Plain language summary
Dried fruits show promising potential for blood glucose management. However, the effect of combining dried fruits with high glycaemic index (GI) foods has not been adequately addressed. The main objectives of this study were to: a) quantify the GI of 4 different types of dried fruit (dates, apricots, raisins, sultanas); and b) assess the ability of these 4 dried fruits to decrease the postprandial glycaemic response to white bread by partially displacing available carbohydrate and by providing a ‘catalytic’ dose of fructose. This study is a randomised multiple - crossover acute feeding trial which enrolled 10 participants of which 7 were males. Each participant underwent a total of 15 separate study meals consisting of 3 white bread control meals and 12 dried fruit test meals. Results demonstrate that dried fruit have a lower GI than white bread and can lower the glycaemic response of white bread through displacement of half of the available carbohydrate. None of the dried fruits showed a beneficial ‘catalytic’ fructose effect. Authors conclude that their findings may help to stimulate important industry innovation and improve the design of future clinical investigations that will potentially lead to the use of dried fruits as an effective tool to modify the glycaemic response of high carbohydrate foods.
Abstract
BACKGROUND/OBJECTIVES To investigate the effect of dried fruit in modifying postprandial glycemia, we assessed the ability of 4 dried fruits (dates, apricots, raisins, sultanas) to decrease postprandial glycemia through three mechanisms: a glycemic index (GI) effect, displacement effect, or 'catalytic' fructose effect. SUBJECTS/METHODS We conducted an acute randomized, multiple-crossover trial in an outpatient setting in 10 healthy adults. Participants received 3 white bread control meals and 12 dried fruit test meals in random order. The test meals included each of 4 dried fruits (dates, apricots, raisins, sultanas) alone (GI effect), 4 of the dried fruits displacing half the available carbohydrate in white bread (displacement effect), or 4 of the dried fruits providing a small 'catalytic' dose (7.5 g) of fructose added to white bread ('catalytic' fructose effect). The protocol followed the ISO method for the determination of GI (ISO 26642:2010). The primary outcome was mean ± SEM GI (glucose scale) for ease of comparison across the three mechanisms. RESULTS Ten healthy participants (7 men, 3 women; mean ± SD age and BMI: 39 ± 12 years and 25 ± 2 kg/m2) were recruited and completed the trial. All dried fruit had a GI below that of white bread (GI = 71); however, only dried apricots (GI = 42 ± 5), raisins (GI = 55 ± 5), and sultanas (51 ± 4) showed a significant GI effect (P < 0.05). When displacing half the available carbohydrate in white bread, all dried fruit lowered the GI; however, only dried apricots (GI = 57 ± 5) showed a significant displacement effect (P = 0.025). None of the dried fruits showed a beneficial 'catalytic' fructose effect. CONCLUSIONS In conclusion, dried fruits have a lower GI and reduce the glycemic response of white bread through displacement of half of the available carbohydrate. Longer-term randomized trials are needed to confirm whether dried fruit can contribute to sustainable improvements in glycemic control. TRIAL REGISTRATION ClinicalTrials.gov identifier, NCT02960373.
Methodological quality
Jadad score
:
3
Allocation concealment
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Yes
