What are Carbohydrates?

Carbohydrates are sugars, starches and fibers. Carbohydrates are often called simple carbohydrates and complex carbohydrates. The simple carbohydrates are sugars known as monosaccharides and disaccharides. The complex carbohydrates are the polysaccharides known also as starches and fibers. Almost all foods contain some carbohydrates. The best sources of carbohydrates are grains, legumes, tubers and root vegetables.

Grains include: barley, bulgar (cracked wheat), farro, spelt, sorghum, corn, millet, rice, rye, wheat, triticale, kamut, amaranth, buckwheat, quinoa and oats

Legumes include: lima beans, black beans, blackeye beans, garbanzo beans, Great Northern beans, Navy beans, Pink beans, Pinto beans, Red Kidney beans, peas, and lentils

Tubers include: potatoes, carrots, turnips, beats and parsnips

Root Crops include: yams, cassavas

Simple Sugars

Monosaccharides are single sugars. Glucose, Fructose, and Galactose are all single sugars. All monosaccharides come from of the four main types of atoms found in foods- hydrogen, oxygen, and carbon. All monosaccharides important in nutrition have the same numbers and kinds of atoms but they are arranged differently. Fructose is the sweetest tasting, followed by glucose. Galactose does not taste very sweet.



Glucose is also known as blood sugar. Glucose is the necessary energy source for the body’s activities. All digested carbohydrates are digested and broken down into glucose to be used by the body for energy.


Fructose has exactly the same chemical formula as glucose but its chemical structure is slightly different. Fructose occurs naturally in fruits. High fructose corn syrup is a syrup made from cornstarch that has been treated with an enzymes. The enzymes convert some of the glucose to a much sweeter fructose. High fructose corn syrup is used in processed foods and beverages.


Galactose is a monosccharide that occurs naturally only in a few foods. Galactose has the same number and kinds of atoms as glucose and fructose but are arranged in yet another form


Disaccharides are two monosaccharides linked together. The monosaccharide glucose is part of all three disaccharides. Maltose is a disaccharide consisting of two glucose units. Maltose is produced whenever starch is broken down during digestion. Sucrose is a disaccharide composed of a fructose and glucose unit linked together. Sucrose is naturally sweet. Sucrose gives fruits, vegetable and grains sweetness. Table sugar is sucrose refined from the juices of sugarcane or sugar beets and then granulated. Lactose is a disaccharide composed of a glucose and galactose combination. Lactose is the main source of carbohydrate from milk.

Maltose-2 glucose units
Sucrose-1 fructose and 1 glucose unit
Lactose-1 galactose and 1 glucose unit

Complex Carbohyrdates

Complex carbohydrates are chains of monosaccharides called polysaccharides. Polysaccharides are classed into three categories: Glycogen, Starches, and Fibers.

Glycogen are long chains of glucose molecules stored in the human body. The storage of glucose when signaled can be quickly broken down for energy by enzymes.

Starches are long chains of glucose molecules found in plant sources. During digestion the longs chains are broken down in the body.

Fibers are mainly polysaccharides. The difference between starches and fibers is that humans do the have the enzymes available to break down the bonds between most fibers. Some fibers are digested by the normal bacteria found in the gastrointestinal tract.