods. Cellulose is classified as “dietary fiber.” It is actually indigestible to humans and most animals. (For instance, wood, cotton and paper are almost pure cellulose.) That may seem odd, since fiber is supposed to be good for us. But it’s indigestibility is actually its function…it changes the nature of our digestive tract, binds to bile acids to lower cholesterol, and changes how nutrients and chemicals react in the intestines. Fiber is extremely important, and I will devote an entire blog post to explain it.

Glycogen: Humans store “extra” energy in their livers and muscles in the form of glycogen. It is a kind of carbohydrate that can be broken down in glucose, or blood sugar, when the body has been deprived of food. All the glycogen in our bodies can be used up in one 24-hour period of fasting, or an intense workout. Luckily, it is replenished by the ingestion of carbohydrates.

There are other forms of fiber (structural polysaccharides) such as chitin, the compound that shellfish exoskeletons are made from, or pectin, a form of soluble fiber found in fruits.  Most plant foods contain a combination of starch and fiber, and humans have consumed these foods throughout history, (although the amount we should consume is a hot debate). I will bring in anthropology sources as a response to that question in a later post….