title: Variation in gastric pH may determine kiwifruit's effect on functional GI disorder: an in vitro study.
abstract: Consumption of kiwifruit is reported to relieve symptoms of functional gastrointestinal (GI) disorder. The effect may be related to the proteases in kiwifruit. This in vitro study aimed to measure protein hydrolysis due to kiwifruit protease under gastric and duodenal conditions. A sequence of experiments incubated meat protein, with and without kiwifruit, with varying concentrations of pepsin and hydrochloric acid, at 37 °C for 60 min over the pH range 1.3-6.2 to simulate gastric digestion. Duodenal digestion was simulated by a further 120 min incubation at pH 6.4. Protein digestion efficiency was determined by comparing Kjeldahl nitrogen in pre- and post-digests. Where acid and pepsin concentrations were optimal for peptic digestion, hydrolysis was 80% effective and addition of kiwifruit made little difference. When pH was increased to 3.1 and pepsin activity reduced, hydrolysis decreased by 75%; addition of kiwifruit to this milieu more than doubled protein hydrolysis. This in vitro study has shown, when gastric pH is elevated, the addition of kiwifruit can double the rate of hydrolysis of meat protein. This novel finding supports the hypothesis that consumption of kiwifruit with a meal can increase the rate of protein hydrolysis, which may explain how kiwifruit relieves functional GI disorder.
authors.affiliation: Faculty of Health and Environmental Sciences, AUT University, Private Bag 92006, Auckland 1142, New Zealand. bruce.donaldson@aut.ac.nz.
authors.forename: Bruce
authors.initials: B
authors.lastname: Donaldson
authors.affiliation: Faculty of Health and Environmental Sciences, AUT University, Private Bag 92006, Auckland 1142, New Zealand. elaine.rush@aut.ac.nz.
authors.forename: Elaine
authors.initials: E
authors.lastname: Rush
authors.affiliation: Faculty of Health and Environmental Sciences, AUT University, Private Bag 92006, Auckland 1142, New Zealand. owen.young@aut.ac.nz.
authors.forename: Owen
authors.initials: O
authors.lastname: Young
authors.affiliation: Institute of Food, Nutrition and Human Health, Albany Campus, Massey University, Auckland 0745, New Zealand. Ray.winger@btconnect.com.
authors.forename: Ray
authors.initials: R
authors.lastname: Winger
mesh_terms: D029042:Actinidia / Q000737:chemistry*; D000818:Animals; D002417:Cattle; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D005638:Fruit / Q000737:chemistry*; D005767:Gastrointestinal Diseases / Q000178:diet therapy*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008460:Meat; D008954:Models, Biological; D010447:Peptide Hydrolases / Q000378:metabolism
chemical_list: D004044:Dietary Proteins; D010447:Peptide Hydrolases
references.citation: Am J Physiol. 1997 Jan;272(1 Pt 2):R243-8
references.pmid: 9039015
references.citation: Gut. 2008 Mar;57(3):298-305
references.pmid: 17965056
references.citation: Best Pract Res Clin Gastroenterol. 2009;23(6):805-19
references.pmid: 19942159
references.citation: Eur J Clin Pharmacol. 2008 Oct;64(10):935-51
references.pmid: 18679668
references.citation: J Appl Microbiol. 2000 Dec;89(6):935-43
references.pmid: 11123466
references.citation: Postgrad Med J. 2007 Jan;83(975):44-53
references.pmid: 17267678
references.citation: Am Fam Physician. 1998 Sep 15;58(4):907-14
references.pmid: 9767726
references.citation: Int J Cancer. 2011 Apr 1;128(7):1652-8
references.pmid: 20503273
references.citation: World J Gastroenterol. 2007 Sep 21;13(35):4771-5
references.pmid: 17729399
references.citation: Am J Med. 2009 Oct;122(10):896-903
references.pmid: 19786155
references.citation: Br J Nutr. 2010 Aug;104(3):374-81
references.pmid: 20307348
references.citation: J Biol Chem. 1972 Jul 25;247(14):4628-32
references.pmid: 4557848
references.citation: Dig Dis Sci. 1991 Jul;36(7):866-9
references.pmid: 2070698
references.citation: J Agric Food Chem. 2010 Apr 28;58(8):5068-73
references.pmid: 20232890
references.citation: Neurogastroenterol Motil. 2009 Jul;21(7):725-e42
references.pmid: 19344341
references.citation: Asia Pac J Clin Nutr. 2010;19(4):451-7
references.pmid: 21147704
references.citation: Curr Gastroenterol Rep. 2010 Aug;12(4):242-8
references.pmid: 20582743
references.citation: Br J Nutr. 2008 Jul;100(1):130-7
references.pmid: 18279548
references.citation: Nutrients. 2011 May;3(5):574-603
references.pmid: 22254112
references.citation: Curr Gastroenterol Rep. 2010 Dec;12(6):448-57
references.pmid: 20882439
references.citation: Aliment Pharmacol Ther. 2005 Aug;22 Suppl 1:55-63
references.pmid: 16042660
references.citation: Asia Pac J Clin Nutr. 2002;11(2):164-8
references.pmid: 12074185
references.citation: J Gastroenterol Hepatol. 2011 Apr;26 Suppl 3:15-8
references.pmid: 21443701
references.citation: Mol Nutr Food Res. 2009 Aug;53(8):952-8
references.pmid: 19603399