Apple juice treated with invertase, glucose oxidase, catalase reduces glucose load

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.