A bezoar \ˈbē-ˌzō(ə)r \ is a hard solid mass of indigestible material that can build up over time and possibly cause an obstruction. Bezoars can be classified into four types depending on the type of material swallowed. Trichobezoars \ˌtrik-ō-ˈbē-ˌzō(ə)rz \ are composed of hair and are most commonly associated with patients who have a psychiatric disorder. Pharmacobezoars \ˌfärmə kō- bē-ˌzō(ə)rz\ are composed of undigested medication. Lactobezoars \ˌlaktō- bē-ˌzō(ə)rz \ are more commonly seen in neonates and are comprised of milk curd. The bezoar associated with gastric bypass is a post-operative complication called a phytobezoar \ˌfīt-ō-ˈbē-ˌzō(ə)r \. Phytobezoars \ˌfīt-ō-ˈbē-ˌzō(ə)rz \ are composed of undigested fiber from certain vegetables and fruits such as corn and grape skins. A gastric bypass patient’s stomach pouch is approximately the size of a golf ball. The outlet (or stoma) created in the stomach pouch is about the size of an M&M. The food a person eats must be able to pass through this narrow opening, which is why food must be chewed over and over. Patients heal at different rates and scar differently. For some patients, scarring at the pouch’s outlet can make this M&M-size passageway even narrower. This is a complication that a person cannot control. In the Roux-en-Y gastric bypass, a special type of cutting stapler is used when the stomach is divided to create the stomach pouch. This stapler is also used to divide the small intestine. As healing progresses over the first three to four weeks after surgery, scar tissue grows over the staples. If forbidden foods such as raisins are eaten before this stapled area is healed, it may lead to an obstruction. In the short-term, avoid foods like dried fruits, seeds, and nuts until one's staples are covered with scar tissue. Long-term, be mindful of foods such as corn or grapes which could create a phytobezoar \ˌfīt-ō-ˈbē-ˌzō(ə)r \. I had fun researching bezoars. I hope this helps even one person to make wiser -- and safer -- food choices.