Probiotic
Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota.[1][2]
Probiotics are considered generally safe to consume, but may cause bacteria-host interactions and unwanted side effects in rare cases.[3][4][5]
There is some evidence that probiotics are beneficial for some conditions, but there is little evidence for many of the health benefits claimed for them.[1]
The first discovered probiotic was a certain strain of bacillus in Bulgarian yoghurt, called Lactobacillus bulgaricus.
The discovery was made in 1905 by Bulgarian physician and microbiologist Stamen Grigorov.
The modern-day theory is generally attributed to Russian Nobel laureate Élie Metchnikoff, who postulated around 1907 that yoghurt-consuming Bulgarian peasants lived longer.[6]
A growing probiotics market has led to the need for stricter requirements for scientific substantiation of putative benefits conferred by microorganisms claimed to be probiotic.[7]
Although numerous claimed benefits are marketed towards using consumer probiotic products, such as reducing gastrointestinal discomfort, improving immune health,[8] relieving constipation, or avoiding the common cold, such claims are not supported by scientific evidence,[7][9][10] and are prohibited as deceptive advertising in the United States by the Federal Trade Commission.[11]
As of 2019, numerous applications for approval of health claims by European manufacturers of probiotic dietary supplements have been rejected by the European Food Safety Authority for insufficient evidence of beneficial mechanism or efficacy.[8][12]
In food
Live probiotic cultures are part of fermented dairy products, other fermented foods, and probiotic-fortified foods.[19]
Additionally, lactic acid bacteria (LABs), which are food fermenting bacteria, have the ability to prevent food spoilage and can improve the nutritive value of the foods they inhabit.
Also due to its low cost and low energy requirements when processing and preparing foods, acid fermentation, combined with salting, remains one of the most practical methods of preservation of fresh vegetables, cereal gruels, and milk-cereal mixtures.[20]
Fermented products that contain lactic acid bacteria include
vegetables such as pickled vegetables,[21]
kimchi,[21][22]
pao cai,[23] and
sauerkraut;[24]
sourdough bread or bread-like products made without wheat or rye flour,
amino acid/peptide meat-flavored sauces and pastes produced by fermentation of cereals and legumes;
fermented cereal-fish-shrimp mixtures and fermented meats;[20]
soy products such as tempeh,[25]
miso,[26] and
soy sauce;[27]
dairy products such as
kefir,[28]
buttermilk;[29] and
non-dairy products such as
bee pollen.[30]
More precisely, sauerkraut contains the bacteria Leuconostoc mesenteroides, Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus brevis, Leuconostoc citreum, Leuconostoc argentinum, Lactobacillus paraplantarum, Lactobacillus coryniformis, andWeissella spp.[31] Kimchi contains the bacteria Leuconostoc spp., Weissella spp., andLactobacillus spp. Pao cai contains L. pentosus, L. plantarum , Leuconostoc mesenteroides , L. brevis, L. lactis, and L. fermentum. A list of many other bacteria found in several Asian fermented fruits and vegetables also is available.[32][33] Kefir contains Lactobacillus acidophilus, Bifidobacterium bifidum, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, Lactobacillus kefiranofaciens, Lactococcus lactis, and Leuconostocspecies.[34][35] Buttermilk contains either Lactococcus lactis or L. bulgaricus.
Other acidic bacteria, said to be probiotic,[36][37] also can be found in kombucha. This drink contains Gluconacetobacter xylinus.[38][39] It also containsZygosaccharomyces sp.,Acetobacter pasteurianus, Acetobacter aceti, and Gluconobacter oxydans.[40]