The vast array of microorganisms inhabiting our bodies, collectively referred to as the microbiome, has gained recognition for its potential role in enhancing immunity. Professor Daniel M. Davis, who leads the life sciences department at Imperial College London and authored “Self Defence: A Myth-busting Guide to Immune Health,” notes, “Numerous studies link various types of bacteria within the microbiome to both health and illness across nearly all mental and physical conditions.” However, he emphasizes that much of this research is correlational, and a deeper understanding of how the microbiome impacts health is still needed.

Researchers frequently assess one specific aspect of the microbiome: its diversity. In essence, this refers to the range of different microbial species residing in the gut. “A more diverse microbiome appears to correlate with lower incidences of illness,” Davis explains.

Nevertheless, emerging research indicates that the dynamics within the microbiome may be more nuanced than mere diversity suggests. “Recent findings imply that competition among bacteria is crucial,” Davis states. “When certain groups of bacteria engage in mutual feeding and rapidly reproduce, it can have detrimental effects on health. Conversely, if these bacteria are competing for resources, this competition tends to regulate their populations. A microbiome rich in competing species can help preserve a healthy balance.”

What should laypeople take away from this information? Davis asserts, “The microbiome is indeed significant and plays a role in the immune system’s capacity to combat infections. However, our understanding of what constitutes a ‘healthy’ microbiome is still incomplete. We do not yet know how to effectively alter it to enhance health outcomes. Therefore, it is wise to be skeptical of bold marketing claims.” He advises caution towards products that assert, “this will transform your microbiome and improve its health.” The scientific evidence to support such claims is currently lacking.