Variation in gastric pH may determine kiwifruit's effect on functional GI disorder: an in vitro study.

Bruce Donaldson,Owen Young,Ray Winger,Elaine Rush

doi:10.3390/nu6041488

Bruce Donaldson, Owen Young + Show 2 more

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https://doi.org/10.3390/nu6041488

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Journal: Nutrients	Publication Date: Apr 11, 2014
Citations: 34	License type: CC BY 4.0

Affiliation: Auckland University of Technology

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.

Highlights

Clinical evidence [1] supports the hypothesis that for some people, consumption of kiwifruit (Actinidia deliciosa, Hayward variety) relieves symptoms of gastrointestinal (GI) disorder such as indigestion, bloating and constipation
kiwifruit enzyme (KF) was essentially inactive under these conditions
The magnitude of the total effect on protein hydrolysis is not reported, the digestion of Troponin T was increased by 15%

Summary

Introduction

Clinical evidence [1] supports the hypothesis that for some people, consumption of kiwifruit (Actinidia deliciosa, Hayward variety) relieves symptoms of gastrointestinal (GI) disorder such as indigestion, bloating and constipation. Occurring more frequently with ageing [2], constipation, a symptom of functional GI disorder [3], has a multifactorial etiology including enforced immobility, autoimmune responses, microbial influx, inflammatory bowel disease, a change of diet or an unbalanced diet, and some forms of medication (including analgesics, antibiotics and chemotherapeutics) [4]. It is common practice in both New Zealand hospitals and elder care homes to administer Kiwifruit juice in the form of Kiwi CrushTM to relieve and prevent constipation. A hospital audit has shown the efficacy of inclusion of kiwifruit in the diet for the management of functional GI disorder [8]

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