Probiotics are living microorganisms that at sufficient levels in food are claimed to promote health and wellbeing. Using the term 'probiotic' on a food label implies a relationship between the food and health, and it can be considered to be a health claim. Health claims must adhere to Australian food regulatory standards (Standard 1.2.7 in the Food Standards Code). They must also accurately reflect the underlying scientific evidence of a benefit and not overextend the evidence.
A sizeable array of microorganisms has been proposed as probiotics, including over 50 species of Lactobacillus, 30 species of Bifidobacterium, strains of Streptococcus, other bacteria, and yeasts such as Saccharomyces spp.
In the Food Standards Code, if a yoghurt or fermented milk contains at least 108 cfu/g of the bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus a manufacturer may make a general level claim that the product improves lactose digestion for those individuals who have difficulty digesting lactose. This is called a pre-approved claim, and no other claims are currently allowed for products containing living organisms.
Potentially beneficial organisms have been used as starter cultures in fermented dairy products such as yoghurts and kefir for centuries. While the claim that some strains of these organisms may improve digestion, protect against disease, or enhance immune function, there is a lack of quantitative scientific data.
This is most evident in Europe, where the European Food Safety Authority (EFSA) has so far cautiously approached health claims for probiotics, citing a lack of objective scientific evidence of health and wellbeing benefits. EFSA has identified limitations in data obtained from in vitro, animal and different types of human studies when presented as efficacy substantiation for probiotics
Literature: Probiotics and prebiotics http://www.worldgastroenterology.org/UserFiles/file/guidelines/probiotics-english-2011.pdf