05 June 2024

Kombucha lowered glucose levels in people with type 2 diabetes

Tea mushroom (kombucha) lowered average fasting blood glucose levels in type 2 diabetic patients who drank it every day for four weeks. After one month, blood glucose was 2.67 millimoles per litre (p = 0.035) lower. However, there was no significant difference between glucose levels in the treatment and placebo groups. As reported in Frontiers in Nutrition, the tea mushroom microbiota consisted mainly of lactic acid and acetic acid bacteria and yeast.

The incidence of diabetes has increased by more than 400 per cent in the last 30 years, mainly due to type 2 diabetes. Therefore, the question of methods to lower blood glucose levels has become extremely relevant. This is particularly true for dietary approaches. For example, diets rich in fermented foods have been reported to reduce the risk of developing diabetes.

Tea mushroom (kombucha) is produced by fermentation of sweetened tea by a symbiotic consortium of bacteria and yeast (SCOBY). It has become particularly popular over the past decade, with a global market worth nearly $1.7 billion in 2019 and a projected annual growth rate of 20 per cent. The anti-hyperglycaemic effects of tea mushroom were found in diabetic rats with histological evidence of pancreatic beta-cell regeneration.

Robert Hutkins from the University of Nebraska-Lincoln and colleagues studied the effect of consuming 240 millilitres of tea mushroom at dinner daily for four weeks on blood glucose levels. A total of twelve volunteers with type 2 diabetes (of whom nine were women) were included in the study, of whom only seven completed the entire study. The average age of the twelve participants was 57 years, with half of all participants being over 50. Nine participants were receiving insulin therapy.

Tea mushroom significantly reduced mean fasting blood glucose levels at week four compared to baseline (9.11 millimoles per litre versus 6.44, p = 0.035); no such effects were observed in the placebo group. However, despite the significant difference in the tea mushroom group, the difference between fasting blood glucose levels after four weeks between the treatment and placebo groups was not statistically significant (p = 0.265).

Microbiological analysis of the tea mushroom showed that it was mainly dominated by lactic acid (1.1 × 106 colony-forming units per milliliter) and acetic acid bacteria (9.5 × 105 colony-forming units per milliliter) and yeast (7.5 × 105 colony-forming units per milliliter). The number of mould fungi was approximately 2.0 × 102 per millilitre.

Using 16S rRNA gene sequencing, the scientists determined that the tea fungus community consisted mainly (> 80 per cent) of members of the Bacillota (formerly Firmicutes) type, with several genera of the family Lactobacillaceae predominating. The other major type, with an abundance of 12 per cent, was Pseudomonadota (formerly Proteobacteria), which consisted of several genera of acetic acid bacteria including Komagataeibacter, Gluconobacter and Acetobacter. Yeasts and fungi were dominated mainly by Dekkera and Sordariales. Species included Calycina discreta (formerly Pezizella discreta), Candida ethanolica, Brettanomyces anomalus and a few others.

Thus, this pilot study shows that regular consumption of tea mushroom has a positive effect on blood glucose levels in patients with type 2 diabetes. However, larger studies are required to confirm the effect.

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