Like Kids, The Human Microbiome Changes As It Grows Older

A baby’s gut microbiome sets the road map for the immune system, nervous system, and growth and development. Besides bacteria, viruses and fungi also contribute to the microbiome, and a complex dynamic exists. The infant’s microbiome is established early and matures during the first years of life, followed by a relatively stable adult microbiome after 3 years of age.

The first one to three months of life is a critical window to stay healthy and avoid chronic illness for the rest of your life, and the maternal microbial reservoir plays a crucial role in this process. Since maternal gut strains adapt and integrate better in the infant, vaginal delivery, breastfeeding, maternal health, and nutrition transfer good bacteria and help to shape a healthy microbiome. C-section, formula feeding, and antibiotics eliminate bacterial transfer or kill parts of the microbiome and are associated with the risk of infections. Swabbing infants with maternal vaginal fluid at the time of C-section ( also called vaginal seeding), appears to alter the infant’s microbiome towards that of the vaginally-delivered infants, but the procedure has been questioned since the real goal should be transferring the mother’s gut bacteria. These changes in the microbiome can have important life-long consequences. For example, children born via C-section have a greater risk of developing asthma and other allergic diseases.

Koalas get microbiome transfer to their babies (“joeys”) right? The young Koala only drinks its mother’s milk for the first six to seven months and slowly develops in a pouch. At about 22 weeks, its eyes open, and it begins to feed upon a substance called “pap”, or microbiome -a rich form of feces, which the mother produces in addition to milk. The mother’s microbes in pap allow the baby koala to digest eucalyptus leaves, their main food source.

Breastfeeding is also an important factor in establishing a healthy microbiome. Besides good microbes, breast milk contains multiple components that protect the infant against infection, and human milk oligosaccharides act as prebiotics, promoting the growth of good bacteria. Breastfeeding reduces upper and lower respiratory tract infections and gastrointestinal infections in infants. Breastfeeding also reduces the development of eczema and asthma in children and may even avoid obesity and type II diabetes later in life. The microbiome of breastfed infants is a distinct microbial population compared to those who are formula fed, and these differences persist into adulthood.

Recent studies found that the gut microbiota of children continued to develop after the age of 3 years and may be more changed by environmental factors more than that of adults. Diet is a key regulator of microbiome structure and function across the lifespan. As children consume more complex diets, associations between dietary patterns and the microbiota emerge. In children, prebiotics, such as inulin, increase good bifidobacteria and dietary fibers reduce fecal pH and increase alpha diversity and calcium absorption. When exploring associations between the gut microbiome and dozens of early-life factors, researchers found that children’s pre-school diet (including intake of plant-based protein and dietary fiber) and how long they were breastfed as infants correlated with the composition and functional capacity of the gut microbiota at 6 to 9 years of age.

Skin, the largest organ of the body, acts as a physical barrier to prevent the invasion of foreign pathogens while providing microbiota. The harsh dry physical landscape of skin, particularly the nutrient-poor, acidic environment, makes it an inhospitable base for the microbiome. But bacteria are hardy survivors in such a cool, acidic and desiccated environment , and they have adapted to utilize sweat, sebum lipids, and dead cells.

Cooperation between the microbiota, host skin cells, and the immune system is responsible for maintenance of skin health, and a disruption to this delicate balance, such as by pathogen invasion or a breach in the skin barrier, may lead to impaired skin function. However, these changes appear to be temporary and the healthy skin microbiome is naturally resilient. Some skin diseases are associated with an altered microbial state called dysbiosis; reversion of this dysbiosis may help prevent and/or treat acne, eczema and chronic wounds. In teenagers, the skin microbiome is restructured during puberty, when increased hormones stimulate the skin’s glands to produce lots of oily sebum.