A parallelized, randomized clinical study with 31 young healthy adults investigated the effects of a glucose solution (control group) or a glucose solution containing a guava fruit extract prepared by supercritical CO2 extraction (intervention group), during an oral glucose tolerance test (OGTT).

Blood samples were collected prior to and up to 2 hours after glucose consumption to quantitate blood glucose and insulin levels.

The results show that, in comparison to the control group, consumption of guava fruit extract resulted in a significantly reduced increase in postprandial glucose response over the basal fasting plasma glucose levels after 30 min (Δ control 2.60 ± 1.09 mmol/L versus Δ intervention 1.96 ± 0.96 mmol/L; p = 0.039) and 90 min (Δ contr. 0.44 ± 0.74 mmol/L versus Δ inter. -0.18 ± 0.88 mmol/L; p = 0.023). In addition, a slightly reduced, but non-significant insulin secretion (p = 0.302) was observed. Interestingly, storage time and repeated freeze-thawing operations appeared to negatively influence the efficacy of the applied extract.

Several substances at relevant concentrations including kojic acid (0.33 mg/mL) and 5-hydroxymethylfurfural (2.76 mg/mL) were identified as bioactive compounds.

This clinical trial confirms the efficacy of the guava fruit extract in inhibiting intestinal glucose resorption, possibly in combination with reduced insulin secretion. Based on these findings, this extract appears promising for patients with diabetes and for the prevention of insulin resistance.

König A, Schwarzinger B, Stadlbauer V, Lanzerstorfer P, Iken M, Schwarzinger C, Kolb P, Schwarzinger S, Mörwald K, Brunner S, Höglinger O, Weghuber D, Weghuber J. Guava (Psidium guajava) Fruit Extract Prepared by Supercritical CO(2) Extraction Inhibits Intestinal Glucose Resorption in a Double-Blind, Randomized Clinical Study. Nutrients. 2019 Jul 3;11(7).