The Food and Drug Administration (FDA) once insisted that the purgative teas of the most concern are those containing of any of the following elements: aloe, senna, rhubarb root, buckthorn, castor oil and cascara.
These substances are obtained from plants, and they have been widely implemented for many years due to their effectiveness in reducing constipation and helping to facilitate bowel movements. These substances are considered useful for these purposes, but they are applied in rare cases.
It is in the event these teas are consumed more than necessary that serious disorders can occur. Many researches have proven that purgative-induced diarrhea is not effective in reducing absorbed calories because of the fact that purgatives are not operative in the small intestine, where calories are absorbed. In contrast, they operate on the colon, which is at the bottom of the bowel. As a result, the purgative effects of the teas are not very effective at reducing calorie intake.