Probiotics are microorganisms that are believed to provide health benefits when consumed. The term probiotic is currently used to name ingested microorganisms associated with beneficial effects to humans and animals. Probiotics are popularized in the lay literature for many different clinical problems. They have been studied in infants and children as a preventive or treatment for a variety of infections. Studies on the medical benefits of probiotics have yet to reveal a cause-effect relationship, and their medical effectiveness has yet to be conclusively proven for most of the studies conducted thus far. The putative benefit of probiotics in the prevention of infection relates to potential benefits to the innate and adaptive immune systems of infants.

The goals of this investigation are to study immune system cell function and microbiome in children who are taking probiotics.

To accomplish this goal, we propose a pilot study for which we will obtain blood and nasopharyngeal and stool samples prior to and post probiotic use in children greater than 12 months-36 months over a 27-38 day period

Inclusion Criteria

• Healthy children greater than 12 months-36 months of age
• English speaking parent
• Child has not received a live vaccine such as MMR or Varicella in the past 2 weeks

Exclusion Criteria

• Asthma/allergic rhinitis
• Premature birth (< 36 weeks gestation)
• Known to be lactose intolerant
• Immunodeficiency or any underlying problem requiring the use of steroids or other immunosuppressive agents
• Use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen in the last 2 weeks
• Currently taking probiotics, have received probiotics in the previous two weeks or are unwilling to refrain from the use of non-study probiotics during the next 30 days
• Any antibiotic treatment in the last 2 weeks
• Conditions which might interfere with dispersion of the probiotic after oral administration such as short gut or anomalies of the digestive tract
• Concurrently participating in another clinical study, in which the child has been or will be exposed to an investigational or a non-investigational product (pharmaceutical product or device).