Assessment of Probiotics in Infant Formula and Cereal Based Baby Foods Containing Bifidobacterium lactis Bb12– Update 2014

Abstract

"Assessment of benefits and risks of probiotics in processed cereal-based baby foods supplemented Bifidobacteriumn lactis Bb12" from 2010 answered a request from the Norwegian Food Safety Authority focusing on the age groups 4-6 months, 6-12 months and 1-3 years. However, the use of infant formula intended for newborns, supplemented with this probiotic, was neither asked by the NFSA nor assessed by VKM. The notifier of the baby foods intended for infants and small children has provided information on three different cereal-based products intended for age-groups over 4 months and one infant formula intended for newborns, all supplemented with B. lactis. In its letter the company concludes that their products supplemented with B. lactis do not pose any health and safety risk. Regarding health effect, we have already mentioned in our assessment (Halvorsen et al. 2010) that: "It is not the mandate of this report to evaluate the health claims related to the products as these health claims are assessed by EFSA." Our main conclusions regarding safety were as follows: "No serious adverse events are reported, but neither has the effect of long-term intake of a single bacterial strain been studied. Furthermore, cereals supplemented with B. lactis Bb12 intended for infants and toddlers have not been studied regarding safety. We are not aware of any in vivo studies explicitly concerning the ability of B. lactis Bb12 to influence gene expression of epithelial cells". Furthermore, we were concerned regarding presence of antibiotic resistance gene against tetracycline (tetW) in the B. lactis Bb12. In the answer to the question from NFSA regarding antibiotic resistance gene in L. lactis Bb12, we concluded that: "Consumption of probiotic microorganism B. lactis Bb12 that harbour gene encoding resistance against tetracycline (tetW) may increase the risk of the transfer of such genes to the resident microbiota and pathogenic bacteria and hence increase development of bacterial resistance. High similarity has been observed between tetW gene in bacteria of human and environment origin and B. lactis Bb12. This suggests the spread of tetracycline resistance gene (tetW) between bacteria of various origins. However, the transfer of tetracycline resistance gene (tetW) to other bacteria as a consequence of consumption of Bb12 has not been studied." As we have already mentioned in our assessment (Halvorsen et al. 2010). "It is important to note that the infant's diet comprises a restricted variety of foods, which often are taken several times a day during a period of life when a stable intestinal flora is not yet established. The establishment of a normal intestinal microbiota takes at least two years and thus the intake of large numbers of probiotic bacteria in monoculture during the first years of life may greatly influence this process." According to the "Guideline for evaluation of probiotics in food" (FAO/WHO 2002): ''....the onus is on the producer to prove that any given probiotic strain is not a significant risk with regard to transferable antibiotic resistance or other opportunistic virulence properties." The tet(W) gene in Bifidobacterium seems to be integrated in the chromosome and its surrounding regions vary depending on the strain, but very often the gene is flanked by transposase target sequences or genes coding for transposase, an enzyme that catalyzes the movement of DNA fragments between different locations by recognizing specific target sequences, suggesting that, under adequate conditions, the gene could be transferred (Gueimonde et al. 2013). The presence of a tetracycline resistance gene, tet(W), flanked by a putative transposase gene in B. animalis subsp. lactis was also confirmed in other strains of Bifidobacterium than Bb12 (Stahl & Barrangou 2012).