12 Sep 2007
During daylight hours, green leaves take up carbon dioxide from the air (put there when we breathe). At night the leaves produce oxygen as wells as sugars and starches plus cellulose matter that helps the plants stand up and grow larger.
Without this process throughout the plant kingdom, there would be no natural sugars and starches. We would have to obtain energy from protein or fat.
You'll understand, as you learn more about nutrition, that all life-preserving processes and substances cannot survive without each other. Protein is needed to grow new tissue. Fat provides fat-soluble vitamins and protection as well as energy. So the cycle goes. All processes and portions serve one another.
Carbohydrates provide about half the caloric energy intake for most Americans. In Oriental cultures, carbohydrates provide about four-fifths of the calories(or energy). Americans eat more meat. The energy for us comes from starches and sugars.