The development of the microbiome from infancy to childhood is dependent on numerous factors such as mode of delivery, mode of feeding, fatty acid consumption of breast milk, type or consumption of infant formula, weaning, type of solid food, siblings, pets, hygiene, probiotics, and antibiotics.
According to a study published two days ago in Nature, researchers demonstrated the importance of the diet during infancy and its effect on long term gut health. There have been no studies performed on the extensive characterization of the microbiome in early life.
In this study, 12,500 stool samples from 903 children from 3 to 46 months of age were analyzed from three European countries (Germany, Sweden and Finland) and three US states (Colorado, Georgia and Washington) as part of The Environmental Determinants of Diabetes in the Young (TEDDY) study.
The researchers demonstrated that the gut microbiome goes through 3 distinct phases: a developmental phase (3–14 months), a transitional phase (15–30 months), and a stable phase (31–46 months).
As a result, breastfeeding was the most significant factor associated with the microbiome structure. It was associated with higher levels of Bifidobacterium species and the cessation of breast milk resulted in faster maturation of the gut microbiome. Once infants were weaned, there was a rapid turnover in the microbiome and a loss of most of the Bifidobacterium, replaced by bacteria within the Firmicutes phyla. Firmicutes are typical of an adult microbiome and the appearance of these bacteria occurred much quicker than experts expected once breastfeeding was stopped. Probiotic powders should be considered containing Bifidobacterium when breast milk is not available.
In addition, the type of birth was significantly associated with the microbiome during the developmental phase. Higher levels of Bacteroides species were seen in infants delivered vaginally. The presence of Bacteroides is associated with increased gut diversity and faster maturation.
In a sister paper also published in Nature, researchers analyzed approximately 11,000 stool samples from 783 infants in the TEDDY study to characterize the early gut microbiome in children progressing to type 1 diabetes. They identified that the microbiomes of infants without type 1 diabetes have more genes related to fermentation and short-chain fatty-acid synthesis, which are associated with a protective effect.
I have shared a previous study published earlier this year in PLOS Medicine in which researchers demonstrated how diet during pregnancy and infancy contributes to atopic disease in infants. This was one of the largest ever research reviews assessing over 400 studies involving 1.5 million people.
Another study in Nature Medicine from September 2016 demonstrated the link between the gut microbiome of 1 month old infants and an increased risk of allergies later in life.
There was also a study in March 2015 published in Psychoneuroendocrinology that demonstrated women who experience stress during pregnancy are more likely to have babies with a dysbiosis with a higher incidence of gastrointestinal issues and allergic reactions.
Environmental factors including geographical location and exposures from siblings and pets affect differences in the microbiome. The first few years of life are important for the development of the microbiome. Everyone is born with very few microbes and microbial communities assemble in the body through the first few years of life.