The new randomised, double-blind, placebo-controlled trial assessed the effect of 800 mg/d green coffee extract (GCE) or placebo in 44 patients with type 2 diabetes (T2D) and overweight/obesity over 10 weeks.
The authors from Iran conclude: “Findings showed beneficial effects of green coffee extract (GCE) on systolic blood pressure (SBP), triglyceride (TG), high-sensitivity C-reactive protein (hs-CRP), and high-density lipoprotein (HDL) levels in patients with T2D and overweight/obesity over a 10-week period of supplementation."
Global prevalence of diabetes is expected to reach 629 million by 2040.
Patients with T2D face an elevated risk of cardiovascular and renal diseases due to comorbidities such as fatty liver disease, atherogenic dyslipidemia, and hypertension, and managing T2D requires pharmacotherapy, lifestyle changes, and dietary modifications.
Previous studies have also focused on the effects of nutraceuticals on treating or preventing diabetes complications.
For instance, green coffee bean, the unroasted coffee fruit, is rich in bioactive phytochemical compounds, offering potential in T2D management.
The main bioactive ingredient of green coffee is chlorogenic acid (CGA), which has shown beneficial effects on blood pressure, inflammatory markers, oxidative stress, and diabetes in experiments.
The proposed mechanisms by which CGA exerts its effects include inhibiting the cytochrome P450 1A enzymes that increase the pro-inflammatory response, increasing the expression of genes that reduce oxidative stress, decreasing insulin resistance by activating the hepatic proliferation-activated receptor α (PPAR-α), or improving blood glucose by activating AMP-activated protein kinase (AMPK).
However, according to the authors, the health benefits of green coffee for humans are inconsistent, and while GCE has shown protective effects against chronic diseases, research on its impact on T2D is limited.
“Existing studies often focus on CGA rather than GCE, and results are inconsistent,” the authors of the new study note.
“Consequently, a clinical trial has been designed to evaluate the effects of GCE supplementation on glycemic indices, lipid profile, hs-CRP, and malondialdehyde in patients with T2D and overweight/obesity.”
This trial recruited individuals with T2D and overweight/obesity who were referred to the Taleghani Hospital, Tehran, between June 2022 and December 2022.
Participants (26 male and 18 female) were randomly assigned into two groups of 22, receiving either oral capsules of GCE or a homologated placebo (starch), both produced by Bonyan Salamat Kasra Co., Tehran, Iran.
Glycemic indices, lipid profiles, anthropometric examinations, blood pressure, high-sensitivity C-reactive protein (hs-CRP), and malondialdehyde (MDA) were measured twice, at baseline and at the end of the study.
Results found that after 10 weeks of supplementation, GCE supplementation significantly reduced body weight (p = 0.04) and body mass index (BMI) (p = 0.03) compared to the placebo.
Analysis showed patients in the GCE group had a lower fasting blood glucose (FBG) concentration compared to the placebo group; however the authors note that this decreasing was marginally significant (8.48 ± 8.41 vs. 1.70 ± 5.82 mg/dL, p = 0.05).
Significant changes in SBP (p = 0.01), TG level (p = 0.02), HDL (p = 0.001), and TG-to-HDL ratio (p = 0.001) were also found between the intervention and placebo groups.
Additionally, hs-CRP levels significantly decreased in the GCE group compared to the placebo group (p = 0.02).
The trial indicated GCE supplementation had no effect on diastolic blood pressure (DBP), low-density lipoprotein (LDL), or total cholesterol.
No significant changes were observed in the MDA level between the two groups at the end of the study (p = 0.54), and there was no significant difference in insulin levels and homoeostasis model assessment of insulin resistance (HOMA-IR) between the groups.
The authors conclude: “Based on the findings of our study, GCE administration at a dosage of 800 mg/d for 10 weeks in patients with T2D decreased SBP, TG, and CRP and increased HDL compared to placebo. Moreover, FBG reduction in GCE group was marginally significant compared to the placebo group.”
They do however note: “Using a fixed dose of GCE and a short period of intervention were the limitations of the current study.
“Therefore, additional studies with a large sample size, different dosages, and longer durations are required to demonstrate the potential effects of GCE in patients with T2D."
Journal: Frontiers in Nutrition
Effects of green coffee aqueous extract supplementation on glycemic indices, lipid profile, CRP, and malondialdehyde in patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial
Authors: Sajad Khalili-Moghadam, Mehdi Hedayati, Mahdieh Golzarand, and Parvin Mirmiran.