Gastric emptying effects of dietary fiber during 8 hours at two simulated cabin altitudes.
BACKGROUND
In a questionnaire survey, long-distance flying staff of a charter airline reported significantly more dyspeptic symptoms than did short-haul crewmember and ground personnel (belching: 57% vs. 37%, bloating: 51% vs. 36%). To elucidate the reason for increased frequency of gastrointestinal symptoms during long-distance flights, we investigated the effects of altitude and diet on gastric emptying, cardiovascular function, and bodily complaints.


METHODS
In a 2 x 2 repeated measurement design we simulated an 8-h flight in a hypobaric chamber in 16 healthy men subjected to 2 meal conditions (high fiber vs. low fiber) on separate days, and assigned to either a flight altitude of 2500 m (8200 ft) or 1000 m (3280 ft). The subjects were blinded toward altitude. Heart rate and gastrointestinal symptoms were taken every hour, and gastric emptying was assessed by 13C-octanoic acid breath-test. In a separate experiment, we examined the effect of the two test meals (2 g vs. 20 g of fiber) in 30 healthy men under conventional laboratory conditions and found no significant differences.


RESULTS
At an altitude of 2500 m, heart rate was significantly increased independent of the dietary condition. Gastric emptying (T1/2) was significantly delayed at 2500 m (8200 ft) when a high-fiber meal was given (146.3 +/- 58.4 min low fiber vs. 193.9 +/- 54.3 min high fiber). The symptom score for gastric distension (mean: 1.33 +/- 0.3 vs. mean: 1.07 +/- 0.15) and bloating (mean: 1.82 +/- 0.47 vs. mean: 1.34 +/- 0.35) were also significantly increased at 2500 m for the high-fiber meal compared with the low-fiber meal.


CONCLUSIONS
Flight altitude is a physiological load. In combination with a high-fiber diet, this induces significant delays in gastric emptying that may explain symptoms of cabin and cockpit crew and passengers on long-distance flights.
Hinninghofen
Heidemarie
H
Internal Medicine VI, Psychosomatic Medicine and Psychotherapy, University Hospitals Tübingen, Tübingen, Germany. Heidemarie.Hinninghofen@uni-tuebingen.de
Musial
Frauke
F
Kowalski
Axel
A
Enck
Paul
P
D000328:Adult; D000337:Aerospace Medicine; D000531:Altitude; D000704:Analysis of Variance; D001274:Atmospheric Pressure; D004043:Dietary Fiber / Q000009:adverse effects*; D004415:Dyspepsia / Q000209:etiology*; D005746:Gastric Emptying; D006339:Heart Rate; D006801:Humans; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D012044:Regression Analysis; D016037:Single-Blind Method