Fiber adverse reactions and interactions.
Dry natural powdered fibers are generally safe when mixed with adequate water or another liquid, but these are not without health risks. At least 8 ounces of fluid is recommended when taking dry fibers such as glucomannan, Konjac root, guar gum, Citrucel, and psyllium (Metamucil). Health Canada issued a warning that glucomannan fiber caused choking, obstruction of the throat, esophagus or bowels according to reports when not consumed with adequate amount of fluid (54). The warning also stated that the fiber should not be taken before bed. Fibers may also bind medications and interfere with absorption resulting in a reduction in the desired effect of the medication. Therefore, it may be best to take medications 2 hours before or after the fiber is taken.