Insight on Glucose and Fructose Absorption and Relevance in the Enterocyte Milieu.

Elena Chiarello,Gianfranco Picone,Giorgia Antonelli,Alessandra Bordoni,Francesco Capozzi,Mattia Di Nunzio

doi:10.3390/nu14030517

Elena Chiarello, Gianfranco Picone + Show 4 more

Open Access

https://doi.org/10.3390/nu14030517

Copy DOI

Abstract

Although epidemiological studies indicate a strong correlation between high sugar intake and metabolic diseases, the biological mechanisms underlying this link are still controversial. To further examine the modification and crosstalk occurring in enterocyte metabolism during sugar absorption, in this study we evaluate the diffusion and intestinal metabolism of glucose, fructose and sucrose, which were supplemented in equimolar concentration to Caco-2 cells grown on polyester membrane inserts. At different time points after supplementation, changes in metabolite concentration were evaluated in the apical and basolateral chambers by nuclear magnetic resonance (NMR) and gas-chromatography (GC). Sucrose was only minimally hydrolyzed by Caco-2 cells. Upon supplementation, we observed a faster uptake of fructose than glucose, the pentose sugar being also faster catabolized. Monosaccharide absorption was concomitant to the synthesis/transport of other metabolites, which occurred differently in glucose and fructose supplemented cells. Our results confirm the prominent role of intestinal cells in fructose metabolism and clearance after absorption, representing a further step forward in the understanding of the role of dietary sugars. Future research, including targeted analysis on specific transporters/enzymes and the use of labeled substrates, will be helpful to confirm the present results and their interpretation.

Highlights

Publisher’s Note: MDPI stays neutralGlucose (GLU) and fructose (FRU) are the main monosaccharides in the human diet.FRU and GLU share the same molecular formula (C6 H12 O6 ) and energy value (4 kcal/g), but have different sweetening power and glycemic index [1], satiating capacity [2], absorption mechanism [3], and metabolism once absorbed, and within the intestinal cell [4]
methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and light microscopy examination did not evidence either modification in cell viability or in monolayer integrity at any time point
Notwithstanding the more efficient diffusion of FRU than GLU, at T8, the basolateral chambers (BLC) concentration of the supplemented monosaccharide was similar in the two experimental conditions, suggesting that FRU was only partially released in the BLC in its parent form, and was it actively metabolized within the cell

Summary

Introduction

Glucose (GLU) and fructose (FRU) are the main monosaccharides in the human diet. FRU and GLU share the same molecular formula (C6 H12 O6 ) and energy value (4 kcal/g), but have different sweetening power and glycemic index [1], satiating capacity [2], absorption mechanism [3], and metabolism once absorbed, and within the intestinal cell [4]. The classical mechanism for intestinal glucose absorption involves uptake across the apical membrane of enterocytes via sodium-glucose co-transporter 1. It has been recognized that the apical uptake phase has two distinct elements: a saturable, phloridzin-sensitive fraction (SGLT1) and a diffusive component, suggesting that more than one transporter may be involved. Studies have revealed that glucose transporter 2 (GLUT2) is expressed at the apical membrane of enterocytes with regard to jurisdictional claims in published maps and institutional affiliations

Objectives

Results

Discussion

Conclusion