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Clinically trialled probiotic-vitamin C combination supports child immune health

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  • Clinically trialled probiotic-vitamin C combination supports child immune health

Upper respiratory tract infections (URTIs) are common in young children, especially in the winter months.[1] The average child experiences around five URTIs every year; however, more than 10% of children will have 10 or more per year.[2] This is especially evident in those attending preschool, with an incidence level of three times more than stay at home kids, and potential for earlier exposure to their first infectious disease.[3,4

Aside from the stress of caring for a sick child, the societal effects include higher health care costs, increased medication usage, and potential loss of work time for carers or parents.[4] But there are also indirect health ramifications, with the parents being susceptible to catching URTIs more than once in every three times the child is sick, leading to further work absenteeism and potential financial burden.[1] Therefore, alternative strategies may be required to reduce the incidences of coughs and colds in children, which may also alleviate the resulting health and societal effects.[3]

Evidence in children shows that vitamin C has a beneficial effect on the duration of respiratory tract infections, while probiotics may prevent incidences and reduce length of illness. However, the research in using both probiotic and vitamin C together in preschool children had been lacking, until 2015, when the ProChild Study was published.[3]

In the ProChild Study, a randomised, double-blind, placebo-controlled pilot study, the efficacy of a probiotic formulation, called Lab4, combined with vitamin C was tested to determine efficacy in preventing respiratory tract infections (RTIs) in preschool aged children.[3]

For six months, 57 preschool attending children, aged three to six years, received the Lab4 probiotic containing 12.5 billion colony forming units (CFUs) of Lactobacillus acidophilus CUL21, Lactobacillus acidophilus CUL60, Bifidobacterium bifidum CUL20, and Bifidobacterium animalis subsp. lactis CUL34, combined with 50mg of vitamin C or a placebo daily.[3] The primary study measures were the incidence and duration of RTIs, absence from preschool and the number of paediatric visits due to respiratory infection.[3]

The results showed the probiotic and vitamin C combination to be effective in not only preventing URTIs but also in reducing illness duration, absenteeism, GP visits and medication use.[3]

Compared to placebo, the children in the treatment group had:

  • 49% reduced duration of cough and cold symptoms
  • 33% reduced URTI incidence
  • 30% reduced absenteeism from school
  • 43% reduced GP visits
  • significantly reduced use of URTI medications, including antibiotics.[3,5]

This study showed that the combination of the Lab4 probiotic strains with vitamin C is a simple and potentially effective strategy to reduce the incidence and duration of URTIs in preschool children and may help to reduce school and workplace absenteeism.


  1. Sacri AS, De Serres G, Quach C, et al. Transmission of acute gastroenteritis and respiratory illness from children to parents. Pediatr Infect Dis J 2014;33(6):583-588. [Abstract]
  2. Long JC, Williams HM, Jani S, et al. Assessing the appropriateness of the management of upper respiratory tract infection in australian children: A population-based sample survey. BMJ Open 2019;9(5):e026915. [Full text]
  3. Garaiova I, Muchova J, Nagyova Z, et al. Probiotics and vitamin C for the prevention of respiratory tract infections in children attending preschool: A randomised controlled pilot study. Eur J Clin Nutr 2015;69(3):373-379. [Full text]
  4. Enserink R, Lugner A, Suijkerbuijk A, et al. Gastrointestinal and respiratory illness in children that do and do not attend child day care centers: A cost-of-illness study. PLoS One 2014;9(8):e104940. [Full text]
  5. The ProChild Study. Lab4® Probiotics, Cultech. [Source]


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Melissa Peterson has been a writer and educator in the health and medical science fields for over 15 years. Naturopathically trained, Melissa also has postgraduate qualifications in literature research and reviewing. Her business, Words On Therapy, provides many services to industry including technical articles, white papers, blogs, SEO content, copywriting and research collation.