Nutrient-extraction blender preparation reduces postprandial glucose responses from fruit juice consumption

K M Redfern,M A Jarvis,N Sweet,V L Cammack,G A Rees,L A Preston

doi:10.1038/nutd.2017.36

Abstract

Although whole-fruit consumption is regarded as protective against type 2 diabetes (T2DM), conventionally prepared fruit juice is associated with increased T2DM risk, and current public health advice recommends its restriction. ‘Nutrient extractor’ style blenders are increasing in popularity worldwide as an alternative means of juicing fruit, but little is known about their effect on postprandial glucose levels. The current study investigated the effect of nutrient extraction on postprandial blood glucose response and glycemic index (GI) compared with a glucose control for both mixed fruit and a high GI fruit (mango). Remarkably, consumption of nutrient-extracted mixed fruit resulted in a significant lowering of the GI (32.7±8.5) compared with whole mixed fruit (66.2±8.2, P<0.05). For the high GI mango, there were no differences between nutrient-extracted and whole fruit, indicating that even for a high GI fruit the effect of nutrient extraction does not increase GI compared with the whole fruit. These findings suggest that, in contrast to conventionally prepared fruit juice, fruit juice prepared by nutrient extraction in some cases elicits a more favorable postprandial glycemic response than whole fruit and even for high GI fruits do not worsen the response. The mechanism responsible for this effect is currently unclear. However, these results suggest that fruit homogenized by nutrient extraction should be considered as a potential dietetic strategy for glycemic control.

Highlights

Increased fruit consumption is associated with the lowering of risk from multiple chronic diseases;[1] and public health campaigns worldwide consistently aim to promote awareness of the positive health effects of fruit
Results from our study indicated that nutrient extraction of fruit has the potential to significantly lower its glycemic index (GI)
The effect of nutrient extraction resulted in a lowered GI response even than consumption of the corresponding whole fruit, with whole fruit being associated with a medium GI between 55 and 69, whereas the nutrient-extracted fruit juice had a low GI ⩽ 55.11 the mango arm of our study did not follow the same pattern, nutrient-extracted preparation of the mango juice did not adversely influence GI compared with whole fruit, with both preparations exhibiting a low GI

Summary

Introduction

Increased fruit consumption is associated with the lowering of risk from multiple chronic diseases;[1] and public health campaigns worldwide consistently aim to promote awareness of the positive health effects of fruit. Current UK public health guidance, including from Diabetes UK and the NHS, recommends limiting consumption of fruit juice to 150 ml per day. The rationale behind this advice is, in large part, based on a 470 000 female nurse cohort study from the United States[2] which when pooled with two other studies showed an association of fruit juice consumption with increased risk of type 2 diabetes (T2DM).[3] Consumption of whole fruit was not associated with T2DM risk but was associated with lowered risk. Two recent metaanalyses were not able to identify enough conclusive evidence to support an association between fruit juice consumption and T2DM.[5,6]

Methods

Results

Conclusion