Its ingredient was guar gum, a soluble fiber used in small amounts as a thickener in sauces, desserts, syrups, and various other foods. Guar gum has some medically recognized value as a bulk laxative, a cholesterol-lowering agent, and an adjunct to controlling blood sugar levels in certain diabetics. But it has not been proven effective for weight control. When taken by mouth, guar gum forms a gel within the stomach that may contribute to a feeling of fullness and block absorption of a few nutrients. However, neither of these characteristics is enough to produce weight loss.
Many overweight people keep eating even when their stomach signals that it is full.
Moreover, if food absorption is decreased, the individual may eat more to compensate. But Cal-Ban tablets were not merely ineffective. When placed in water, they would swell to four or five times their original size and assume the consistency of putty. The U.S. Food and Drug Administration collected reports of at least 17 cases of esophageal obstruction among Cal-Ban users. Hospital stays were required by ten of these people, one of whom died.