Although the idea that microbes have a lot of beneficial roles to play on human health isn’t new anymore, none has encapsulated that idea like the discovery of probiotics. The concept of ingesting live microorganisms in order to be healthy does not only sound strange and awkward, but dangerous to some as well. However, probiotics and their health benefits are here to stay, and they are getting due recognition.
Probiotics have been defined by a FAO/WHO Expert Consultation group in 2001 as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.” Probiotics are by definition beneficial to health. Benefits can be nutritional, clinical, medical and treatment-related. To be used as probiotics, it is essential that the organisms must be considered as GRAS (generally recognized as safe), which is a status used to address the problem of pathogen colonization in different ecosystems.
In human nutrition, the most frequently used probiotic microorganisms include Lactobacillus spp., Bifidobacterium spp., Enterococcus spp.; whereas yeast especially Saccharomyces cerevisiae plays a major role in ruminants; while Bacillus spp., Enterococcus spp. and Lactobacillus spp. are more likely to be efficient in pigs and poultry. and in aquaculture practices the commonly used being Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Carnobacterium, Shewanella, Bacillus, Aeromonas, Vibrio, Enterobacter, Pseudomonas, Clostridium, and Saccharomyces species.
But, it is important to note that the health benefits provided by probiotics are strain specific and not species or genus specific. Furthermore, with regards to specific use in humans, probiotics should be able to provide health benefits; promote or maintain the state of well being; and safety assessment should integrate long-term effects and also consider possible chronic effects.
The common sources of probiotics are yogurt, cultured buttermilk, and cheese. The other foods that are produced by bacterial fermentation are Japanese miso, tempeh, sauerkraut, beer, sour dough, bread, chocolate, kimchi, olives, and pickles. Another fermented dairy product is kefir. But among these, the dominant food vehicles for probiotics are still yogurts and fermented milks, both of which provide a relatively low pH environment in which the probiotic bacteria must survive.
However, many studies have shown that probiotic strains are also found in nondairy fermented substrates which includes soy based products, cereals, legumes, cabbage, maize, pearl millet, sorghum, and so forth.
The important criteria which are used for selecting probiotic strains includes that the organism should be:
- non-pathogenic and non-toxic;
- isolated from the same species as its intended host;
- able to survive during transit through the gastrointestinal tract by being acid and bile resistant
- able to adhere and colonize the intestinal epithelium which is an important property for successful immune modulation and competitive exclusion of pathogens
- able to stabilize the normal intestinal microflora;
- able to produce antimicrobial substances like the bacteriocins against the pathogens;
- having a demonstrated beneficial effect on the host;
- durable enough to withstand the duress of commercial manufacturing, processing and distribution;
- and also having good sensory characteristics by not providing unpleasant flavors or textures.
Adapted from “Probiotics – the versatile functional food ingredients” by Gareth Gordon Syngai,Ragupathi Gopi, Rupjyoti Bharali, Sudip Dey, G. M. Alagu Lakshmanan, and Giasuddin Ahmed. J Food Sci Technol. 2016;53(2):921-933.