BALANCING ACT

How do thousands of newly discovered viruses living in our gut microbiome impact our health?

New research suggests we should be aiming to balance, not boost, our immune systems.

Viruses are the most numerous biological entities on the planet. In the human gut alone, hundreds of thousands of viruses called bacteriophages are found. These viruses can infect the bacteria that also lives in the gut. The gut microbiome is the community of bacteria, fungi, viruses, and other microorganisms that make their home in the human digestive tract.

While there has been a lot of information shared recently on how imbalances in our gut microbiome can contribute to diseases, relatively little is known about the role our gut bacteria, and the bacteriophages that infect them, play in human health and disease.

To learn more about these bacteriophages, researchers from the Wellcome Trust Sanger Institute analysed over 28,000 gut microbiome samples collected in different parts of the world, and identified over 140,000 viral species living in the human gut, more than half of which have never been seen before. Lead researcher, Dr

Alexandre Almeida, said: “It’s important to remember that not all viruses are harmful, but represent an integral component of the gut ecosystem. Most of the viruses we found have DNA as their genetic material, which is different from the pathogens most people know, such as SARS-CoV-2 or Zika, which are RNA viruses. Secondly, these samples came mainly from healthy individuals who didn’t share any specific diseases. It’s fascinating to see how many unknown species live in our gut, and to try and unravel the link between them and human health.”

Among the tens of thousands of viruses discovered, a new highly prevalent clade – a group of viruses believed to have a common ancestor – was identified, which the authors refer to as the Gubaphage. This was found to be the second most prevalent virus clade in the human gut, after the crAssphage, which was discovered in 2014. The results of the study form the basis of the Gut Phage Database (GPD), a highly curated database containing 142,809 non-redundant phage genomes. Dr Trevor Lawley, senior author of the study said: “Bacteriophage research is currently experiencing a renaissance. This high-quality, large-scale catalogue of human gut viruses comes at the right time to serve as a blueprint to guide ecological and evolutionary analysis in future virome studies.”

Want to improve the health of your gut microbiome? Research published in The Journal of Nutrition shows that dietary fibre acts as a food source for the good gut microbiota, helping the bacteria to break down complex foods and provide nutrients. Vegetables, fruits, whole grains, nuts and legumes are important plant sources of dietary fibre and eating a variety of these foods helps promote a diverse gut microbiota.