Abstract
The current health problems regarding the obesity epidemic, development of type 2 diabetes mellitus (T2D) and cardiovascular disease are a major challenge for healthcare systems worldwide.No simple or unique cure has been documented to prevent or treat this major health problem regarding T2D and the risk factors related to this disease. There is therefore an immediate need for prevention methods and effective approaches to overcome these serious health issues.
It will need a combination of several interventions. The treatment of T2D today is primarily lifestyle changes like increased physical activity and change of diet, which corresponds to the treatment of insulin resistance, IGT and obesity. Secondly, a variety of medicine is used.
Within nutrition, one of the research areas is preventive or therapeutic aims against development of T2D. A better glycaemic control is one preventive target and furthermore it seems to be able to delay the incidence of T2D.Prandial regulation of glucose is a complex process and there are several methods to assess glycaemic control and thereby affect the blood glucose concentration. The prandial glucose regulation depends on factors including physical activity, the nature of ingested food, gastric emptying, intraluminal glucose oncentration, and enzymatic activity in the brush border.
The focus in this review is on evidence provided by in vitro studies, animal models and human studies on Larabinose, D-xylose and polyphenols. The focus is on their effects on carbohydrate- ingesting enzymes activity in vitro and possible effects on human postprandial blood response.
In paper 1 the effects of sugar beet polyphenols from molasses and the potential inhibition of sucrase activity in vitro, was investigated. Two different polyphenol-rich fractions from chromatographic separation of molasses from sugar beets and pure ferulic acid were tested. We found no effects of the two fractions of molasses. The pure ferulic acid indicated an inhibition of sucrase in vitr.
Both in vitro and in vivo studies have investigated the effects of L-arabinose and D-xylose on carbohydrate digestive enzymes.
In paper 3, D-xylose and L-arabinose was investigated in vitro and in vivo. This study found that D-xylose and Larabinose inhibit both sucrase and maltase when tested in a Caco-2 cell model. In addition, 13 healthy subjects completed a randomized double-blinded cross-over study with sucrose drinks supplemented with 4, 8 w/w% xylose or 8 w/w% L-arabinose. This showed that supplementation of 8% D-xylose and L-arabinose compared to pure sucrose produced a decline in blood glucose peak, as well as a decreased and delayed insulin peak.
These results from a sucrose drink added L-arabinose and D-xylose constituted the basis for the further investigations of L-arabinose. However, the use of higher dietary doses of sucrose would be unfeasible in terms of palatability in the human population.
In paper 2, the purpose was to investigate if the positive effects of L-arabinose added to a sugar drink could be reproduced in a mixed meal containing sucrose and/or starch. Furthermore the consistencies of the ingested meals and the possible effect on gastric emptying and thereby postprandial blood concentrations of glucose, insulin and C-peptide, were investigated.
In conclusion, this PhD thesis found no evidence that L-arabinose affects post prandial blood glucose, insulin and C-peptide when mixed in a meal. This might be due to the difference in gastric emptying rate between the fluid and solid meals, but the conclusion is associated with certain reservations regarding sample size (n=6) in the study and the method for measuring gastric emptying.
Furthermore, the fluid maltose drink could not validate the in vitro studies on maltase activity.The overall concluding perspective must be that L-arabinose has the greatest potential to effect glucose and insulin secretion when added to a sucrose drink.
It will need a combination of several interventions. The treatment of T2D today is primarily lifestyle changes like increased physical activity and change of diet, which corresponds to the treatment of insulin resistance, IGT and obesity. Secondly, a variety of medicine is used.
Within nutrition, one of the research areas is preventive or therapeutic aims against development of T2D. A better glycaemic control is one preventive target and furthermore it seems to be able to delay the incidence of T2D.Prandial regulation of glucose is a complex process and there are several methods to assess glycaemic control and thereby affect the blood glucose concentration. The prandial glucose regulation depends on factors including physical activity, the nature of ingested food, gastric emptying, intraluminal glucose oncentration, and enzymatic activity in the brush border.
The focus in this review is on evidence provided by in vitro studies, animal models and human studies on Larabinose, D-xylose and polyphenols. The focus is on their effects on carbohydrate- ingesting enzymes activity in vitro and possible effects on human postprandial blood response.
In paper 1 the effects of sugar beet polyphenols from molasses and the potential inhibition of sucrase activity in vitro, was investigated. Two different polyphenol-rich fractions from chromatographic separation of molasses from sugar beets and pure ferulic acid were tested. We found no effects of the two fractions of molasses. The pure ferulic acid indicated an inhibition of sucrase in vitr.
Both in vitro and in vivo studies have investigated the effects of L-arabinose and D-xylose on carbohydrate digestive enzymes.
In paper 3, D-xylose and L-arabinose was investigated in vitro and in vivo. This study found that D-xylose and Larabinose inhibit both sucrase and maltase when tested in a Caco-2 cell model. In addition, 13 healthy subjects completed a randomized double-blinded cross-over study with sucrose drinks supplemented with 4, 8 w/w% xylose or 8 w/w% L-arabinose. This showed that supplementation of 8% D-xylose and L-arabinose compared to pure sucrose produced a decline in blood glucose peak, as well as a decreased and delayed insulin peak.
These results from a sucrose drink added L-arabinose and D-xylose constituted the basis for the further investigations of L-arabinose. However, the use of higher dietary doses of sucrose would be unfeasible in terms of palatability in the human population.
In paper 2, the purpose was to investigate if the positive effects of L-arabinose added to a sugar drink could be reproduced in a mixed meal containing sucrose and/or starch. Furthermore the consistencies of the ingested meals and the possible effect on gastric emptying and thereby postprandial blood concentrations of glucose, insulin and C-peptide, were investigated.
In conclusion, this PhD thesis found no evidence that L-arabinose affects post prandial blood glucose, insulin and C-peptide when mixed in a meal. This might be due to the difference in gastric emptying rate between the fluid and solid meals, but the conclusion is associated with certain reservations regarding sample size (n=6) in the study and the method for measuring gastric emptying.
Furthermore, the fluid maltose drink could not validate the in vitro studies on maltase activity.The overall concluding perspective must be that L-arabinose has the greatest potential to effect glucose and insulin secretion when added to a sucrose drink.
| Original language | English |
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| Place of Publication | Copenhagen |
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| Publisher | Department of Nutrition, Exercise and Sports, Faculty of Sciences, University of Copenhagen |
| Number of pages | 138 |
| ISBN (Print) | 978-87-7611-638-5 |
| Publication status | Published - 2013 |