Gut bacterial balance affects many different areas of health, but one of the most important to consider is the establishment of healthy gut bacterial balance during infancy. This is a topic Brenda Watson and I have covered many times. Brenda has blogged on this topic a few times, and we cover it in our bookThe Road to Perfect Health.
Healthy gut balance during early life is associated with protection against a range of health conditions, most notably the atopic diseases of childhood — asthma, eczema, and allergies.  Gut balance during infancy is dependent on factors such as mode of delivery, diet, and administration of probiotics or antibiotics. This early gut microbial development primes immune function that can have life-long effects on health.