Impact of Poplar Propolis on Metabolic Disturbances of Insulin Resistance

Impact of Poplar Propolis on Insulin Homeostasis and Pancreatic Cell Function in Insulin Resistant Subjects

Propolis, a natural resinous mixture rich in polyphenols, produced by bees from a variety of plant sources, has shown significant therapeutic effects and may prevent the development of certain chronic diseases. Current evidence supports the beneficial effect of these bioactive phytochemicals on the management of type 2 diabetes mellitus (T2DM) and other chronic diseases. The objective of this study is to evaluate the effect of poplar propolis extract powder (PPEP) on glucose homeostasis and other clinical parameters in insulin-resistant patients (diagnosed by HOMA-IR index > 1.85 for men and > 2.07 for women).

Backgroud: Propolis, a natural resinous mixture rich in polyphenols, produced by bees from a variety of plant sources, has shown significant therapeutic effects and may prevent the development of certain chronic diseases. Current evidence supports the beneficial effect of these bioactive phytochemicals on the management of type 2 diabetes mellitus (T2DM) and other chronic diseases. The objective of this study is to evaluate the effect of poplar propolis extract powder (PPEP) on glucose homeostasis and other clinical parameters in insulin-resistant patients (diagnosed by HOMA-IR index > 1.85 for men and > 2.07 for women). Methods: The trial was a randomized, controlled, crossover, intervention study. Insulin-resistant patients (n=9) (8 women, 1 man), with a mean ± SD age 49 ± 7, were subjected to two periods of supplementation (propolis and placebo) for 3-months, separated by a 2-week washout period. The quantity of propolis administered was determined individually to reach 6 mg of polyphenols/kg. Fasting blood test and oral glucose tolerance test (OGTT) were performed before and after each treatment.

The present trial was a randomized, double-bind, controlled, crossover, dietary intervention study. During this trial, two types of supplementations were randomly administered during two treatment periods (propolis and placebo), using a random number table. The placebo served as the reference group for comparison. Participants and caregivers were blinded to the type of treatment consumed.

Propolis supplements were packaged in marine capsules and consisted of poplar propolis powder (propolis concentrate, carob powder, magnesium stearate and silicon dioxide), concentrated to 30% total polyphenols. Each supplementation period lasted 3 months, with a 2-week wash-out period, to allow total excretion of polyphenols by the body and do not interfere with the new supplementation phase. The subjects in this study were submitted to five visits, allowing the tracking of biological parameters (clinical examination, fasting blood samples, HGPO) during the study. During the supplementation phases, follow-up by telephone call was performed.

Placebo powder capsules (maltodextrin, fatty acids, magnesium salts and silicon dioxide) are presented in the same packaging to have an identical appearance and taste. Patients in the propolis group were dosed with propolis to reach 6 mg total polyphenols/kg body weight, based on the results of a previous preclinical study in mice. Each supplementation period lasted 3 months, with a 2-week wash-out period, to allow total excretion of polyphenols by the body and do not interfere with the new supplementation phase. The subjects in this study were submitted to five visits, allowing the tracking of biological parameters (clinical examination, fasting blood samples, HGPO) during the study. During the supplementation phases, follow-up by telephone call was performed.

Propolis supplements were packaged in marine capsules and consisted of poplar propolis powder (propolis concentrate, carob powder, magnesium stearate and silicon dioxide), concentrated to 30% total polyphenols. Each supplementation period lasted 3 months, with a 2-week wash-out period, to allow total excretion of polyphenols by the body and do not interfere with the new supplementation phase. The subjects in this study were submitted to five visits, allowing the tracking of biological parameters (clinical examination, fasting blood samples, HGPO) during the study. During the supplementation phases, follow-up by telephone call was performed.

Placebo powder capsules (maltodextrin, fatty acids, magnesium salts and silicon dioxide) are presented in the same packaging to have an identical appearance and taste. Patients in the propolis group were dosed with propolis to reach 6 mg total polyphenols/kg body weight, based on the results of a previous preclinical study in mice. Each supplementation period lasted 3 months, with a 2-week wash-out period, to allow total excretion of polyphenols by the body and do not interfere with the new supplementation phase. The subjects in this study were submitted to five visits, allowing the tracking of biological parameters (clinical examination, fasting blood samples, HGPO) during the study. During the supplementation phases, follow-up by telephone call was performed.

The primary outcome was change in the Matsuda-DeFronzo Insulin Sensitivity Index (ISI-M) at the end of supplementation. The ISI-M is calculated by the following formula: 10,000 / square root [(Glu0 × Ins0) × (Glumean OGTT × Insmean OGTT)], where Glux and Insx represent plasma glucose (mg/dL) and insulin values (UI/L), respectively, at time x min during. The ISI-M index, proposed by Matsuda and Defronzo, makes it possible to estimate insulin sensitivity derived from the OGTT

Glycaemia at T0, T30, T60, T90 and T120 (mmol/L) mesured after after an oral glucose tolerance test (OGTT).

Insulinemia at T0, T30, T60, T90 and T120 (mUI/L) mesured after after an oral glucose tolerance test (OGTT).

Enzymatic determination of alanine aminotransferase (ALAT) and aspartate aminotransférase (ASAT) (UI/L).

Estimation of creatinine clearance (mL/min) by formula : 1,23 (for men) or 1,04 (for women) x weight (kg) x (140 - age)/creatinine (mg/L).

Inclusion Criteria: Body mass index (BMI) ≥ 30 kg/m2 Insulin resistance defined as a HOMA-IR index > 1.85 for men and > 2.07 for women Exclusion Criteria: Presence of diabetes Recent weight change (≥ 5% in the last 3 months) Documented allergy to bee products and/or fish products Positive serology for human immunodeficiency virus or hepatitis High blood pressure Elevated transaminases (AST > 40 IU/L ; ALT > 45 IU/L) Low creatine clearance (estimated glomerular filtration rate < 90 ml/min) Interfering treatment (cholesterol-lowering treatment, intestinal absorption modulating treatment, absorption modulating treatment and/or insulin sensitivity) Gastrointestinal tract surgery Pregnancy and / or lactation.