Review on the current evidence on physiological activity and health effects of kombucha
Kombucha beverage is fermented probiotic drink made from tea, which has been used as a traditional remedy to boost detoxification and overall health in the Far East for centuries. It is produced in a process of fermentation of sweetened green or black tea that is added to Kombucha scoby (a symbiotic culture of bacteria and yeast) which creates a very distinctive beverage with sweet, sour and tart flavor, rich in probiotic cultures and various other nutrients. The Kombucha drink is used as base for production of Kombucha extract in a specific technologic process of short, low temperature pasteurization and concentration. The Kombucha beverage has a distinctive nutritional content of minerals, vitamins, certain enzymes, organic acids and probiotic bacteria and fungy. The Kombucha extract contains traces amount of specific minerals (Mg, Ca, K, Zn, Fe, Cu, Mn, Ni and Co) and vitamins (B1, B2, B3, B5, B6 and C) and a unique combination of organic acids such as acetic, lactic, gluconic and predominately glucuronic acid that provide wide range of beneficial metabolic effects in the body. Although the process of production of the extract destroys all probiotic cultures, the end product in form of Kombucha extract reaches over 100 times greater concentration of the specific acids and other beneficial compounds compared with their presence in the Kombucha beverage (1 Tbs of around 10ml of Kombucha extract has nutritional potency that equals around 600 ml of the fermented Kombucha beverage). The research and analyses conducted by the USFDA,other authorized national food agencies, health institutes and scientists and medical researchers worldwide have confirmed the safety for using Kombucha and its products as novel and functional food/ food supplement and large number of beneficial health properties that are clearly presented in the text bellow.
Current view on Kombucha health benefits
During the last 15 years there has been a constant rise of the interest for Kombucha and its products which correlate to an increasing number of studies and research that continue to prove the various health benefits of Kombucha. In general, the beneﬁcial properties of Kombucha have been attributed primarily to the specific acidic composition (high concentration of glucuronic acid (GlcUA), lactic, usnic acid, etc.) and their participation and impact on various metabolic processes in the body.
The present day lifestyle with continual stress and lack of time has put negative impact on the quality of nutrition and eating habits. The overly processed and refined food rich in additives and preservatives, the intake of fast foods filled with oxidized fats and excess of sugar, agricultural produce contaminated with pesticides, heavy metals and other industrial chemicals, alcohol consumption and overuse of medication overburdens the organism with toxins that continually damage our cells and block various metabolic functions, while restricting the body from obtaining all nutrients necessary to maintain a healthy metabolism. Optimal regulation of the liver detoxification pathways is an essential element of the human metabolism, critical to maintaining good health and wellbeing. In addition to ensuring normal liver function the detoxification capacity of the body directly impacts immune function, weight loss, lipid and sugar metabolism as well as the work of the endocrine (hormonal) system. Impaired detoxification pathways and weakened liver function affect all organ systems and lead to development of various chronic diseases. It is recognized that insufﬁcient and imbalanced nutrition can have a detrimental effect on detoxification ability. All biochemical reactions within phase 1 and 2 of the liver detoxification pathways depend on availability and adequate levels of specific nutrients such as proteins, vitamins, essential minerals, antioxidants, enzymes and other organic compounds. Further to this, it is certain that many detoxification processes, such as glucuronidation (key phase 2 biochemical reaction), are reduced in elderly people. These deﬁciencies can decrease the body’s ability to synthesize the bio transforming enzymes essential for proper detoxification. All these elements impair proper liver function and consequently lead to development of fatty liver disease (liver steatosis). Fatty liver disease is one of the most frequent and sadly most underappreciated diseases today. The latest data from the World’s Health Organization for gastroenterology show that 1/5 of the world’s population on average suffers from liver steatosis, or non-alcoholic fatty liver disease. If the condition of liver steatosis is not treated for a longer period of time it can lead to destruction of the hepatocytes, their replacement with fibrosis-connective tissue and development of liver cirrhosis, a life threatening condition with detrimental effect.
The Kombucha extract is one of the best and most concentrated, natural sources of glucuronic acid. This acid plays a key role in the phase 2 of the liver detoxification metabolic reactions, such as the process of glucuronidation . It conjugates - it binds to toxic metabolites and exogenous chemicals called xenobiotics (such as pharmaceuticals, environmental pollutants, toxins such as pesticides) present in the human body and modiﬁes them into compounds that have better solubility, which ensures flushing out of these toxic compounds from the liver, with gallbladder secretion, through the intestines out of the body. Emphasis should be put on the notion that the process of glucuronidation accounts for up to 60% of the metabolization of the analgesic and antipyretic medications. In that regard, it can be stated that by supporting the process of glucuronidation, the intake of kombucha has been shown to prevent hepatotoxicity caused by overuse of paracetamol or acetaminophen, (chemically named N-acetyl-p-aminophen) which was measured by reduced plasma levels of specific liver enzymes (glutamic oxaloacetate transferase, serum glutamic pyruvate transferase, LDHE, and MDA). Kombucha has also demonstrated hepatoprotective and curative properties against toxicity induced by carbon tetrachloride (CCl4 xenobiotic) and aflatoxin (mold toxin). In conclusion, the Kombucha intake in the presented experimental studies has resulted in reduced number of fatty droplets in the hepatocytes, which signifies inhibition of the accumulation of triglycerides and total cholesterol within the hepatocytes, as well as greatly increased productivity of the hepatic cells, due to the presence of glucuronic acid as a detoxiﬁer, as well as the presence of polyphenolics. (9, 10, 11, 12, 13, 14, 18, 28, 30, 52)
Oxidative stress - cumulative damage free radicals cause to the cells (cell’s membrane, mitochondria and other organelles, as well as the nucleus (the molecule of DNA)) results in reduced nutrient transport, weakened energy and molecule production and altered replication of the cell, which leads to impaired cellular function and metabolism. Without proper antioxidant defense, which serves the purpose of effective neutralization of the scavenging free radicals, the continual oxidative damage creates inflammations on a cellular level that creates systemic inflammation, tissue and organ damage and development of an illness. The phenolic and other compounds in the Kombucha (that originate from the tea) have potent antioxidant abilities to prevent free radical molecules and tissue damage, in particular to prevent lipid peroxidation (in the blood plasma and the vascular epithelial lining) which leads to creation of arterial plaque and development of atherosclerosis (frequent cardiovascular disease that can result in formation of arterial blockages, hearth failures and brain strokes). Medical studies conducted on patients with atherosclerosis, patients with high plasma cholesterol, reported significant reduction of atherosclerosis symptoms. Specifically, in addition to preventing lipid peroxidation, Kombucha could lower cholesterol level in the body through the inhibition of cholesterol synthesis enzyme HMG (3hydroxy 3-metilglutaril CoA reductase) activity in liver and/ or through the mechanism of increased excretion of cholesterol. The glucuronic acid found in Kombucha can neutralize cholesterol deposits supporting liver and kidneys in excreting the excess sterols (types of lipid molecules cholesterol belongs to) from the body. The results that were obtained in the studies demonstrated the ability of the Kombucha to decrease blood plasma total cholesterol by up to 52%, also reducing triglyceride values up to 27%, LDL-Ch up to 91%, while increasing HDL-Ch levels up to 27%. (9,12, 13, 20, 18, 24, 26, 36)
It has also been reported that Kombucha potentiates the hepatic glutathione antioxidant/detoxification system. Glutathione is the master endogenous antioxidant which together with its antioxidant enzymes (glutathione peroxidase, glutathione transferase and glutathione reductase) have essential role in the body’s detoxification capacity. By preventing oxidative damage the consumption of Kombucha prevents development of a wide number of systemic inflammation and chronic conditions such as cardiovascular diseases, kidney insufficiencies, eye diseases, degenerative cognitive diseases of the nervous system, etc. Secondary to this, Kombucha’s antioxidant properties and the ability to prevent oxidative stress, also give support to the immune system and better controlled inflammatory response. (16, 17 - 19)
Regular consumption of Kombucha also provides protection against anemia and has an energizing effect. Kombucha intake increases the energy level by improving significant aspects of the energy metabolism. Iron is the essential part for the formation of hemoglobin, which is an oxygen carrying protein present in the red blood cells. The increased hemoglobin levels directly increases the oxygen carrying capacity of the red blood cells, which improves the tissues’ supply with oxygen, which in turn allows for greater energy production inside the cells (by stimulatating ATP synthesis in the mitochondria). More specifically the Kombucha’s ability to prevent anemia and increase the levels of energy come from the formation of the iron and gluconic acid synthesized chelating complex (ability to chelate-bind to metals). The organic acids in the Kombucha, can improve the plant-derived (non-heme)) iron absorption, by reducing trivalent iron compounds from plant sources to divalent iron ions, and forming chelate compounds with them that dissolve well in an acidic medium. Also present B vitamins support the energy regeneration by enzymatic activation of lipid and protein metabolism. Consumption of Kombucha is particularly recommended for elderly people and vegetarians because it enhances the absorption of plant source iron and helps prevent iron deﬁciency and anemia caused by it. (9,10,12,13,17 - 20, 23 - 41)
Regular intake of Kombucha in form of fermented tea or as extract has also shown the ability to provide beneficial effect to the health and function of the gastrointestinal system. The overuse of nonsteroidal anti-inﬂammatory pharmaceuticals has gastro toxic effect that often leads to gastric ulceration and delayed healing. The research conducted until now shows several mechanisms of action that make Kombuca intake beneficial. It prevents oxidative stress, particularly peroxidation of lipids in the epithelial cells of the stomach, which in addition to acid secretion, also contributes to stomach ulceration. It also better regulates gastric and intestinal function (such as contraction of the stomach and intestines). Further to this, the healing ability of the Kombucha extract is mainly attributed to its capability to protect the mucin content (the ﬁrst guarding line-mucin and bicarbonates barrier). Study has confirmed that Kombucha extract preparation (15mg/kg) is as effective in ulcer healing as the positive control omeprazole (3mg/kg). (23)
Diabetes mellitus is one of most prevalent chronic metabolic diseases in the world. Either as dysfunction of endogenous insulin secretion (type 1) or as a result of different metabolic misbalances (such as insulin resistance in type 2) the condition of diabetes melitus affects nearly half a billion people worldwide and is one of the leading causes for development of cardiovascular diseases, eye diseases, kidney insufficiencies, limb amputations and other serious complications. The antidiabetic property of the Kombucha was first mentioned as early as 1929. Several studies conducted on animals demonstrate strong ability of the Kombucha to lower blood sugar levels and to keep low, stabile blood sugar levels. Kombucha has the ability to inhibit the digestion of starches (starch hydrolysis) by influencing the activity of the enzyme pancreatic amylase as well as to decrease the action of the pancreatic lipase, which in turn decreases the digestion and uptake of lipids, decreasing the level of blood glucose. In addition the consumption of Kombucha provides protection of the liver-kidney functions, evidenced by signiﬁcant decreases in key enzymes such as aspartate transaminase (ASAT), alanine transaminase (ALAT), and other as well as the urea contents (all of which are normally increased by hyperglycemia). By regulating the digestion and uptake of starches (carbohydrates) and lipids Kombucha demonstrates an antiobesity effects and it has been mentioned that regular Kombucha ingestion contributes to better weight control and inhibition of weight gain. (13, 24, 25, 26)
Beside liver, kidneys have an important role in blood filtration and elimination of toxins, which makes them particularly prone to oxidative stress and damages induced by toxins and increased metabolic waste product present in the blood. The Kombucha’s intake contribution to eliminate the damage caused by environmental pollutants is already reported in studies and could be of significance to patients suffering from renal impairment or patients with kidney stones. The unique blend of acids, particularly present in the Kombucha extract, such as glucuronic acid and other, increases water-solubility and improves transport and bioavailability of steroid hormones and fat-soluble vitamins, prevents an accumulation of heavy metals, insoluble` oxalates, inorganic salts of calcium, phosphorus, and uric acid. The regular intake of Kombucha has the potential to reduce kidney calciﬁcation and has been proven repeatedly to prevent kidney stone formation prevention. (11, 13, 20, 44)
Increased oxidative stress and unbalanced blood sugar levels are also associated with induction of neurodegenerative diseases. The unique nutritional profile of the Kombucha, presented by the specific combination of acids, amino acids, vitamins and other bioactive molecules provide nutrients required for normal function of the nervous system. The consumption of Kombucha may help in prevention of headaches, nervousness, depression in elderly and epilepsy. (9, 13 20, 24, 54, 55)
The glucuronic acid found in abundance in Kombucha can be used and converted by the body to glucosamine, chondroitin-sulphate, other acidic mucopolysaccharides and glucoproteins present in the cartilage, collagen and the ﬂuid that lubricates joints. This demonstrates the ability to use Kombucha as resource to obtain many key elements necessary for the cartilage and joint’s overall health and function. The possibility of Kombucha’s consumption to relieve arthritis and be used as dietary supplement for osteoarthritis has been successfully demonstrated in clinical tests in the USA, Russia, Sweden, and Germany. Further to this, Kombucha’s detoxifying abilities (mainly established by the support for the process of glucuronidation has been proven remedial against rheumatism and gout, in addition to arthritis (all 3 conditions characterized by accumulation of toxins in the joints). (20,58, 59, 60)
It has been reported that incidence of cancer in population that regularly consumes Kombucha tea or Kombucha extract is extremely rare. Several researches demonstrate Kombucha’s ability to inhibit cancer formation and growth by several mechanisms. Initially, by neutralizing free radical damage it preserves healthy cell metabolism, preventing abnormal cellular cycles and potential development of malignant cells. Furthermore, long-term Kombucha consumption increases immune system’s anticancer defensive properties by preventing cancer cell’s proliferation in particular, at early stages of tumor growth, due to synergetic action of the glucuronic, lactic and acetic acid, and antibiotic compounds found in Kombucha. In recent studies, it was also shown that Kombucha significantly reduced cancer cell’s development and metastasis, by inhibiting growth of blood vesicles in the cancer tissue (downregulation of angiogenesis) especially in hormone-dependent tumors. (13, 18, 20, 22, 34, 62)
Last but not list, Kombucha has demonstrated antimicrobial and antibiotic activities that can offer alternative to current synthetic antimicrobial pharmaceuticals (considering the increasingly important challenge of resistance to antibiotics). Precisely, many studies proved that Kombucha with high total acidity, as a result of high concentration of glucuronic, gluconic, lactic and other acids, exert antibacterial activity against a broad range of pathogenic bacteria, in particular, against Helicobacter pylori, Salmonella typhimurium, Staphylococcus aureus, Bacillus cereus, etc. This antimicrobial activity of Kombucha is contributed to the acids and low pH of the Kombucha which inhibits bacterial growth, by disrupting the bacterial wall membrane, inhibiting essential metabolic reactions and accumulation of toxins inside the cell of the bacteria. (2,8,17,19, 36–41, 60-75)
Regular consumption of kombucha, in particularly kombucha extract has demonstrated beneficial health properties in broad range of metabolic conditions and disorders. These properties to support specific organ functions and metabolic pathways and to prevent development of diseases are atrubuted to the unique nutritional and chemical composition, predominately represented by the specific profile of acids (glucuronic, gluconic, lactic and other) and other bioactive molecules present in the Kombucha.
Large number of studies and research, bot conducted on animals and humans have confirmed Kombucha’s properties to:
- - provides efficient detoxification of the liver and cleaning up of the blood of all toxins, by supporting key segments of the liver detoxification pathways;
- - prevent liver diseases by metabolizing pharmaceuticals known to cause liver toxicity and enhancing the activity of liver hepatocytes;
- - regulate blood lipids (by downregulating i.e. reducing the levels of blood triglycerides, total cholesterol and oxidized LDL cholesterol);
- - regulate blood sugar levels by decreasing the absorption of starches and better regulating carbohydrate metabolism controlled by the liver;
- - prevent oxidative stress and cellular and tissue damage caused by oxidative stress;
- - provide protection of the cardiovascular system by preventing damages to arterial walls and cholesterol deposits that lead to development of atherosclerosis, hence providing prevention from heart attacks and stroke;
- - clean out blood metabolic waster products such as metal ions, glycated proteins, fibrin, etc. which provides support in metabolizing thrombus and hematomas;
- - prevent formation of kidney stones and support kidney function by metabolizing harmful substances ;
- - provide nutrients and support toxin removals, hence preserving joint function and preventing inflammations in individuals with arthritis;
- - prevent anemia, improve hemoglobin levels and energy (by increasing oxygen delivery to tissues);
- - has antimicrobial action that prevents the growth ad kills a range of pathogenic bacteria that cause infections and diseases;
- - prevent growth and proliferation of cancer (malignant) cells;
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