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Probiotics, mentioned on the labels of food products, often cannot be detected in the food.

May 18, 2001

In the course of a PhD research, fifty-five European probiotic products were screened for the identity and quantity of the bacterial strains included in these products. A probiotic is a living microorganism (bacteria or yeast) that upon intake, improves the health of the host by means of a number of positive effects in that host. These ‘good’ microorganisms that usually belong to the group of the ‘lactic acid bacteria’ (such as Lactobacillus and Bifidobacterium, better known as ‘active bifidus’), can be included in a whole array of products, which then are named ‘probiotic products’. The most popular probiotic products are dairy drinks, although many dried food supplements in the form of powders, capsules en tablets can be found as well.
       In this study, carried out by Robin Temmerman and co-workers at the laboratory of microbiology of Prof. Jean Swings at the Ghent University, twenty-five probiotic dairy products and thirty probiotic dried food supplements were tested for their quality. Tests were performed in order to determine how many and which bacteria were present in these products and if these findings correspond to the information on the label of the concerning products. Making use of a number of specific growth media, it became possible to isolate the bacteria out of the products and cultivate them for further analysis. One of the remarkable findings was that the numbers of bacteria present in the food supplements were substantially lower than it was the case with the dairy products. Of all dried food supplements, thirty-seven percent did not even contain any live bacteria, and the food supplement with the best score reached numbers of up to 1 million bacteria per gram of product. All dairy products contained live bacteria and in most of these products numbers varying from 10 million up to 1 billion bacteria per milliliter of dairy product were recovered. For the majority of the health promoting effects exerted by probiotic bacteria in the large intestine, a rather large number of bacteria are necessary. In addition, many of the bacteria present in the probiotic products become killed when travelling through the stomach and small intestine, so one can presume that the dairy products which, overall, contain a lot more bacteria than the dried food supplements, have a greater chance of realising the proposed effects because more living bacteria reach the large intestine. Nevertheless, there are also a number of health promoting effects that can be carried out by dead bacteria, so it can not be stated that dried food supplements not containing live bacteria will have no beneficial effects for the host. However, the products containing more living bacteria, certainly have a surplus value because they can exert quite a number of good effects that can only be carried out by live bacteria. The reasons for the inferior results of the dried food supplements are most likely that, (i) the bacteria survive better in the liquid matrix of the dairy products, and (ii) that the shelf life of the dried food supplements is too long (appr. 2-3 years compared to 1 month for the dairy products). Also the less favorable storage conditions of the dried food supplements (storage at room temperature) compared to the dairy products is a crucial factor (the cool storage of dairy products at appr. 5°C enhances survival of the bacteria). Anyhow, it is more than desirable that all manufacturers mention clearly on the product label if the bacteria included are dead or alive, and for the latter case, also in what quantities the bacteria are present.
       Furthermore, identification of the isolated bacteria is of the utmost importance and this was performed by determining the protein profiles, unique for each type of bacteria. With these identification data, it became possible to investigate whether the bacteria mentioned on the product label were actually present in the corresponding products. It was found that only 13 percent of both product types contained all claimed bacteria on their labels, and in one third of the products species were isolated, other than those claimed. However, these isolated bacteria still belonged to the group of ‘good’ lactic acid bacteria, so certainly no ‘dangerous’ products are for sale. Nevertheless, the low correspondence between the bacteria claimed on the label and these actually found, indicates a ‘slovenliness’ during the whole production of the products involved. In addition, often scientific incorrect or misleading bacterial names are used on the labels that sound more ‘commercially attractive’. It was also found that the bifidobacteria (mostly indicated on the label as ‘active bifidus’) could only be isolated from only five out of the 24 products claiming these bacteria.
       The correctness of the product label is an absolute necessity to protect the consumers interests. According to our findings, this is where the problem with many of these products is situated. A correct label which contains information about whether or not the bacteria are dead or alive, in what quantities they are included, and the use of their correct scientific name is of the utmost importance; although many products at present fail to do so.


Ghent University