The importance of gut bacteria in averting childhood allergies

The prevalence of asthma and other allergic conditions appear to be on the increase especially in children with estimates of between 10-15% of children suffering with asthma1. Numbers increase as countries become more westernized. No single factor has yet been identified to explain this altered immune response and it will probably involve a combination of factors including family susceptibility.

It is generally accepted that early colonisation of gut bacteria is crucial for the development of a healthy immune system so babies can build up tolerance to dietary and environmental factors 2. The early colonisation of the baby’s gut happens during the natural birthing process as the baby makes contact with its mother’s birth canal and during handling and breast feeding. So the development of the baby’s immune system is influenced by its mother’s own microbial population before and after birth and by its food source. It has been observed that breast fed babies have predominantly Bifidobacteria in their gut which is quite different to those who are bottlefed 3.Also a baby born by C-section can potentially be exposed to different microbes which may increase the child’s risk of developing allergies such as asthma, allergic rhinitis (hayfever) or eczema3,4.

A recently reported Swansea Baby Study investigated the effects of probiotic supplementation on the development of eczema measured at two years of age. It involved both mothers and babies with a family history of eczema who were given the probiotic of ‘friendly gut bacteria’ as a mixture of 10 billion Lactobacilli and Bifidobacteria. The women received the probiotic in the last trimester of pregnancy and the first six months after birth with babies being supplemented every day for the first six months after birth. They found that the babies receiving the probiotics were 57% less likely to develop eczema and 44% less likely to react to common allergens such as pollen, cow’s milk, egg and house dust mite. They concluded that both the strain and dose of probiotic was a key factor 5.

A further study of babies receiving neonatal antibiotic treatment resulted in a greater risk of wheezing which required treatment with a steroid inhaler at 12 months and thought to be related to the bacterial imbalances and overgrowth of resistant organisms 6. Antibiotic use in the first six months of life has also been associated with allergic skin reactions and changes in structure and function of the gut particularly with the absorption of certain vitamins and minerals3. These bacterial imbalances may also result in antibiotic-associated diarrhoea when probiotic supplementation can help balance gut flora and reduce overgrowth of opportunist disease causing organisms7.

These studies demonstrate the need to achieve and preserve the initial colonisation of baby’s gut population of ‘friendly’ microorganisms to minimise the chance of developing allergies. Mothers with a history of family allergies may benefit from gut recolonisation with probiotics before or during pregnancy to ensure they can pass on healthy gut flora to their children.


  1. Yunginger JW et al (1992) A community-based study of the epidemiology of asthma. Incidence rates, 1964-1983. Am Rev Respir Dis 46:888-894
  2. Iannith T & Palmieri B (2010) Therapeutic use of probiotic formulations in clinical practice. Clinical Nutrition 29:701-725
  3. Levy J (2000) The effects of antibiotic use on gastrointestinal function. Am J Gastroenterol. 95(1 Suppl):S8-10.
  4. Björksten et al (1999) The intestinal microflora in allergic Estonian and Swedish 2-yeat old children. Clin Exp Allergy 29(3):342-346
  5. Allen SJ et al (2012) Probiotics and atopic eczema: a double-blind randomised controlled trial. Arch Dis Child 97: S1 A2
  6. Alm B, Erdes L, Möllborg P, Pettersson R, Norvenius SG, Aberg N, Wennergren G (2008) Neonatal antibiotic treatment is a risk factor for early wheezing. Pediatrics 121(4):697-702
  7. Plummer SF et al (2004) Clostridium difficile pilot study: effects of probiotic supplementation on the incidence of C. difficile diarrhoea. International microbiology 7(1): 59.