Abdominal x-ray as a scout film for other procedures such as barium enemas. An upper gastrointestinal series is where a contrast medium, usually a radiocontrast agent such as barium sulfate barium salt mixed with water, is ingested or instilled into the gastrointestinal tract, and X-rays are used to create radiographs of the regions of interest. The barium enhances the visibility of the relevant parts of the gastrointestinal tract by coating the inside wall of the tract and appearing white on the film. A lower gastrointestinal series is where radiographs are taken while barium sulfate, a radiocontrast agent, fills the colon via an
Colon cleansing support, "auto-intoxication" persists in the public imagination. The practice of colon cleansing has undergone a resurgence in the alternative-medical community, supported by testimonials and anecdotal evidence and promoted by manufacturers of colon-cleansing products. In the United States the Food and Drug Administration (FDA) regulates the production of equipment used in colon hydrotherapy in the USA but does not regulate their use, or the supplements used in oral colon-cleansing regimens and manufacturer claims do not require verification or supporting evidence. The contents of the products are also not verified or tested. The FDA has issued several letters warning manufacturers and suppliers