Broadly speaking, plants furnish the carbohydrates, that is, starch and sugar; animals furnish the fats and proteids. 伯莎M.克拉克.科学通论.
The peanut, for example, contains 43% of fat, 30% of proteids, and only 17% of carbohydrates; the Brazil nut has 65% of fat, 17% of proteids, and only 9% of carbohydrates. 伯莎M.克拉克.科学通论.
On the other hand, they are worthless for cell growth and repair, and if we limited our diet to carbohydrates, we should be like a man who had fuel but no engine capable of using it. 伯莎M.克拉克.科学通论.
This class of foods contains carbon, oxygen, and hydrogen, and in addition, two substances not found in carbohydrates or fats--namely, sulphur and nitrogen. 伯莎M.克拉克.科学通论.
When we test fats for fuel values by means of a calorimeter (Fig. 26), we find that they yield twice as much heat as the carbohydrates, but that they burn out more quickly. 伯莎M.克拉克.科学通论.
Corn, wheat, rye, in fact all cereals and grains, potatoes, and most vegetables are rich in carbohydrates; as are also sugar, molasses, honey, and maple sirup. 伯莎M.克拉克.科学通论.
Most of our carbohydrates are of plant origin, being found in vegetables, fruits, cereals, and sirups. 伯莎M.克拉克.科学通论.