Feeding Baby. Baby eating milk from the bottle. Mother Feeds HerThe human gastrointestinal tract has been identified as one of the most densely populated part of the body with microbes (known collectively as the gut microbiota). The initial colonization of the gut by microbes begins in utero even before birth and continues during the first years of life. The composition and numbers of neonatal microbiota are influenced by many factors, including mode of delivery (vaginal versus caesarean), method of feeding (breastfeeding versus formula milk), perinatal antibiotic usage, prematurity and the surrounding environment.

The probiotic concept dates back to the 1900s and the Ukrainian-born Nobel Prize winner Elie Metchnikoff, who noticed that consumption of milk products containing bacteria contributed to the long and healthy lives of Bulgarian peasants. Probiotic (from the Greek “for life”) was originally proposed as an alternative to the term antibiotic (“against life”) and has been defined as “live microorganisms which, when administered in adequate amounts, confer health benefits on the host.” Some of the most widely used probiotic organisms include Lactobacillus acidophilus, L. casei, L. paracasei, L. reuteri, L. rhamnosus, Bifidobacterium animalis subspecies lactis, B. bifidum, B. infantis, B. longum and Saccharomyces boulardii.

Probiotic supplementation during the neonatal period can help improve the intestinal immune system and establish a balanced beneficial microbiota that can be maintained despite the challenges posed to factors such as antibiotic therapy, poor diet and infections.

This article will focus on the role of probiotics on allergy and respiratory tract infections during infancy and childhood.

Can probiotics prevent eczema?

In allergic diseases (eczema, rhinitis, asthma), exaggerated reactions occur to normally harmless substances (allergens) found in foods or in the environment. The body’s immune system views the allergen as an invader and its white blood cells produce immunoglobulin E (IgE) antibodies that attach to mast cells in the blood causing the release of potent chemicals such as histamine. These chemicals can induce allergic reactions such as urticarial (hives) – a raised, itchy red rash – swelling of the lips, tongue, eyes and/or face, abdominal pains, vomiting, diarrhea or atopic eczema when the skin becomes dry and cracked.

The incidence of allergic diseases in infants is linked to the allergic status of their parents, being approximately 20-30% in those with allergy in first degree relatives and 10% in the general population. In the United States between 2000 and 2010, the incidence of eczema or any kind of skin allergy increased from 8.6% to 17.1% among non-Hispanic black children, from 5.0% to 9.9% among Hispanic children, and from 7.6% to 12.6% among non-Hispanic white children under 17 years of age. It has also been found that 8% of children in a cohort of 38,480 under-18 year olds had some form of food allergy, corresponding to an estimated 5.9 million children in the United States suffering some form of food allergies.

There is evidence that imbalances in the early gut colonisation are associated with the development of sensitization and allergy, and the hygiene hypothesis suggests that infants in today’s relatively germ-free environments (due to improved hygiene, reduced family size, routine vaccination, frequent antibiotic use and reduced exposure to infections) have become under exposed to the microbial stimuli that are necessary for the maturation of our immune systems during the first years of our life.

Several studies have indicated a role for probiotic supplementation from birth for the prevention of allergy because, as mentioned above, exposure to probiotic bacteria can stimulate the immune system and “train” it to produce an appropriate response to allergens.

One of the first studies with probiotics and allergy was performed with mothers who were at risk of having babies who would develop allergic disorders. A daily dose of 10 billion Lactobacillus rhamnosus GG was given to both the pregnant women (2-4 weeks before expected delivery) and to the mothers or their infants for 6 months postnatally. At 2 years of age, the frequency of eczema was reduced by half among the infants given probiotics compared to those on placebo, and this effect had persisted up to 7 years of age.

In a large U.K. study with 454 mother-infant pairs, a daily dose of 10 billion of the Lab4b probiotic mixture containing a combination of both Lactobacilli and Bifidobacteria was given to pregnant women (from 36 weeks) and directly to their babies during the first six months of life. For infants who were given the probiotics the risk of developing atopic eczema was reduced by 56% and sensitization to common allergens such as cow’s milk or hen’s egg was decreased by 44% compared to those on the placebo.

All of the probiotic clinical studies have been reviewed and it shows it is possible to achieve a 20% reduction in the incidence of eczema and atopic eczema in infants and children receiving probiotics. In fact, the World Allergy Organization guideline panel has recently proposed the use of probiotics for pregnant women, breastfeeding mothers and infants at high risk for allergy because it may be beneficial for the prevention of eczema.

Can Probiotics Prevent Colds?

There is also growing evidence suggesting that probiotics are beneficial in reducing the frequency and duration of upper respiratory tract infections (URTIs), which can be caused by a variety of viruses. The most common symptoms are cough, sore throat, sneezing, runny or blocked nose, headache, pain and elevated temperatures.

Children tend to have a much higher incidence rate of URTIs than adults, averaging 2-9 episodes per year. Symptoms usually persist for between 3-10 days although coughing may persist for several weeks.

The common cold is responsible not only for a large proportion of absenteeism of children from daycare centers and schools but also for the absence of the parents or caregivers from work. According to the Centers for Disease Control and Prevention, 22 million school days are lost annually due to colds in the U.S. with the financial cost running into many billions of dollars.

Painkillers are commonly used for cold-symptom management but antibiotics are only recommended for the bacterial infections; their use for viral infections (such as the common cold) is at best ineffective and can potentially contribute to antibiotic overuse and the development of antibiotic resistance.

The value of the impact of probiotics in the management of common colds was shown recently in a study with preschool children aged 3-6 years receiving a daily dose of 12.5 billion of the Lab4 probiotic mixture containing Lactobacilli and Bifidobacteria with Vitamin C (50mg). The children were given the probiotic daily throughout the winter for a period of 6 months and the incidence of URTI among those receiving the Lab4 probiotic was reduced by 33%. The reduction of infection resulted in a concomitant reduction in the number of days missing from preschool/daycare centers by 30%.

In the latest version of the Cochrane Review, probiotics were found to achieve a 47% reduction in the number of children and adults experiencing episodes of URTIs and the duration of the URTI episodes was reduced by about 1.9 days. Probiotics also contributed to a reduction in both absenteeism from school due to colds and in antibiotic usage.

Conclusion

The establishment of a balanced healthy neonatal gut microbiota and its maintenance through childhood and adulthood should be considered as a strategy to minimise the development of both chronic and acute diseases. As our knowledge of the human microbiome increases through the advances in molecular science techniques, the potential role for probiotics to optimise the establishment and composition of the gastrointestinal microbiota from birth to contribute to our overall wellbeing is becoming more and more evident.

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From issue: 30/03-04