PURPOSE: Hypoxia has been shown to reduce energy intake and lead to weight loss, but the underlying mechanisms are unclear. The aim was therefore to assess changes in eating after rapid ascent to 4,559 m and to investigate to what extent hypoxia, acute mountain sickness (AMS), food preferences and satiation hormones influence eating behavior. METHODS: Participants (n = 23) were studied at near sea level (Zurich (ZH), 446 m) and on two days after rapid ascent to Capanna Margherita (MG) at 4,559 m (MG2 and MG4). Changes in appetite, food preferences and energy intake in an ad libitum meal were assessed. Plasma concentrations of cholecystokinin, peptide tyrosine-tyrosine, gastrin, glucagon and amylin were measured. Peripheral oxygen saturation (SpO(2)) was monitored, and AMS assessed using the Lake Louis score. RESULTS: Energy intake from the ad libitum meal was reduced on MG2 compared to ZH (643 ± 308 vs. 952 ± 458 kcal, p = 0.001), but was similar to ZH on MG4 (890 ± 298 kcal). Energy intake on all test days was correlated with hunger/satiety scores prior to the meal and AMS scores on MG2 but not with SpO(2) on any of the 3 days. Liking for high-fat foods before a meal predicted subsequent energy intake on all days. None of the satiation hormones showed significant differences between the 3 days. CONCLUSION: Reduced energy intake after rapid ascent to high altitude is associated with AMS severity. This effect was not directly associated with hypoxia or changes in gastrointestinal hormones. Other peripheral and central factors appear to reduce food intake at high altitude. DOI: https://doi.org/10.1007/s00394-012-0366-9Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-62402 Accepted Version Originally published at: Aeberli, Isabelle; Erb, Annina; Spliethoff, Kerstin; Meier, Daniela; Götze, Oliver; Frühauf, Heiko; Fox, Mark; Finlayson, Graham S; Gassmann, Max; Berneis, Kaspar; Maggiorini, Marco; Langhans, Wolfgang; Lutz, Thomas A (2013). Disturbed eating at high altitude: influence of food preferences, acute mountain sickness and satiation hormones. European Journal of Nutrition, 52 (2) Purpose Hypoxia has been shown to reduce energy intake and lead to weight loss, 36 but the underlying mechanisms are unclear. The aim was therefore, to assess 37 changes in eating after rapid ascent to 4559 m and to investigate to what extent 38 hypoxia, acute mountain sickness (AMS), food preferences, and satiation hormones 39 influence eating behavior. 40Methods Participants (n=23) were studied at near sea level (Zurich (ZH), 446 m) and 41 on two days after rapid ascent to Capanna Margherita (MG) at 4559 m (MG2 and 42 MG4). Changes in appetite, food preferences and energy intake in an ad libitum meal 43were assessed. Plasma concentrations of cholecystokinin, peptide tyrosine-tyrosine, 44 gastrin, glucagon and amylin were measured. Peripheral oxygen saturation (SpO2) 45 was monitored and AMS assessed using the Lake Louis score. 46Results Energy intake from the ad...

BACKGROUND AIMS It is not clear how rapid ascent to high altitude causes the gastrointestinal symptoms of acute mountain sickness (AMS). We assessed the incidence of endoscopic lesions in the upper gastrointestinal tract in healthy mountaineers after rapid ascent to high altitude, their association with symptoms, and their pathogenic mechanisms. METHODS In a prospective study, 25 mountaineers (10 female; mean age, 43.8y±9.5 y) underwent unsedated, transnasal esophago-gastroduodenoscopy in Zurich (490 m) and then on 2 test days (days 2 and 4) at a high altitude laboratory in the Alps (Capanna Regina Margherita, 4559 m). Symptoms were assessed using validated instruments for AMS (the AMS-C and the Lake Louise scoring system) and visual analogue scales (0-100). Levels of mRNAs in duodenal biopsies were measured by qPCR. RESULTS The follow-up endoscopy at high altitude was performed in 19/25 patients on day 2 and in 23/25 patients on day 4. Frequency of endoscopic lesions increased from 12% at baseline to 26.3% on day 2 and 60.9% on day 4 (P<0.001). The incidence of ulcer disease increased from 0 at baseline to 10.5% on day 2 and 21.7% on day 4 (P=.014). Mucosal lesions were associated with lower hunger scores (37.3 vs. 67.4 in patients without lesions; P=.012). Subjects with peptic lesions had higher levels of HIF2A mRNA, which encodes a hypoxia-induced transcription factor, and ICAM1 mRNA, which encodes an adhesion molecule, compared with subjects without lesions (fold changes: 1.38 vs 0.63; P=.001 and 1.37 vs 0.66; P=.011). CONCLUSIONS In a prospective study of 25 mountaineers, fast ascent to high altitude resulted in rapid onset of clinically meaningful mucosal lesions and ulcer disease. Duodenal biopsies from these subjects had increased levels of HIF2A mRNA and ICAM1 mRNA, which might contribute to formation of hypoxia-induced peptic lesions. Further studies are needed of the mechanisms of this process.

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