No source was found, from any airline, catering company, aviation regulator, food safety regulator, or peer-reviewed literature, stating or documenting that in-flight meals contain an ingredient added for the purpose of causing constipation. No named additive, no supplier, no internal document, and no whistleblower account surfaced across twelve searches.

The identical claim exists in a parallel domain and has been officially addressed there. A U.S. Army field nutrition training document lists, among beliefs soldiers hold about combat rations, the idea that rations are "designed to cause constipation to keep from having to go to the bathroom while on a mission" and that the gum is a laxative, and the instructor guidance states plainly: "These are myths. Most of what people say about MREs is not accurate." Reporting on the same subject quotes the Army Natick Soldier Systems Center public affairs chief confirming the gum in MREs is not a laxative but a gum containing xylitol, included for oral health and hygiene in the field .

A genuinely analogous practice does exist, but in spaceflight, not commercial aviation. To reduce bowel movements, astronauts used a high-protein, low-residue diet consisting of foods that produce relatively little waste after absorption , and before physically demanding spacewalks astronauts have historically limited food intake or eaten a low-residue diet, which reduced their work performance and posed a health risk . This is dietary composition management for a specific operational reason, not a constipating additive, and it applies to astronauts, not airline passengers.

What airline caterers are documented as adding is unrelated to bowel function. Because taste perception is dulled in a pressurized cabin, catering companies add extra fat, salt, and sugar . On the industry side, one low-authority commentary claims in-flight menus exclude gas-producing items such as onions, garlic, legumes and high-fibre foods because they cause intestinal gas and stomach bloat . If accurate, the stated rationale is passenger comfort and bloating at altitude, not blocking defecation, and this source is not authoritative enough to treat as established industry policy.

There is a well-documented ordinary explanation for the underlying sensation. Cabins are pressurized to an equivalent altitude of several thousand feet, and this reduced cabin pressure causes gases in body cavities to expand . Dietitians quoted in travel coverage attribute in-flight digestive sluggishness to low fibre intake, noting that when insufficient fibre is consumed the body does not move waste through as frequently, which can contribute to constipation , and recommend increasing fibre and fluids to stay regular.