Exploiting gut bacteriophages for human health

• We emphasise the complexity and individuality of the phageome, and the link to the health state of the host.
• We highlight the practical applications of bacteriophages in medicine and in the food chain.
• We indicate the future directions for bacteriophage research in human health as biomarkers of the microbiota.
• We propose the use of phages as interventions targeted at the microbiota.

The human gut contains approximately 1015 bacteriophages (the ‘phageome’), probably the richest concentration of biological entities on earth. Mining and exploiting these potential ‘agents of change’ is an attractive prospect. For many years, phages have been used to treat bacterial infections in humans and more recently have been approved to reduce pathogens in the food chain. Phages have also been studied as drug or vaccine delivery vectors to help treat and prevent diseases such as cancer and chronic neurodegenerative conditions. Individual phageomes vary depending on age and health, thus providing a useful biomarker of human health as well as suggesting potential interventions targeted at the gut microbiota.