Prebiotics and Probiotics
What are probiotics?
A probiotic is an oral supplement or food product that contains a sufficient number of viable mircoorganisms to alter the microflora of the host and has the potential for beneficial health effects. The main probiotics found in breast milk belong to the species of Lactobacillus and Bifidobacterium.
What are prebiotics?
Prebiotics are mainly oligosaccharides which are non-digestible ingredients that benefit the host by selectively stimulating the growth of the beneficial bacteria in the colon. Approximately 8% of carbohydrates in breast milk are oligosaccharides. Human breastmilk contains over 200 different oligosaccharides.
Pre- and Probiotics in Breast Milk
Breast-fed infants’ gut has a much heavier colonisation of ‘good bacteria’ than formula fed infants which compete with the pathogenic bacteria and protect the infants against viral and bacterial infection in early life such as gastroenteritis and respiratory tract infections. Preterm infants fed with breast milk have significantly lower risk of necrotising enterocolitis. The gut microflora also interacts with the intestinal epithelial cells and promotes the development of an adaptive immune system which helps in the prevention of atopy.
Addition of Pre- and Probiotics in Artificial Formulas
Various strains of probiotics have been added to artificial formulas (Table 1) but studies have yielded contradictory results on their clinical effects in the prevention of gastrointestinal and respiratory tract infection, constipation and colic. This is related to the different strains and concentration of the probiotics and methodology used in these studies. The immunomodulatory effect of breast milk is likely the result of the dynamic interaction between various bioactive agents and the environment. Thus, addition of just one or a few components at fixed concentration is unlikely to mimic the clinical benefits of breast milk.
Prebiotic oligosaccharides have also been added to mimic the breast milk in stimulating bifidobacteria and lactobacilli growth. A few studies have shown that a mixture of short chain fructo-oligosaccharides and galacto-oligosaccharides to long chain fructo-oligosaccharides can achieve a gut flora similar to that of breast-fed infants and lower the incidence of diarrhoea and respiratory tract infections. A few clinical trials have suggested addition of prebiotics to hypoallergenic formulas reduces incidence of atopic dermatitis. There is also some limited evidence to show that prebiotics supplemented formula can reduce stool pH and lead to increased stool frequency and softer stool. Nevertheless, in February 2010, the European Food Safety Authority (EFSA) found insufficient evidence and refused to support the health claim that prebiotics added to infant formula “naturally strengthen the baby’s immune system” for babies up to 12 months of age.
