Bitter gourd reduces elevated fasting plasma glucose levels in an intervention study among prediabetics in Tanzania.

ETHNOPHARMACOLOGICAL RELEVANCE: Impaired glucose tolerance and diabetes mellitus have become major health issues even in non-industrialized countries. As access to clinical management is often poor, dietary interventions and alternative medicines are required. For bitter gourd, Momordica charantia L., antidiabetic properties have been claimed. AIM OF THE STUDY: The main objective of the intervention study was to assess antidiabetic effects of daily bitter gourd consumption of 2.5g powder over the course of eight weeks among prediabetic individuals. MATERIALS AND METHODS: In a randomized placebo-controlled single blinded clinical trial, 52 individuals with prediabetes were studied after consuming a bitter gourd or a cucumber juice. For reducing the impact of between subject differences in the study population, a crossover design was chosen with eight weeks for each study period and four weeks washout in between. Fasting plasma glucose was chosen as the primary outcome variable. RESULTS: Comparing the different exposures, the CROS analysis (t=-2.23, p=0.031, r=0.326) revealed a significant difference in the change of FPG of 0.31mmol/L (5.6mg/dL) with a trend (R2=0,42387). The number of 44 finally complete data sets achieved a power of 0.82, with a medium-to-large effect size (Cohen's d 0.62). The effect was also proven by a general linear mixed model (estimate 0.31; SE: 0.12; p: 0.01; 95%CI: 0.08; 0.54). Not all participants responded, but the higher the initial blood glucose levels were, the more pronounced the effect was. No serious adverse effects were observed. CONCLUSIONS: Bitter gourd supplementation appeared to have benefits in lowering elevated fasting plasma glucose in prediabetes. The findings should be replicated in other intervention studies to further investigate glucose lowering effects and the opportunity to use bitter gourd for dietary self-management, especially in places where access to professional medical care is not easily assured.

Momordica charantia and type 2 diabetes: from in vitro to human studies.

Type 2 diabetes is a growing health problem worldwide that is particularly severe in India and China. In these areas, bitter gourd (Momordica charantia) is a popular vegetable which is traditionally known to have health beneficial effects not only, but mainly, on diabetes. Bitter gourd could be a cheap possibility to help the poor in these and other countries to control their blood glucose levels. This review describes anti-diabetic effects of bitter gourd reported in the literature and discusses what still needs to be clarified for developing an evidence-based and safe use of the bitter gourd for diabetes. Analyses of bioactive compounds have shown that bitter gourd is rich in nutrients and phytochemicals of which some have anti-diabetic effects. Juices, powders, extracts, and isolated compounds have been tested in vitro and in vivo. Bitter gourd increases insulin secretion of the pancreas, decreases intestinal glucose uptake, and increases uptake and utilization of glucose in peripheral tissues. Although human studies with type 2 diabetics are weak in their design and/or results, some of the studies do indicate anti-diabetic effects in patients and safety for bitter gourd treatment in humans. In the future, well designed studies with rodents will help to understand what kind of bitter gourd variety, dosage, preparation, and duration of administration is optimal. Such results will help to design human studies which are necessary to prove the effectiveness of bitter gourd in patients.