I felt uncertain about using the phrase in what I wrote so far, but all I had for source was the clipping. Glucose is the sugar stored in the liver for food energy, and is the principal energy-providing nutrient of body cells. Nerve cells and brain cells rely entirely on glucose for their food source. Actually, all sugars, simple and complex, are carbohydrates. When you string sugar molecules into a long enough chain, you get cellulose, which makes up the tough, stringy tissue of plants.
Wood fiber is mostly cellulose, that is, very long sugar molecules.
Cows and termites can digest cellulose. We can digest some of them, too, if we cook them to break them down into starches and sugars. People get their best nutrition from starches, found in wheat, rice, potatoes, and most other vegetable products. Actually, meat contains a high percentage of carbohydrates as well as protein.