Kombucha, a fermented beverage with a history spanning over 2,000 years, has recently surged in popularity, lauded for its potential health benefits, including weight loss. This article delves into the scientific evidence surrounding kombucha's impact on weight loss, inflammation, and gut health, considering various studies and perspectives.
What is Kombucha?
Kombucha is an ancient concoction made from tea (typically green or black), sugar (such as white, turbinado, agave, or honey), "healthy" bacteria, and yeast. The mixture ferments for one week to a month, resulting in a lightly carbonated drink with a distinctive vinegary taste. The fermentation process also introduces a small amount of alcohol, usually less than 0.5%, allowing it to be sold as a non-alcoholic beverage.
Potential Health Benefits of Kombucha
Kombucha's purported health benefits are often attributed to the probiotics it contains, similar to other fermented foods like sauerkraut, pickles, kimchi, kefir, and yogurt. While research on kombucha's specific effects is still evolving, compounds within kombucha have been linked to several potential advantages.
Weight Loss: A Closer Look
While kombucha alone is unlikely to cause significant weight loss without other dietary and lifestyle changes, it can be a valuable addition to a weight-loss plan. Replacing sugary sodas with kombucha can reduce calorie intake. However, it's crucial to choose kombucha varieties with lower sugar content, as some are heavily sweetened. The small amount of caffeine in kombucha may also contribute to a slight metabolic boost, potentially aiding in calorie burning.
Limiting Inflammation
Kombucha is rich in antioxidants and polyphenols, which protect the body from damage and help limit chronic inflammation. Polyphenols are known for their strong antioxidant properties and ability to decrease inflammation, a root cause of many diseases. The fermentation process can even increase the amount of polyphenols. However, kombucha should be part of a broader anti-inflammatory approach, such as combining it with a Mediterranean diet.
Read also: Drinking Kombucha on a Keto Diet
Boosting Gut Health
Kombucha contains probiotics that can help feed and increase beneficial gut bacteria, which can help decrease bad bacteria. Maintaining this balance can positively affect the digestive system and overall health.
Strengthening the Immune System
Kombucha boasts B vitamins, crucial for a healthy immune system. It also contains acetic, glucuronic, and D-Saccharic acids, which can be antimicrobial, fighting against harmful bacterial growth. Polyphenols further contribute to immune regulation.
Other Potential Benefits
Some research suggests that the antioxidants in kombucha may offer protection against cancer by reducing cell damage. Additionally, enzymes and acids in kombucha may assist the liver in detoxification, and some studies suggest it may help combat fatty liver disease. Kombucha may also improve cholesterol levels by increasing "good" HDL cholesterol and decreasing "bad" LDL cholesterol, potentially limiting plaque buildup in arteries.
Recent Study on Black Tea Kombucha and Gut Microbiota
A recent study published in The Journal of Nutrition investigated the effects of regular black tea kombucha consumption on gut health. The eight-week study involved participants with normal weight and obesity, with findings revealing that kombucha contains 145 phenolic compounds (flavonoids = 81%, phenolic acids = 19%) and promotes the growth of beneficial gut bacteria in both groups. The obesity group experienced the most benefit, with kombucha consumption leading to the growth of the butyrate producer Subdoligranulum and declines in obesity-associated genera like Ruminococcus and Dorea.
The study intervention involved the distribution of laboratory-prepared black tea kombucha (200 mL) for daily consumption. UPLC-MS-based characterization of the kombucha revealed it to be a rich source of phenolic compounds (n = 145), including flavonoids (81%) and phenolic acids (19%). Quercetin 3-O-rutinoside was found to be the most abundant phenol in the beverage.
Read also: Best Kombucha Brands
Key Findings:
- Beneficial Gut Microbial Effects: Regular kombucha consumption had beneficial effects on gut microbiota, particularly in individuals with obesity.
- Modulation of Gut Microbiota: Kombucha consumption modulated the gut microbiota in individuals with and without obesity.
- Increased Subdoligranulum: Obese participants experienced an increase in Subdoligranulum (a butyrate producer) populations.
- Reduced Ruminococcus and Dorea: Obese participants experienced significant reductions in Ruminococcus and Dorea (obesity-associated) genera.
- Rich in Phenolic Compounds: Kombucha was observed to be a rich source of beneficial phenols (n = 145), some of which have known anti-obesity benefits.
The study demonstrated that a small daily dose of kombucha made from black tea can meaningfully reshape the gut microbiome in adults, especially those with obesity, without dietary changes. The gut "makeover" boosts beneficial bacteria that play a big role in fighting inflammation and strengthening metabolic processes.
Following the eight-week intervention, scientists analyzed gut makeup and made some surprising discoveries. The microbial changes observed, particularly in the obese group, mimicked those seen in people with improved blood sugar control and lower inflammation.
The researchers discovered that, across the board, there were increased levels of Akkermansia muciniphila, a bacterium linked to lower inflammation, better insulin sensitivity and a more robust gut lining wall. The participants also saw a rise in bugs belonging to the Subdoligranulum genus. Bacteria in this group produce the beneficial short-chain fatty acid butyrate, which is linked to better blood sugar control and reduced liver fat. Similarly, a rise in Bacteroidota microbes, a group that helps break down carbohydrates and proteins, was also gauged. And, particularly in the obese cohort, Ruminococcus and Dorea numbers were down, which is a good thing - elevated levels of these have been consistently linked to visceral fat, inflammation, and metabolic disease.
The kombucha regimen also changed the makeup of fungal content in the gut, with Less Rhodotorula, Exophiala and Candida - all fungi associated with obesity, gut inflammation and consuming a Western diet.
While many probiotics focus on adding bacteria to the microbiome, kombucha appeared to create a more friendly environment for beneficial species already in the gut to flourish, especially those that thrive on antioxidant-rich polyphenols.
Read also: Does Kombucha Help You Lose Weight?
The microbial changes were more significant in the obese cohort - and, after the eighth week, these participants had gut profiles that resembled those of the "normal weight" group.
The researchers noted that a critical approach is needed when interpreting the role of certain microorganisms in health and disease, because there is no clear consensus in the literature. This requires considering not only the microorganisms themselves but also the complex intra- and interspecies relationships between bacteria and fungi, as indicated by some authors. Those studies have observed positive interactions between bacterial and fungal species, indicating a possible mutual dependence. Conversely, negative correlations suggest a competitive or inhibitory relationship, pointing to the potential for gut fungi to influence bacterial populations and vice versa. Additionally, the broader context of diet and other influencing factors must be considered when evaluating these findings.
Study on Green Tea Kombucha, Weight Loss, and Inflammation
Another randomized controlled clinical trial investigated the impact of green tea kombucha (GTK) on weight loss, inflammation, and salivary microbiota in individuals with excess body weight. The 10-week study involved two groups: a control group (CG) with caloric restriction and a kombucha group (KG) with caloric restriction plus 200 mL of GTK.
Methods:
- Participants with excess body weight were divided into two groups: energy-restricted diet (CG) and energy-restricted diet with green tea kombucha (KG).
- Body composition, anthropometry, saliva, and blood collection were performed at the beginning and end of the intervention.
- Plasma interleukins were determined by flow cytometry.
- Salivary microbiota was analyzed by 16S rRNA sequencing.
Results:
- Both groups decreased weight, BMI, and body fat (p < 0.001) after the intervention, but there were no differences between groups.
- The KG reduced lipid accumulation product (LAP) (p = 0.029).
- Both groups decreased IL-1β and IL-8, but IL-6 increased in the CG (p = 0.023) compared to the kombucha group.
- Alpha and beta diversity of salivary microbiota increased in the KG.
- The KG presented lower Bacillota/Bacteroidota ratio (p = 0.028), and BMI was positively associated with the Bacillota phylum.
Conclusions:
GTK did not enhance weight loss, but it decreased the LAP.
Study Design and Ethics
This was a parallel randomized controlled clinical trial with a duration of 10 consecutive weeks. Participants aged 18-45 years old were recruited through dissemination on social media and local newspapers in Viçosa, Brazil. Participants who expressed interest completed an online pre-screening questionnaire. They were required to have a Body Mass Index (BMI) of at least 27 kg/m², a high waist circumference (≥80 cm for women; ≥94 cm for men), and elevated body fat by Dual-energy X-ray Absorptiometry (DEXA) >30% for women and >25% for men). After screening, a one-week run-in period was applied to identify and exclude participants most likely to not adhere to the research protocol. Then, the selected participants were allocated to one of the two groups using the MinimPy software through the stratified minimization method based on BMI, age, and sex, to ensure the balanced distribution of potential factors that interfere with the outcome variables.
The project was approved by the Human Research Ethics Committee of the Federal University of Viçosa (UFV). All participants signed the Informed Consent Form (ICF) before the intervention and were enlightened about the benefits and risks inherent to the research, aware that they could withdraw at any time they wanted without any negative repercussions.
Kombucha Production and Composition
The green tea kombucha was produced in the Cereal Chemistry and Technology Laboratory in the Department of Food Technology-UFV, in accordance with the parameters established by the Ministry of Agriculture, Livestock, and Supply (MAPA). The individuals allocated to the KG were provided with seven bottles per week; they had to keep the bottles under refrigeration. Participants were instructed to consume one bottle per day, preferably at lunch or with food. The GTK final physicochemical composition is described in Table 1. In each bottle of kombucha (200 mL) consumed daily, there were 3.96 × 109 of lactic acid bacteria, 2.14 × 109 of acetic acid bacteria, and 3.14 × 109 of yeasts.
Dietary Intervention
Individuals of both groups received a food plan with a reduction of 500 kcal from their daily caloric requirement estimated using the Estimated Energy Requirement-EER. The food plan consisted of five different menus calculated based on the Brazilian Institute of Geography and Statistics (IBGE) 2008-2009 food tables. The distribution of macronutrients was based on the recommendations of guidelines for obesity management (55% carbohydrates, 30% lipids, 15% proteins). In addition, they received qualitative nutritional guidance regarding the healthy dish model, level of food processing, and orientations on how to better choose food with shopping tips. Moreover, they received a document with all the recipes prescribed in the food plans. They were encouraged not to change the foods or meals between the menus.
Measurements
The evaluation of anthropometric parameters was performed at the Laboratory of Energy Metabolism and Body Composition (LAMECC) during screening, in the 1st, 5th, and 10th week of treatment. Physical activity pattern was assessed at the beginning and end of the study using the International Physical Activity Questionnaire (IPAQ) validated for the Brazilian population. Food consumption was assessed by trained nutritionists through food frequency questionnaires (FFQs) that analyzed the individual’s usual food intake before the start of intervention and after it, considering the consumption during the last 10 weeks. Blood samples were collected at baseline and 10th week by a qualified nursing technician at the Clinical Analysis Laboratory of the Health Division-UFV (LACDSA).
Potential Risks of Kombucha
While generally safe, drinking too much kombucha could lead to reactions like headache, nausea, GI distress, or, in rare cases, ketoacidosis. Lead toxicity is possible if homemade kombuchas are fermented in clay vessels or containers that leach lead. Sanitation is also crucial when brewing homemade kombucha to avoid contamination. The Centers for Disease Control and Prevention advises that drinking approximately 4 ounces of kombucha per day "may not cause adverse effects in healthy persons." It's best to start slowly, especially if you're new to kombucha, and check the nutrition label for added sugar content.
Who Should Avoid Kombucha?
Pregnant women and individuals with compromised immune systems should generally avoid kombucha. It's also not typically recommended for young children.