Laxatives (purgatives, aperients) are foods, compounds, or drugs taken to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and/or bowel examinations, and may be supplemented by enemas under certain circumstances. Sufficiently high doses of laxatives may cause diarrhea. Laxatives work to increase the movement of feces along the colon. Some laxatives combine more than one active ingredient. Laxatives may be oral or in suppository form. Foods that help with laxation include fruits, especially kiwifruit and prunes, bran products, aloe vera, blackstrap molasses, and nuts (especially almonds and walnuts).