Comparing the Western Infant Microbiome to Global Infant Microbiomes: Key Differences Explained

A groundbreaking study has uncovered significant variations in the gut microbiome among infants globally. Notably, Western infants tend to lack specific microbes that are prevalent in infants from other regions. This finding could enhance the development of probiotics tailored for premature babies to help ensure effective colonization with beneficial bacteria.

The first 1,000 days are critical for a child’s microbiome development, impacting immune function, mental health, and long-term disease risk. Historically, our knowledge has been limited to Western populations, but a new global atlas of the infant microbiome is now expanding our understanding.

The research, led by Yang Xiao and researchers at the Wellcome Sanger Institute in South Cambridgeshire, England, identified Bifidobacterium longum as a key player in establishing a stable gut microbiota.

The study analyzed stool samples from the UK, Sweden, the US, and seven countries in South Asia and sub-Saharan Africa, including Bangladesh, Pakistan, Kenya, Malawi, Burkina Faso, Uganda, and Zimbabwe.

The focus was on two variants: B. longum longum and B. longum infantis, which have been the subject of most infant gut microbiome research to date. By integrating this data with previously sequenced genomes, the team discovered that about 70% of infants in African and South Asian countries carried B. longum infantis, while less than 2% of infants in the UK, US, and Sweden exhibited the same by two months of age.

“The infantis strain is fundamentally lacking in Western environments,” notes Xiao.

In stark contrast, around one-third of infants in Western countries are colonized by B. longum longum by two months, compared to fewer than 10% in the other regions studied.

This indicates diverse roles of B. longum longum and B. longum infantis in immune system development and protection against infections, which appear to thrive in different geographical environments.

Diet may play a significant role, as Bifidobacterium helps digest nutrients from breast milk, with its composition influenced by maternal diet. “B. longum longum adapts better to Western diets, while B. longum infantis is optimized for other regional diets,” Xiao explains. Other bacteria, such as Bifidobacterium breve, may also contribute to gut colonization.

This research significantly expands our understanding of gut microbiomes, particularly in underrepresented populations. Lindsay Hall at the University of Birmingham, UK, emphasizes the importance of this advancement.

While probiotics are not usually recommended for full-term infants, they can be beneficial for premature ones, as noted in health guidelines. Combining this research’s insights allows for tailored probiotics based on an infant’s region. For instance, B. longum infantis may be advantageous for infants in Africa and Asia but may not persist in Western infants’ guts as effectively. “Understanding bacterial diversity across regions is crucial for identifying the most beneficial probiotics for infants,” Hall concludes.