The foundations for health are established early in life and the development of our gut bacteria is a good example.
We have known for around a century that humans have a remarkably large and also extremely diverse microbial ecosystem, which includes bacteria, viruses and fungi. We also know that the marker of a healthy gut bacteria population (called microbiota) is one with a diverse mix of gut bacteria, as well as the right balance between the ‘good’ and ‘bad’ gut bugs. Still, scientists are only now starting to understand and appreciate the many roles these organisms play in our health and development. But few would disagree that a healthy gut bacteria population is important to health across the lifespan, with beneficial nutritional, immunological, and developmental effects reported.
In adults, the human gut supports squillions of bacteria – yep, that’s a lot and even more than the number of cells that make up the human body. In fact, the gut microbiota is considered a big ‘organ’ of sorts in our bodies, able to engage in complex functions and also to produce many by-products or compounds that have various functions in human biology.
Each adult’s gut bacteria profile appears to be unique to each person, and seems to be relatively stable from month to month, but will change from time to time, depending on environmental factors, use of things like antibiotics and the influence of food intake.
It is widely reported that an infant’s gut is essentially sterile (i.e. germ free) until he or she is born, although some scientists have begun to question this idea and suggest that an infant’s gut bacteria may be seeded in his or her mother’s womb. While this hypothesis requires further research, the commonly reported understanding is that the first exposure a baby has to bacteria is when he or she passes through a woman’s birth canal or comes into contact with the outside world for the first time.
Within a few days, bacteria ‘immigrants’ establish a thriving community in an infant’s gut and soon their numbers exceed that of a baby’s own cells. Lots of changes occur in the gut bacteria profiles during the first year of life, but by around 12 months of age, our babies appear to have a gut microbial population which broadly resembles that of an adult.
Simplistically, many studies report that the gut of infants become progressively more dominated by bacteria of the Bifidobacterium and Lactobacillus genera during the early months of life (1-3), which shift towards adult-like gut bacteria profiles to include Bacteroides and others bacteria by the end of the first year of life (1). The realities are much more complex than this: for instance, the actual timing of these developments is varied between babies and differences are observed both within and between breastfed and formula fed babies (1, 2).
So, it seems that the development of the gut microbiota in infants varies from baby to baby and from month to month, but these differences exist within broad common patterns seen in infants as a whole (1).
Various factors influence a baby’s gut bacteria population development. However, like so much in this field of gut microbiota scientific discovery, a lot more research is needed before we really know what is going on…
In the meantime, scientists think that the following factors may influence a baby’s gut bacteria profiles, because of differences observed between groups of infants:
1) caesarian compared with vaginal delivery; and
2) premature versus term gestational age. Incidental environmental exposures may also play a big part in determining each baby’s unique gut bacteria community, including things like exposure to mum, dad and the family’s bacteria communities (e.g. is there a household pet?) and early nutrition exposures, such as breastfeeding, formula feeding or both and the composition and transition to a more grown-up diet.
While there is still a lot to learn about the origins and the development of an infant’s gut microbiota, and the influences on health and disease, we do know that early life nutrition and the environment are important influencers of gut bacteria development.
So for now, it’s all about setting up a diverse and healthy gut microbial ecosystem during the early, to set our little ones up for life. Achieving this early in life is key to achieving optimal long term health.
Prebiotics are defined as selectively fermented ingredients that result in positive changes in the composition and/or the activity of the gut microbiota, and by doing so, provide health benefits.
Essentially, prebiotics are non-digestible carbohydrate fibres like galacto-oligosaccharides, which provide food for the good bacteria in the gut. They do this by passing through the small intestine into the large intestine where most of the gut bacteria reside, where these prebiotic fibre-like materials feed the gut bugs. This allows the good gut bacteria to thrive, which stimulates their growth and allows them to reproduce. These good gut bugs then produce various by products, which have knock-on health benefits and help to improve the ratio between good versus bad bacteria. They also help infants to keep regular with softer stools, helping to keep baby regular (4). This may be because galacto-oligosaccharides increase levels of good gut bugs like bifidobacterium (5).
Human breast milk also contains many complex prebiotics, called human milk oligosaccharides (HMO), which make up around one third of the composition of breast milk. These HMOs have been shown to have important health effects on the developing baby, including benefits to the developing infant’s immune system and gut bacteria. The Bifidobacterium and Lactobacillus bacteria that make up the majority of an infant’s gut bacteria populations during the first year of a life grow robustly on human milk oligosachharides (6).
The science and research on the composition of human breast milk and the importance of human milk oligosaccharides highlights the value of prebiotic oligosacchardies during early life nutrition, particularly if this is considered in the context of the current hypothesis on the role of the gut microbiota in development and wellbeing (4).
Probiotics are defined as live microorganisms that, when administered in adequate amounts, provide some health benefit to the person who takes them (7). Essentially, they are living, healthy bacteria which help to create a healthy gut bacteria profile, if a person’s own gut bacteria profile needs a bit of pepping up.
Like breast milk and prebiotics, breast milk also contains a fertile array of its own probiotics (8). It appears that mum passes these probiotics on to her baby during feeding.
In babies, supplementation with the probiotic called Bifidobacterium lactis Bb12 has been shown to significantly reduce the number of episodes of gastrointestinal infections relative to not having the probiotics (9).
Synbiotics are products that contain both probiotics and prebiotics, which creates a synergy between the two, hence the name synbiotic. An example of a synbiotic food for a baby of around 8-12 months is a little probiotic yoghurt, with a little Freedom Foods Barley+ Porridge – yum!!