The skins of fruit are of this nature and may often be eaten, as in case of prunes, figs, apples, dried peaches and apricots.

The outer coats of grains, which serve the same purpose, are frequently removed by milling, but similar coats of peas and beans are not so removed except in the case of dried split peas.

In the juices of fruits and vegetables we find a variety of laxative substances.

This explains why apple juice (sweet cider), orange juice or diluted lemon juice may be a very desirable morning drink.

The effect is partly due to the acid but not wholly.