Kefir-A Natural Fermented Probiotic-An Updated Review

 Corresponding author: Ravindra B. Malabadi Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Kefir-A Natural Fermented Probiotic-An Updated Review Raju K. Chalannavar 1, Shreya S. Hosur 2, Divakar MS 3 and Ravindra B. Malabadi 1, 4 * 1Department of Applied Botany, Mangalore University, Mangalagangotri-574199, Mangalore, Karnataka State, India. 2 Department of Chemical engineering, National Institute of Technology Karnataka (NITK), Surathkal, Mangalore575025, Karnataka State, India 3 Food Science and Nutrition, Department of Biosciences, Mangalore University, Mangalagangotri574199, Karnataka State, India 4 Miller Blvd, NW, Edmonton, Alberta, Canada. World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 Publication history: Received on 10 September 2025; revised on 20 October 2025; accepted on 25 October 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.28.1.3640 Abstract Kefir, the traditional beverage, is now recognized as a potential source of probiotics and molecules with highly interesting healthy properties. These grains are a reusable starter for a continuous fermentation cycle. Kefir grains are hard granules resembling cauliflower florets in appearance that vary from 0.3 to 3.5 cm in size. The microorganisms in the kefir grains produce lactic acid, antibiotics and bactericides, which inhibit the development of degrading and pathogenic microorganisms in kefir milk. Based on the fermenting substrate, kefir is categorized as dairy (milk) and non-dairy (water). In kefir grains the main polysaccharide is Kefiran, which is a heteropolysaccharide composed by equal proportions of glucose and galactose and is mainly produced by Lactobacillus kefiranofaciens. The kefir market consists of sales of kefir grains, kefir milk, kefir yogurt, kefir smoothie, kefir probiotic drink. Kefir’s has a remarkable antimicrobial, anti-inflammatory, anticancer, antioxidant, and anti-diabetic properties attributed to the synergistic effect of kefir peptides, immune and cytokine modulatory properties and free radical scavenging effects. Keywords: Anti-Cancer; Antioxidant; Kefir; Milk Kefir; Kefiran; Lactobacillus kefiranofaciens; Probiotics; Water Kefir 1. Introduction Kefir is a naturally fermented milk drink with rich probiotic content [1-67-108-150]. Among the emerging functional foods, probiotic-based foods and beverages are becoming one of the most acceptable to consumers [1-43-108]. Traditionally, fermented foods have been shown to contain probiotic microorganisms [1-70]. Probiotics are defined as live microorganisms which when administered in adequate quantity confer health benefits to the host [67-73]. Probiotic bacteria, generally incorporated into fermented dairy products, mainly belong to the genera Lactobacillus and Bifidobacterium [67-73]. One of the important criteria used for the selection of probiotic microorganisms must be able to survive in the gastrointestinal environment and to present at least one beneficial function (colonization resistance, immunomodulation or nutritional contribution) [67-73]. In other words,probiotics are defined as food or pharmaceutical preparations containing live non-pathogenic microorganisms which improve one of the three main beneficial functions (colonization resistance, immunomodulation or nutritional contribution) of the normal gastrointestinal microbiota, when ingested by human or animal hosts [67-73-150]. The gut microbiome refers to the vast community of microorganisms, including bacteria, viruses, fungi, and other microbes, that live in the digestive tract [67-73-108-150]. This complex ecosystem plays a vital role in human health, influencing digestion, immune function, and even brain health [67-73-108-150]. World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 2287 Kefir grains are not actual grains, but a living culture of yeast [145-147] and bacteria that look like small, soft, white cauliflower florets [1-67-108]. They are used to ferment milk into a tangy, probiotic drink called kefir by breaking down the lactose and producing lactic acid [1-67-108-150]. These grains are a reusable starter for a continuous fermentation cycle. Kefir grains are hard granules resembling cauliflower florets in appearance that vary from 0.3 to 3.5 cm in size [1-65-99-150]. Traditionally, kefir is manufactured using cow, goat, camel, donkey and buffalo milk [1-40108]. Milk kefir grains are small white gelatinous balls that visually resemble small cauliflowers clumped together[150]. Kefir, the traditional beverage, is now recognized as a potential source of probiotics and molecules with highly interesting healthy properties[1-40-108-150]. Kefir is an acidic-alcoholic fermented milk product with little acidic taste and creamy consistency that was originated in the Balkans, in Eastern Europe, and in the Caucasus [1-67]. Kefir is an acid-alcoholic fermented milk drink that has been consumed since ancient times in The Caucasus mountains regions of Asia [1-67-108-150]. According to the study conducted by Azhar and Munaim (2019) [67], the majority of the bacterial and yeast strains that can be found in the kefir drink in Malaysia are Lactobacillus and Saccharomyces that are recognized as probiotic microorganisms [67]. In Malaysia, Kefir drink is a product from the fermentation process of milk using symbiotic mixture of bacteria and yeast consortium [67]. Saccharomyces and Lactobacillus are the major genera found in the kefir drink [67]. Kefir drink is a product that undergoes a fermentation process using milk as a medium [67]. The taste is quite acidic and it has a creamy-like texture [67]. It is normally produced from a traditional kefir grains or kefir starter cultures by fermentation process [67]. Tingirikari et al., (2024) [9] reported that Kefir comprises a microbial symbiotic mixture of bacteria and yeast that attached to a polysaccharide matrix [9-67-108-135]. Although the bacterial population is dominant in kefir, the presence of yeast plays an important role to develop the flavors as well as chemical composition of the kefir product [67-108-150]. Kefir is creamy in texture and tastes slightly sour and acidic. It is now a widely consumed beverage worldwide, mostly in Eastern and Northern Europe and Japan[1-60-108]. The term kefir is derived from the Turkish word “keyif” meaning “good feeling”, in reference to the emotions one has after consuming the drink [1-46-108-150]. Kefir is differentiated into two main types, namely traditional and industrial kefir, based on the process of its production method[1-50]. The key difference between these methods lies in the process of inoculation of kefir grains or starter culture in the milk [140-108]. In the traditional method, kefir varies in microbial content and sensory properties due to its origin, storage, and handling conditions [1-57-108]. In contrast, industrial methods rely on standard starter cultures and precise environmental conditions to ensure that every batch has the same microbial content and sensory properties [1-37-108]. Traditional kefir preparation involves fermenting milk using kefir grains, a starter culture of yellowish, tiny, amorphous, and gelatinous form [1-28-108-150]. Some studies suggest that probiotic bacteria in kefir consumers’ influence gut microbiota which are abundant and are correlated with health improvement [1-93-108]. Hence, it had been demonstrated that the cell-free fraction of kefir enhances the ability to digest lactose relieving symptoms[1-73-108]. Another reason for the increased interest in probiotic strains from kefir is its capacity to lower cholesterol levels [143-108-150]. 2. Indian Probiotic Food Some of the top Indian probiotic foods and drinks which can have daily consumption for a healthy gut: 1. Curd (Dahi) 2. Buttermilk (Chaas) 3. Kanji Lassi. 4 Kefir milk 5. Idli / Dosa 6. Dhokla 7. Handvo 8. Appam 9. Khusha 10. Khambral (Kombucha) 11. Pickles (Achaar) 12. Sauerkraut (Homemade) 13. Pakhala / Panta Bhat 14. Fermented Soy (Tempeh/Natto) 15. Khaman 16. Fermented Porridge 17. Kimchi (Indian-style) 18. Fermented Peanut Chutney 19. Ragi Malt (Fermented) 20. Kefir grains(Homemade) [67-73]. Indian companies which are selling kefir grains include, KefirWala and indiaweightlosskefir.com [1-67]. These companies sell both water and milk kefir grains, which can be purchased online for home fermentation. Other options may include online marketplaces like Amazon India[6773]. All these probiotic foods maintain the balance of gut bacteria, strengthen immunity, and ensure overall health, making them simple and effective inclusions in our daily diet for improved gut health [67-73]. 3. International Kefir Brands Some of the best International kefir brands [11-14] include Lifeway, Maple Hill Creamery, and Wallaby Organic for a wide variety of options, while Redwood Hill Farms and Green Valley Organics are good choices for those with sensitivities to cow's milk [11-14]. Major companies operating in the kefir market include Danone SA, Lifeway Foods Inc., Nestle SA, Fresh Made, Maple Hill Creamery LLC, The Hain Celestial Group Inc., Green Valley Organics, Wallaby Yogurt Company, Biotiful Dairy Ltd., Redwood Hill Farm & Creamery Inc., Babushka Kefir, Greek Gods Yogurt, GO-KEFIR, Nancy's Probiotic Foods, Yofix Probiotics Ltd., Grace Harbor Farms, Forager Project LLC, Rumba Kefir, Organic Meadow World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 2288 Limited Partnership, Oak Knoll Dairy, Oy Elopak Ab, Latta Buildtech Private Ltd., Güvenç A.S, Kri Kri Milk Industry SA, New Age Farm Inc., One Straw Farm, Lifeway Foods Canada Inc., Granarolo S.p.A, Good Karma Foods Inc., The Icelandic Milk and Skyr Corporation, and Green Mountain Creamery LLC [11-14]. 4. Kefir Production Kefir can be produced through diverse methodologies, including: (1) traditional manufacturing, entailing the fermentation of milk with kefir grains; (2) a Russian or European approach; and (3) industrial-scale production, wherein kefir is fermented by the direct incorporation of commercial starter cultures into milk. Kefir can be produced by fermenting milk with commercial freeze-dried kefir starter cultures, traditional kefir grains, and the product that remains after the removal of kefir grains [1-73-108-135]. Kefir grains are a kind of yogurt starter, which are white to yellow – white, gelatinous, and variable in size (varying from 0.3–3.5 cm in diameter) and are composed by a microbial symbiotic mixture of lactic acid bacteria (108 CFU/g), yeast (106–107 CFU/g), and acetic acid bacteria (105 CFU/g) that stick to a polysaccharide matrix [1-69-108-150]. After successive fermentations, kefir grains can break up to new generation grains, which have the same characteristics as the old ones [1-73-108-135]. These grains are used to turn milk into milk kefir, a fermented drink that is full of probiotics and is said to have many health benefits[1-73]. These strange little clumps house a jungle of beneficial bacteria and yeast that live in symbiosis and are activated when mixed with milk to create creamy, tangy, and slightly fizzy milk kefir [1-73-150]. Once the kefir has been produced, the grains can be collected and put into fresh milk to start a new kefir fermentation[1-73]. Kefir grains are the living symbiotic colonies of yeast and bacteria that convert milk into the probiotic powerhouse that is milk kefir[1-73-135]. As the kefir grains digest the lactose in the milk, they create that tangy, creamy taste and texture that makes milk kefir[1-73-108135-150]. In addition, Bifidobacterium sp., Lactobacillus sp. and probiotic yeast (Saccharomyces boulardii) may be used as adjunct cultures when blended with kefir grains or kefir DVI cultures [1-73-150]. On the other hand, whey may be a practical base for kefir culture production, and fermented whey has shown to be a suitable cryoprotective medium during freezedrying[1-73-108]. The consumption of this fermented milk has been related to a variety of health benefits. Kefir may not only be a natural probiotic beverage, but also acts as an effective matrix for the delivery of probiotic microorganisms[1-73-108-150]. Due to its composition, kefir is mainly considered a probiotic resource [1-73-108135]. These grains are usually composed of diverse combinations of bacterial species, including lactic acid bacteria (108 CFU/g) such as Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, Carnobacterium, and acetic acid bacteria (105 CFU/g) such as Acetobacter cerevisiae, Acetobacter pasteurianus, and yeast (104–106 CFU/g) [1-67-108]. Kefir grains are kept viable by maintaining a high bacteria–yeast ratio, which is accomplished by ongoing fermentation cycles that increase the biomass of grains depending on different factors, such as pH, temperature, washing, milk renewal, and availability of nutrients [1-69-108-150]. After a series of successful fermentation processes, kefir grains divide into new grains with the same microbial traits as the originals [1-68-108-150]. To produce kefir in household conditions, kefir grain preservation can be accomplished either by continuous fermentation cycles or 10 weeks of multiplication of biomass growth [1-73]. Some studies have shown that kefir grains and fermentation time directly impact the properties of the drink. Kefir grain concentrations of 3–5% were found to be optimal for yielding the lactic acid bacteria and protein levels [1-73-108-150]. Additionally, 18 h, 21 h, and 24 h fermentation times have been known to change the intensity of microbial activity and chemical composition of milk, which can influence the quality of the end product [1-73-108150]. 5. Types of Kefir Based on the fermenting substrate, kefir is categorized as dairy (milk) and non-dairy (water) [1-59-108-150]. However, milk and water kefir grains are traditionally blended with a vast symbiotic microbial consortiums and exhibit striking similarities in terms of characteristic structure, associated microbial composition, and metabolites [1-70-108-150]. Milk kefir yields substantial quantities of protein, probiotics, and prebiotics[1-59-108-135-150]. In contrast, water kefir emerges as a crucial reservoir of probiotics, prebiotics, and antioxidants, particularly catering to the dietary needs of vegans and individuals with dairy allergies or intolerances [1-59-108-150]. Both milk and water kefir are produced through the inoculation of the kefir grain as starter culture into sub strates (milk or water-based solutions enriched with fruits, vegetables, and sugar sources) at variable proportions (ranging up to 20% w/v) and fermenting for 24 h at a varying temperature of 20–40 °C [1-70-108-150]. Upon completion of the fermentation, kefir grains are then separated from the beverage through filtration and can be reused for subsequent inoculations [1-38-108-150]. In dairy Kefir, milk sourced from various ruminants (cows, sheep, goats, buffalo, or camels, donkey) serves as a substrate for World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 2289 fermentation [1-56-108-150]. Milk kefir is a cultured dairy product obtained from the symbiotic interaction between kefir grains and milk, resulting in a fermented beverage [1-60-108]. The granular composition of milk kefir is characterized by small, creamy, yellowish-to-white structures resembling cauliflower florets in an irregular and lobed shape, with a diameter ranging between 0.1 and 0.2 cm [1-47-108-135-150]. The characteristic microbiota in milk kefir comprises Lactobacillus kefiranofaciens, Lactobacillus. kefiri, Lactobacillus. parakefiri, and Lactobacillus kefirgranum [149-108-135]. LAB are introduced into milk to initiate the process [1-67-108-150]. These microorganisms enzymatically convert lactose into lactic acid, leading to a reduction in pH. Thus, LAB influence the sensory attributes and extended shelf life of fermented milk [1-46-108-150]. On the other hand, water kefir grains are fermented with water substrate in a saccharine medium, with brown sugar serving as a primary substrate, whereas other auxiliary substrates include fruit juices (e.g., grape, pomegranate, apple, pineapple, and melon), vegetables (e.g., onion, ginger, soybean, and carrot), and molasses (e.g., honey, sugarcane) [1-26, 27-70-108-135]. Water kefir grains, are also known as “Tibi or Tibico,” “Sugary kefir grains,” “Japanese water crystals,” and “Graines Vivantes,” contain a dextran matrix [1-49-108-135]. The predominant microbiota accountable for the synthesis of the dextran structure in water kefir grains includes Lactobacillus sp. Lactobacillus casei, Lactobacillus nagelii, Lactobacillus hilgardii, Lactobacillus hordei, and Leuconostoc mesenteroides [1-50–54-67-108]. The fermentation process of non-dairy (water) kefir is facilitated by kefir grains, which comprise a conglomerate of acetic acid bacteria, yeast, predominantly Saccharomyces, Candida, and Kluyveromyces, as well as LAB, encompassing the species, Leuconostoc, Lactobacillus, Streptococcus, Oenococcus, Pediococcus, Enterococcus, and Lactococcus [1-67-108-150]. Water kefir harbours an estimated composition of around 70–75% Lactobacillus sp., 10–12% Leuconostoc sp., 8–10% Acetobacter sp., 5–7% Bifidobacterium sp., and 3–5% other bacterial species, and as compared to dairy kefir, water kefir nurtures more genera of yeast (like species of Guehomyces, Kloeckera, and Hanseniaspora) [1-60-108-150]. 6. Microbial Composition of Kefir grains In recent decades, a global shift in lifestyle and the ubiquitous consumption of junk foods have led to dysbiosis and other metabolic disorders significantly impacting human health [1-9-108-150]. Recent studies performed on traditional foods have shown several health benefits and have gained the attention of the scientific community towards ethnic foods [1-99-135]. In this regard, the consumption of ethnic foods with symbiotic properties is increasing gradually across the globe[1-90]. Kefir is a thick, sour, and sometimes slightly spritzy fermented milk drink produced through the action of the bacteria and fungi within kefir ‘grains’, a classic example of a SCOBY (Symbiotic Community of Bacteria and Yeasts) [1-67-108]. The microbial diversity of kefir samples collected from a wide geographical area has been reported and discussed [1-63]. The distribution of yeast and bacteria in the Indian kefir grains, like other kefir grains, are a complex symbiotic mixture of lactic acid bacteria, yeasts, and acetic acid bacteria held together by a unique polysaccharide matrix [1-67-108-150]. The key bacterial genera include Lactobacillus, Lactococcus, Leuconostoc, and Acetobacter, while common yeasts include Kluyveromyces and Saccharomyces species [1-60-108-150]. The specific microbial composition can vary based on the grain's origin and production methods [1-68-144-150]. Kefir grains have a complex composition of microbial species such as the predominance of lactic acid bacteria, acetic bacteria, yeasts, and fungi [1-67-108]. This microbial species are classified into four groups: homofermentative and heterofermentative lactic acid bacteria and lactose and non-lactose assimilating yeast [1-63]. In that way, Lactobacillus paracasei ssp. paracasei, Lactobacillus acidophilus, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus plantarum, and L. kefiranofaciens are predominant species[1-63108-150] However, these species represent only 20% of the Lactobacillus in the final fermented beverage, with the remainder consisting of Lactobacillus kefiri (80%), Acetobacter aceti and A. rasens have also been isolated, such as the fungus Geotrichum candidum [1-63-108]. More than 23 different yeast species have been isolated from kefir grains and from fermented beverages of different origins [1-69-108-150]. However, the predominant species are Saccharomyces cerevisiae, S. unisporus, Candida kefyr, and Kluyveromyces marxianus ssp. marxianus [1-73-108-135]. There is a symbiotic relation between the microorganisms present in kefir grains, wherein the bacteria and yeast survive and share their bioproducts as power sources and microbial growth factors [1-69-103-150]. This microorganism association is responsible for lactic and alcoholic fermentation [1-73-108-150]. The microbial composition may vary according to kefir origin, the substrate used in the fermentation process and the culture maintenance methods [1-69108-150]. Tibetan kefir, which is used in China, is composed of Lactobacillus, Lactococcus, and yeast. Additionally, acetic acid bacteria have been identified in Tibetan kefir, depending on the region in China from where it was obtained, Tibetan kefir composition differs from that of Russian kefir, Irish kefir, Taiwan kefir, Turkey fermented beverage with kefir [1-63-106-150]. However, it is known that this microbial diversity is responsible for the physicochemical features and biological activities of each kefir [1-69-108-150]. World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 2290 7. Chemical Activity of Kefir On the basis of literature survey, probiotics present in milk kefir generate different chemical metabolites that have hypocholesterolemic, antimicrobial, antihypertensive, anti-inflammatory, antioxidant, and anticarcinogenic actions and are generally beneficial to human health [1-67-108-150]. Kefir has been shown to possess antibacterial properties against a variety of microbes [1-57-135-150]. The microorganisms in the kefir grains produce lactic acid, antibiotics and bactericides, which inhibit the development of degrading and pathogenic microorganisms in kefir milk [1-68-108-135-150]. Kefir acts against the pathogenic bacteria Salmonella, Helicobacter, Shigella, Staphylococcus, Escherichia coli, Enterobacter aerogenes, Proteus vulgaris, Bacillus subtilis, Micrococcus luteus, Listeria monocytogenes, Streptococcus pyrogenes, Streptococcus faecalis KR6, Fusarium graminearum CZ1, and the fungus Candida albicans [1-69-108-135-150]. On the other hand, it has been demonstrated that a mixture of kefir isolated bacteria and yeast is able to prevent diarrhea and enterocolitis triggered by Clostridium difficile [1-608-108-150]. Besides, kefir showed good efficacy in inhibiting spore formation and aflatoxin B1 produced by the fungus Aspergillus flavus, which is a toxic compound formed either in the field or during food storage[1-69-108]. Therefore, kefir appears as a promising safe alternative natural food preservative offering protection against intoxication with aflatoxin B1[1-67-108-150]. It had been proved that many species of lactobacilli present in kefir have S-layer proteins. Surface layers (S-layers) can be aligned in unit cells on the outermost surface of many prokaryotic microorganisms [1-67-108-150]. It has been demonstrated that these S-layer proteins can apply a protective action inhibiting the grown of Salmonella enterica serovar Enteritidis in Caco-2 cells, and also have the ability to antagonize the effects of toxins from Clostridium difficile on eukaryotic/eukaryotic cells in vitro [1-67-108-150]. However, there are other important bioactivities that have been tested with kefir grains, the cell-free fraction of kefir or acid lactic bacteria isolated from kefir, such as antitumoral, anti-inflammatory, antimicrobial immunoregulatory, antiallergenic, wound healing, antidiabetic, antimutagenic and antigenotoxic [1-67-108-135]. Hence, it had been demonstrated that kefir cell-free fraction has antiproliferative effects on human gastric cancer SGC7901 cells, colon adenocarcinoma cells, HuT–102 malignant T lymphocytes, sarcoma 180 in mice, Lewis lung carcinoma and human mammary cancer , and reduce oxidative stress [1-67-108-144-150]. Another study has shown that suspensions after 24 h fermentation and mechanically disintegrated kefir grains cause a significant inhibition of granuloma tissue formation and a 43% inhibition of the inflammatory process [1-67-108-150]. The increased search for natural polysaccharides has been very significant due to their use in the food, pharmaceutical, and cosmetic industries as additives, bio-absorbents, metal removal agents, bioflocculants, and medicine delivery agents, among other functions [1-67-108-150]. Many microorganisms, such as bacteria, fungi, and weeds, have the capacity/ability to synthesize and excrete extracellular polysaccharides, and these polysaccharides can be either soluble or insoluble [1-67-108-150]. The polysaccharides that are commonly used as food additives are xanthan, dextran, gellan, and alginates, while the exopolysaccharides (EPSs) produced by lactic acid bacteria show good physicochemical characteristics for their use as food additives [1-67-108-150]. In addition to these characteristics, EPSs are obtained from microorganisms classified as GRAS (generally recognized as safe), such as lactic acid bacteria [1-67-108-135-150]. The EPS kefiran is produced by Lactobacillus kefiranofaciens from kefir grains, which are composed of proteins, polysaccharides, and a complex symbiotic microbial mixture [1-67-108-150]. These microorganisms grow in kefiran, which is a polysaccharide matrix consisting of glucose and galactose [1-67-108-135-150]. Despite good kefiran production by L. kefiranofaciens alone, it has been observed that the addition of Saccharomyces sp. to the culture improves the net quantity of kefiran, illustrating the importance of the symbiosis between the bacteria and yeast that are present in kefir [1-57-108-150]. actic acid bacteria can synthesize homopolysaccharides or heteropolysaccharides[1-67-135]. The synthesized homopolysaccharides are glucans or fructans, which are composed of only one type of monosaccharide (glucose or fructose, respectively), whereas the heteropolysaccharides contain different types of monosaccharides in different proportions (mainly glucose, galactose, and rhamnose), [1-67-108-150]. Similarly to lactic acid bacteria, Lactobacillus sp. also produces glucan and fructan [1-67-108-150]. The homopolysaccharides show a much higher performance compared with heteropolysaccharide production [1-67-108]. The heteropolysaccharides excreted by Lactobacillus delbrueckii, Lactobacillus bulgaricus, Lactobacillus rhamnosus, and Lactobacillus helveticus contain galactose, glucose, and rhamnose as the main monosaccharides, with other monosaccharides being present in smaller concentrations[1-67-107-150]. They are also highly branched with different types of linkages, and their denominations are complex and generally dependent on the main monosaccharide[1-67108-150]. Lactobacillus plantarum isolated from Tibetan kefir excretes EPS classified as heteropolysaccharides composed of galactose, glucose, and mannose [1-67-108-150]. This EPS has the capacity/ability to reduce blood cholesterol and form World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 2291 a biofilm shape [1-67-108-150]. Kefiran is an EPS classified as a heteropolysaccharide comprising glucose and galactose in high concentrations, and it is classified as a water-soluble glucogalactan, which makes it suitable to be used as an additive [1-67-106]. Kefiran has excellent rheological properties and can significantly improve the viscosity of lacteous products by favoring and maintaining gel properties and avoiding the loss of water during storage [1-67-108-135]. With respect to the biological activity of kefiran, several studies have demonstrated that this EPS can be used as a nutraceutical [1-67-107-150]. 8. The Polysaccharide Kefiran In kefir grains, the main polysaccharide is kefiran, which is a heteropolysaccharide composed by equal proportions of glucose and galactose and is mainly produced by Lactobacillus kefiranofaciens [1-67-108-144-150]. It has been demonstrated that kefiran improves the viscosity and viscoelastic properties of acid milk gels, and is able to form gels that have interesting viscoelastic properties at low temperatures [1-67-108-150]. Therefore, kefiran can also be used as an additive in fermented products [1-67-108]. Besides, kefiran can enhance the rheological properties of chemically acidified skim milk gels increasing their apparent viscosity[1-47-108-150]. Compared with other polysaccharides, kefiran has outstanding advantages such as antitumor, antifungal, antibacterial properties immunomodulation or epithelium protection, anti-inflammatory, healing, and antioxidant activity [1-67-108]. Kefir refers to a fermented milk drink made from kefir grains, which are a combination of bacteria and yeast [1-67-108-144-150]. This probiotic beverage has a tangy flavor and a creamy texture, similar to yogurt but usually thinner [1-67-108-135]. It is rich in beneficial probiotics, vitamins, and minerals, and is known for its potential health benefits, including improved digestion and immune support [1-67-108, 144-150]. It can be consumed on its own or used in smoothies, salad dressings, and various recipes[ 1-97]. For further insights on this market, Kefir grains offer numerous health benefits, including boosting the immune system, alleviating digestive issues, and enhancing antimicrobial activity [1-67-108-144-150]. They are rich in beneficial probiotic bacteria that promote gut health and support a balanced intestinal microbiota [167-108]. “Beta-lactoglobulin (β-lg), a well-known milk protein,” is used to create nanofibril structures that can serve as scaffolds [1-67-108-144-150]. Kefiran, the EPS of kefir, has very important physicochemical and rheological properties. Besides, its biological properties suggest its use as antioxidant, antitumor agent, antimicrobial agent, and immunomodulator [1-67-108-150]. 9. Health Benifits of Kefir Due to changes in lifestyle and food behavior, the global burden of diseases is increasing, significantly affecting human health leading to dysbiosis and several metabolic and non-metabolic-related disorders [1-65-108-150]. In the past decade, functional foods have gained considerable attention from the scientific community[1-65-108]. The exploration of both dairy and water kefir, their production methodologies, and their microbial compositions has provided valuable insights into the diversity of this ethnic fermented beverage[1-45-108-135-150]. Unlike traditional dairy kefir, nondairy kefir is highly suitable for individuals with lactose intolerance, vegan dietary preferences, or dairy allergies [1-35108-144]. Furthermore, compelling evidence supports kefir’s remarkable antimicrobial, anti-inflammatory, anticancer, antioxidant, and anti-diabetic properties attributed to the synergistic effect of kefir peptides, immune and cytokine modulatory properties and free radical scavenging effects[1-65-108-150]. The antimicrobial efficacy of kefir is attributed to the presence of LAB [1-65-108]. These microorganisms actively engage in competition with pathogens for nutrients. Additionally, kefir fermentation triggers the endogenous synthesis of organic acids (specifically lactic and acetic acid), CO2, acetaldehyde, bacteriocins, cathelicidin, and H2O2 [1-65-108144]. Supplementation of kefir has been reported to reduce the glycemia and enhance the equilibrium between proand anti-inflammatory cytokines, as indicated by the modulation of interleukin-1(IL-1), IL-6, and the tumor necrosis factor (TNF)/IL-10 ratio [1-71-108-150]. The potential of kefir and its fractions as adjunctive components in cancer therapy has been reported [1-65-108]. Kefir exhibits robust antioxidant in both ex vivo and in situ studies model [165-108-144]. Probiotics present in kefir have the potential to stimulate the gut microbiota to generate insulinotropic polypeptides and glucagon-like peptide, thereby inducing glucose uptake by muscular tissues [9-65-108]. The antidiabetic potential of kefir depends on the substrate and fermentation technique employed [9-11-67-108-144-150]. Furthermore, the glucose-lowering effect of kefir may be attributed to its antioxidant activity, that eventually contribute to the regulation of blood sugar or the reduction of glucose absorption in the gastrointestinal tract [1-67-108-150]. 10. Kefir Market Reports The kefir market size has grown strongly in recent years. It will grow from $2.49 billion in 2024 to $2.62 billion in 2025 at a compound annual growth rate (CAGR) of 5.2%. Kefir refers to a fermented milk drink made from kefir World Journal of Advanced Research and Reviews, 2025, 28(01), 2286–2299 2292 grains, which are a combination of bacteria and yeast [11-14]. This probiotic beverage has a tangy flavor and a creamy texture, similar to yogurt but usually thinner [1-11-14-70]. It is rich in beneficial probiotics, vitamins, and minerals, and is known for its potential health benefits, including improved digestion and immune support[1-11-14-70]. It can be consumed on its own or used in smoothies, salad dressings, and various recipes [1-11-14-70]. The main types of kefir include milk kefir and water kefir, which are sourced from animal milk, soy milk, coconut milk and others [1-1114-70-108]. Milk kefir refers to a fermented dairy product and is made by adding the culture to the milk and keeping it warm like yogurt [1-11-14-70-108]. Milk kefir is high in probiotics and aids digestion. The sourced from organic and conventional ingredients, and available in both flavored and unflavored categories [1-11-14-70-108]. These products are distributed through supermarkets/hypermarkets, convenience stores, specialty stores, and other distribution channels [11-14-67]. The growing popularity of functional beverages will propel the Kefir market [11-14-67]. The demand for nutrient-rich drinks, sugar-free products, and non-dairy products lead to the Kefir market growth [11-14]. Therefore, the rising demand for functional beverages will drive the kefir industry [11-14]. Drinkable kefir refers to the liquid form meant for direct consumption, while spoonable kefir is thicker and often consumed with a spoon, similar to yogurt [11-14]. For instance, in September 2024, Activia, an India-based company that operates in the fast-paced consumer goods sector, launched a new range of spoonable and drinkable kefir to enhance gut health[11-14]. A new kefir range offers both drinkable and spoonable options for gut health. Available in Natural and Strawberry & Raspberry flavors, it features 16 live culture strains to promote digestive wellness [1114]. The kefir is enriched with calcium and crafted for a smooth texture and mild taste [11-14]. It aims to provide an accessible and enjoyable gut health experience [11-14]. North America was the largest region in the kefir market in 2024 [11-14-150]. Asia-Pacific is expected to be the fastest-growing region in the kefir market share during the forecast period [11-14]. The regions covered in this market report include Asia-Pacific, Western Europe, Eastern Europe, North America, South America, Middle East and Africa[11-14]. The countries covered in this market report include Australia, Brazil, China, France, Germany, India, Indonesia, Japan, Russia, South Korea, UK, USA, Italy, Spain, Canada [11-14]. Milk kefir grains are concentrated symbiotic cultures of lactic acid bacteria and yeasts [1-67-108]. Innovation is focused on improving grain viability, shelf life (particularly for dehydrated grains), and developing valueadded products like flavored kefir or kefir-based drinks[1-11-14-70-108]. The kefir market consists of sales of kefir grains, kefir milk, kefir yogurt, kefir smoothie, kefir probiotic drink [1-67]. Key players in the market include Cultures for Health, Freshly Fermented, Kombucha Kamp, Happy Kombucha, Symbiota, Crafty Cultures, and Poseymom, each vying to capture a share of this burgeoning market [11-14]. The global milk kefir grain market is experiencing robust growth, driven by increasing consumer awareness of its health benefits and the rising popularity of fermented foods and beverages [11-14]. The market size in 2025 is estimated at $150 million, projecting a Compound Annual Growth Rate (CAGR) of 12% from 2025 to 2033 [11-14-108]. This significant growth is fueled by several key trends, including the increasing demand for functional foods with probiotics and prebiotics, a growing preference for natural and organic products, and the expansion of online sales channels that provide convenient access to kefir grains[11-14]. 11. Conclusion Kefir is a naturally fermented food that is rich in probiotics. Probiotics are microbial cell preparations or components of microbial cells with a beneficial effect on the health of the host. Kefir is one such ethnic food with excellent functional properties. It is a unique traditional fermented drink comprised of kefir grains and probiotic microbes. Kefir grains are a gelatinous consortium of casein, milk solids coupled with yeasts, and lactobacilli rich microbiota embedded in a polysaccharide matrix. These components act as starters, initiating fermentation when introduced into fresh milk. This beverage of symbiotic benefits, encompassing improved gut health and preventing several metabolic and other diseases through various biological mechanisms. Despite its millennia long history, it has recently gained prominence due to emerging biotechnological and nutraceutical applications. Kefir has been acknowledged as a beneficial functional food with alternative therapeutic potential, and further studies on this topic are particularly important. 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