Effects of a hydroalcoholic extract of Juglans regia (walnut) leaves on blood glucose and major cardiovascular risk factors in type 2 diabetic patients: a double-blind, placebo-controlled clinical trial

Abstract

BackgroundWe aimed to evaluate the effects of a hydroalcoholic extract of Juglans regia L. leaves on blood glucose level and cardiovascular risk factors in type 2 diabetic patients.MethodsIn this randomized, double-blind, placebo-controlled, parallel-group (2 arms) clinical trial, 50 diabetic patients were divided into two groups: treatment group (receive the capsules containing 100 mg J. regia leaf extract) and control group (receive the capsules containing placebo, microcrystallin cellulose). Baseline participant data were matched between the two arms of the study. We administered the prepared capsules to the patients twice daily for 8 weeks. Blood glucose level, glycosylated hemoglobin (HbA1c) level, body weight, body mass index, blood pressure, lipid profile, serum insulin, and insulin resistance were compared between the two groups before and after the intervention. P < 0.05 was considered significant.ResultsAfter excluding eleven patients, 20 received J. regia leaf extract and 20 patients received placebo. The J. regia leaf extract did not significantly change the blood glucose and insulin resistance condition. However, in this group, body weight, body mass index, and systolic blood pressure significantly decreased compared with the baseline measurements (P = 0.028, P = 0.030, and P = 0.005, respectively). The lipid profile did not change significantly compared with the baseline measurements. In the control group, postprandial glucose and HbA1c levels significantly decreased after the intervention (P = 0.030 and P = 0.028, respectively). The other variables were not significantly different in this group. At the end of the study, the variables were not significantly different between the two groups.ConclusionIn this double-blind study, 200 mg/d of J. regia leaf extract had no significant effect on blood glucose level and HOMA-IR score in patients with type 2 diabetes. However, the J. regia leaf extract was effective in reducing body weight and blood pressure. An accidental finding of our study was that microcrystalline cellulose, a widely used placebo in clinical trials, led to a reduction in blood glucose level.Trial registrationIranian Registry of Clinical Trials (IRCT: 138901203180 N2, 2010/6/6); retrospectively registered.

A Comparative Review on the Extraction, Antioxidant Content and Antioxidant Potential of Different Parts of Walnut (Juglans regia L.) Fruit and Tree

“…The effect of 50% ethanolic extract prepared from walnut green husk and leaf on cutaneous Leishmaniasis caused by Leishmania major in BALB/c mice were also reported by Sharafi Chegeni, et al [162]. In a double-blind, placebo-controlled clinical trial study reported by Rabiei, et al [173], a hydroalcoholic extract (70%) of walnut leaves was used to evaluate its effects on blood glucose levels in type 2 diabetic patients and the major cardiovascular risk factors.…”

Cyclohexane extract of walnut leaves improves indices of oxidative stress, total homocysteine and lipids profiles in streptozotocin‐induced diabetic rats

“…Groups with the similar alphabet on each column are not significantly different, but different alphabets indicate a significant difference between groups, the label of "ac" means that it has no significant difference with columns labeled as "a" and "c (Delaviz et al, 2017). It can be said that anti-hyperglycemic and hypoglycemic effects of walnut leaf extract are probably due to flavonoids, such as quercetin and kaempferol (Rabiei et al, 2018). Vessal, Hemmati, and Vasei (2003) reported that 10 and 15 mg/kg doses of quercetin had no impact on plasma glucose level in normal animals, but significantly decreased the level of plasma glucose in streptozotocin-induced diabetic rats after 8-10 days, and blood glucose returned to the normal level (Vessal et al, 2003).…”

Plant Extracts for Type 2 Diabetes: From Traditional Medicine to Modern Drug Discovery

“…Two clinical studies have been conducted in Iran and Brazil, respectively, and the results demonstrated that two different leaf extracts were effective for resolving diabetic symptoms ( Table 8 ). Rabiei et al conducted a study to evaluate the effects of a hydroalcoholic extract of Juglans regia L. leaves on blood glucose level and cardiovascular risk factors in T2DM patients [ 122 ]. The trial was randomized, double-blind, placebo-controlled and parallel-grouped.…”