Enzymatic treatment of apple juice can reduce its sugar content by 21 percent and postprandial glycaemia and venous serum insulin response by 68 percent and 47 percent, respectively, a study has shown. This further leads to a reduction of glycaemic load by 74.6 percent with no adverse gastrointestinal side effects.
This double-blind, randomized, placebo-controlled clinical trial with cross-over design included 30 male adults with impaired fasting glucose (IFG) who received 500 ml of either apple juice treated with invertase, glucose oxidase/catalase (verum; glucose 0.05 g; gluconate 18.2 g) or untreated apple juice (control; free glucose 8.5 g; bound glucose 6.7 g; gluconate below detection limit).
The authors twice measured postprandial fingerprick capillary blood glucose and venous serum insulin at baseline and at times 0 (start of drink), 15, 30, 45, 60, 90 and 120 min. They also evaluated gastrointestinal symptoms, stool consistency and satiety.
Verum led to a significantly lower incremental area under the curve (iAUC120) of glucose levels (primary parameter) compared to control (mean, 63.6±46.7 vs 198±80.9 min x mmol/l; ANOVA F, 137.4; p<0.001; α=0.05). The iAUC120 of venous serum insulin levels (secondary parameter) was likewise significantly lower after verum compared to control (mean, 2,045±991 vs 3,864±1,941 min x mmol/l; ANOVA F, 52.94; p<0.001; α=025).
Verum also improved other parameters of glucose metabolism and ISI=2/(AUC venous serum insulin x AUC glucose + 1) compared to control. Moreover, verum improved stool frequency and reduced stool consistency, as assessed by Bristol stool form scale.