Smaller declines in fasting blood sugar were also noted in the healthy subjects studied but these reductions did not reach statistical significance.
The US-based researchers emphasise: “To our knowledge, there are no studies showing that kombucha lactic acid bacteria, acetic acid bacteria, or yeasts could contribute to blood glucose lowering, suggesting that the observed effect may be mediated by bioactive end-products produced in situ by kombucha microbes.”
Microbiome and blood sugar
Diabetes mellitus is a widely prevalent condition and a leading cause death on a global scale, whilst being a major risk factor of many further conditions such as heart disease and stroke. Rates of diabetes have increased by over 400% in the past 30 years, which have been mostly attributed to T2D.
Following this, there has been a substantial interest in the search for natural dietary approaches to prevent the occurrence of this disease, with studies noting that fermented products containing microbes were associated with a reduced T2D risk.
Such bacteria-containing products have been found to significantly reduce increases in plasma glucose and insulin, whilst further research noted pancreatic beta cell regeneration.
Thus, the present pilot study sought to investigate the microbiome-modulatory effects of bacteria contained within a fermented kombucha product, and the potential anti-hyperglycaemic effect on those suffering with T2D.
The prospective, cross-over RCT included 12 middle-aged participants from a single-centre urban hospital system, two of which were diagnosed with type 2 diabetes.
The subjects were administered either a 240 ml kombucha product or a placebo control. The kombucha microbiota was determined using selective culturing and 16S rRNA gene (bacteria) and ITS (fungi) sequencing. End-products were also determined using HPLC.
Further secondary measures included various health parameters including gut and skin health, using administered questionnaires.
The bacterial strains identified within the kombucha were mainly comprised of lactic and acetic acid bacteria including Lactobacillus and Oenococcus, as well as yeasts such as Dekkera, with each group present at around 106 CFUs/ml.
It was found that consumption was associated with a significantly lowered average fasting blood glucose level after four weeks, in those with diabetes with elevated blood glucose levels (>130 mg/dL).
The study findings suggest that intakes of the kombucha drink may have led to a reduction in fasting blood sugar levels in those with type 2 diabetes.
Explaining the potential mechanisms of action, the report states: “First, as observed in animal models, kombucha was associated with improved pancreatic beta cell regeneration which could contribute to improved endogenous insulin production.”
“Second, chemical constituents formed by kombucha microbes may influence host metabolism and provide health benefits. These constituents include polyphenols, D-saccharic acid-1,4-lactone, caffeine, organic acids, ethanol, and various alkaloids,” the report adds.
The researchers emphasise that this area requires further larger scale RCTs to be conducted to confirm the conclusions hypothesised. Furthermore, the inclusion of the collection of faecal samples would enable for the assessment of the gut microbiota and the subsequent mechanisms of action behind the results.
Source: Frontiers in Nutrition
“Kombucha tea as an anti-hyperglycemic agent in humans with diabetes – a randomized controlled pilot investigation”
Chagai Mendelson, Sabrina Sparkes, Daniel J. Merenstein, Chloe Christensen, Varun Sharma, Sameer Desale, Jennifer M. Auchtung, Car Reen Kok, Heather E. Hallen-Adams, and Robert Hutkins