This group of vegetables contributes little to the nourishment of man. They are eaten chiefly because of their agreeable flavor and because they add variety to our diet. The amount of protein and fat that they contain is inappreciable, and their carbohydrates are in very small quantities. They possess mineral salts of value and sometimes organic acids. Oxalic acid, which occurs in considerable quantities in some of the green vegetables, makes them harmful to those who are prone to develop oxalic acid calculi. The large amount of cellulose they contain produces bulky feces, but stimulates peristalsis. Many of these vegetables are distinctly laxative. They contain from 80 to 96 per cent, of water, which makes them a bulky form of food. For the most part they must be cooked, a process that softens the cellulose and makes them more digestible. A few are eaten raw. Certain of them cause flatulence; many do not. Cabbages are especially prone to create a condition of flatulence. Green vegetables are antiscorbutics.

Most green vegetables are not sufficiently digestible to be good for invalids. If the functions of the stomach and intestines are not greatly impaired, the blandest can be used. With the exception of lettuce, cabbage and tomatoes they should not be eaten raw. Spinach and celery boiled in milk, if finely chopped, are bland and agreeable. These articles do not ferment in the stomach or bowels to an appreciable extent, and can often be prescribed when other vegetables must be avoided.

Penzoldt found that it required for from two to three hours for the stomach to dipose of 150 grams of boiled cauliflower or asparagus, three to four hours for the same quantity of carrots, kohlrabi, spinach, cucumber salad, and radish. The following table, taken from Hutchison, will give some idea of the composition and food value of this class of foods: