Citrucel Powder Orange Flavor Fiber Therapy for Occasional Constipation Relief, 16 ounce Fiber for irregularity that wont cause excess gas. (Based on laboratory testing. Individual results may vary) Clinically proven** effective to relieve occasional constipation Citrucel contains methylcellulose fiber, which is a non-toxic, non-allergenic, and non-irritant fiber Great-tasting orange flavor Contains methylcellulose fiber, a fiber derived from cellulose Available in 16-ounce and 30-ounce powders Citrucel is recommended by physicians (among therapeutic fiber laxatives) ** Snape W. The Effect of Methylcellulose on Symptoms of Constipation. Clinical Therapeutics .1989; Sep-Oct;11(5):572-9.