Abstract
Probiotics are live, beneficial microorganisms that offer a wide range of health-promoting effects to the host, such as inhibiting the adhesion and colonization of pathogenic bacteria, enhancing immune responses, neutralizing toxins, alleviating inflammatory bowel conditions, lowering cholesterol levels, contributing to cancer prevention, synthesizing essential vitamins, and producing antimicrobial compounds. Probiotic-enriched food products extend shelf life and improve resilience under adverse environmental conditions. This has led to growing interest in recognizing the vital role of specific microbial strains residing in the intestinal ecosystem. These strains are now widely regarded as probiotics—used both as biotherapeutic agents and as components of functional foods or nutraceutical supplements. This review aims to provide a comprehensive overview of the health benefits of probiotics and their role in disease prevention.
Introduction
History of Probiotics
Elie Metchnikoff, a Russian scientist, Nobel laureate, and professor at the Pasteur Institute in Paris, proposed more than a century ago that lactic acid bacteria (LAB) provided health advantages that could extend life. He proposed that altering the gut microbiota and substituting saccharolytic microorganisms for proteolytic microbes, which generate harmful compounds like phenols, indoles, and ammonia from the digestion of proteins could inhibit “intestinal auto-intoxication” and the ageing that follows. He created a diet consisting of milk fermented by the “Bulgarian bacillus” bacteria. Disorders of the intestinal tract were frequently treated with viable nonpathogenic bacteria to change or replace the intestinal microbiota. In 1917, before Sir Alexander Fleming’s discovery of penicillin, the German professor Alfred Nissle isolated a nonpathogenic strain of Escherichia coli from the feces of a First World War soldier who did not develop enterocolitis during a severe outbreak of shigellosis. The resulting Escherichia coli strain Nissle 1917 is an example of a non-LAB probiotic. In order to treat infants with diarrhoea, Henry Tissier (of the Pasteur Institute) isolated a Bifidobacterium from a breastfed baby. According to his theory, it would displace the diarrhea-causing proteolytic bacteria. To combat diarrhoeal epidemics, Dr. Minoru Shirota discovered the Lacticaseibacillus paracasei strain Shirota in Japan. Since 1935, a probiotic product containing this strain has been sold commercially.
Introduction of Probiotics
Probiotic is a Greek word meaning “for life,” coined by Lilley and Stillwell. Probiotics refer to microbes of non-pathogenic nature that are beneficial to their hosts (Soccol et al., 2014) [85]. Probiotics have been in use for quite a long time as Romans and Greeks, the ancient civilizations developed fermented milk and used it as probiotics, even the bible mentions this sour milk so the concept of probiotics is not entirely new (Hosono, 1992) [41]. Probiotics improve the microbial balance of the Gastrointestinal (GI) tract. World Health Organization (WHO) defines probiotics as “Live microbes which confer a health benefit to their host when administered in adequate amounts” (Chen and Sears, 2015) [22]. Lactobacillus, Bifidobacterium, Enterococcus, Lactococcus, and Streptococcus are most commonly used as probiotics (de Sequeira et al., 2022) [30]. Probiotics exert their beneficial effects through several key mechanisms, including enhancement of the epithelial barrier, promotion of microbial adherence to the intestinal mucosa, inhibition of pathogen adhesion, modulation of the immune system, and induction of biochemical changes that suppress the growth of pathogenic microorganisms (Bermudez-Brito et al., 2012) [13]. Among these biochemical changes is the production of antimicrobial compounds known as bacteriocins, which are proteinaceous in nature and exhibit targeted activity against specific pathogens. In addition to bacteriocins, probiotics also produce short-chain fatty acids (SCFAs), hydrogen peroxide (H₂O₂), and diacetyl compounds that collectively contribute to the modulation of intestinal microflora and confer positive health outcomes (Hawrelak and BNat, 2013) [39]. Nearly all strains of Bifidobacteria and Lactobacilli are capable of producing bacteriocins. Notably, in 2020, the genus Lactobacillus underwent significant taxonomic revision to better reflect the extensive diversity within the group.
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Table 1: Notion with brief definitions
Amit Kumar Jain, Ravindra Kumar Jain, Vinita Katiyar and Upendra Nabh Tripathi, Probiotics: Foods and health friendly microbes, Journal of Current Research in Food Science 2025; 6(2): 46-58, DOI: https://www.doi.org/10.22271/foodsci.2025.v6.i2a.248
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