Let’s take a closer look at carbohydrates to get a better understanding of what they are and how they impact the human body. A carbohydrate is a large biological molecule, or macromolecule, consisting of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a hydrogen:oxygen atom ratio of 2:1 (as in water). The carbohydrates (saccharides) are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. The monosaccharides and disaccharides, which are smaller (lower molecular weight) carbohydrates, are commonly referred to as sugars. While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end in the suffix -ose. For example, grape sugar is the monosaccharide glucose, cane sugar is the disaccharide sucrose, and milk sugar is the disaccharide lactose. Oligosaccharides contain a small number (typically three to nine simple sugars (monosaccharides) and can have many functions including being one of the components of fiber, found in plants. Polysaccharides contain more than ten monosaccharide units with examples including storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose and chitin.
In food science and in many informal contexts, the term carbohydrate often means any food that is particularly rich in the complex carbohydrate starch (such as cereals, bread, tubers and pasta) or simple carbohydrates, such as sugar (found in candy, jams, and desserts). Carbohydrates are a common source of energy in living organisms.
“Carbohydrates are the body’s most efficient way to get everything it needs. Produced by plants through photosynthesis, carbohydrates are made from compounds of carbon, hydrogen and oxygen called sugars or saccharides. Molecules of these simple sugars attach together to make long branching chains called complex carbohydrates. These large carbohydrate molecules are commonly referred to as starch.
When eaten, enzymes disassemble these chains back into the simple sugars. These simple sugars then pass easily through the intestinal wall into the bloodstream for distribution to all the cells in your body. Metabolic processes change these simple sugars into energy.
Dietary fibers are even longer chains of complex carbohydrates – so complex that they don’t get entirely digested. Most fibers eventually end up in the colon and form the bulk of your stool. Many people think fibers are only the husks of grains and the long stringy components in fruits and vegetables, but dietary fibers are present in all plant tissues. Even peeled potatoes, for example, contain lots of fiber.
Carbohydrates are made by plants and stored in their leaves, stems, roots and fruits. Plant foods contain both simple and complex carbohydrates in various amounts. Fruits are often more than 90 percent carbohydrate, but most of their carbohydrates are the sweet-tasting simple forms of carbohydrate, such as glucose and fructose. Green and yellow vegetables store most of their calories as complex carbohydrates, but since they contain very few total calories, the amount of complex carbohydrate they provide in the diet is small. Whole grains (rice and corn), whole grain flours (wheat and rye, as well as whole grain pastas made from them, such as wheat and soba noodles), tubers (potatoes and yams), legumes (beans and peas), and winter squashes (acorn and hubbard) contain large quantities of complex carbohydrates and thus are known as starches. Rice, corn, and other grains, as well as potatoes, typically store about 80 percent of their calories in the form of complex carbohydrates. Beans, peas, and lentils are approximately 70 percent complex carbohydrates.
Starches contain sufficient calories to easily meet the energy requirements of an active person, and they’re also abundant in essential amino acids (from proteins), essential fats, fibers, and minerals. Many starches, such as the much-maligned potato, have a full complement of vitamins as well, whereas grains and legumes need the help of fruits or green and yellow vegetables in order to provide adequate vitamin A and C.
You’ve probably heard that marathon runners and other endurance athletes “load up” on carbohydrates before an event in order to store energy-providing carbohydrates for the long race. They do this because it works. Loading up on carbohydrates several times a day will give you the energy to race through your busy life.
The only food from animals in which a carbohydrate is found in significant amounts is milk which contains a simple sugar called lactose, but lactose can’t be digested by most adults, and consequently, can cause assorted evidences of indigestion, such as diarrhea, stomach cramps, and hurtful amounts of gas.
In general, Americans eat far too few calories from carbohydrates – only about 40%. To make things worse, the kinds of carbohydrates eaten most commonly are “empty calories” in the form of white sugar, corn syrup, and fructose. A healthy diet, like the McDougall diet, is closer to 80% carbohydrate from nutritious foods: starches, vegetables and fruits.”(1)
A Lesson in Nutrition, Dr. McDougall’s Health and Medical Center