MICROBIOME VIRUSES RESEARCH
Gut health beyond bacteria: a new frontier in microbiome science
In a new scientific study, we explore the hidden ecosystem inside the gut and why viruses may play a far more important role in the health effects of fasting. Discussing new research from Buchinger Wilhelmi, the article also explains how fasting and lifestyle choices can reset and rebalance the gut ecosystem, and outlines practical, evidence-based steps to support gut health in the New Year.
The invisible ecosystem inside you, and why gut viruses may be the next frontier in health
Gut health has moved firmly into the spotlight, and for good reason. Over the past decade, research has repeatedly shown that the structure and function of the gut influence far more than digestion alone. From immune regulation to mood, brain function, and blood sugar control, the gut plays a central role in human health and disease risk.
Much of this research has focused on the gut microbiome, the vast community of microorganisms that reside primarily in the large intestine. These microbes do not simply coexist with us, they actively interact with our biology. Through the fermentation of dietary fibres, gut bacteria produce a wide range of compounds, including short chain fatty acids and vitamins, that enter the bloodstream and influence inflammation, metabolism, and even brain function.
However, not all bacteria are beneficial. Certain bacterial species can produce compounds that promote inflammation or disrupt the gut barrier lining when they become overly dominant. For this reason, gut health is less about eliminating microbes and more about supporting a balanced, resilient microbial ecosystem, one in which beneficial species can thrive and help keep potentially harmful ones in check.
Beyond bacteria: the overlooked world of gut viruses
While bacteria have dominated microbiome research to date, they are not the only inhabitants of the gut. The intestinal ecosystem also includes fungi, archaea, and viruses. Among these, viruses have remained one of the least explored components, despite being extraordinarily abundant. When most people hear the word “virus”, they think of infectious diseases such as influenza or COVID-19. Yet the vast majority of viruses we encounter are either harmless or play neutral or even beneficial roles. Humans are constantly exposed to viruses from birth onwards, and without them, complex life as we know it would not exist.
In our guts, most viruses are bacteriophages – these are viruses that infect bacteria rather than human cells. These phages can influence which bacterial species grow, how they behave, and how they interact with one another. This viral component of the microbiome is collectively known as the gut virome. Understanding how it behaves, and how it responds to dietary and lifestyle interventions, may help explain why some microbiomes are more resilient and adaptable than others.
Fasting and the gut virome: new insights from emerging research
Until recently, very little was known about how fasting influences the gut virome. A new study conducted at Buchinger Wilhelmi has begun to explore this question by analysing viral changes before, during, and after Buchinger fasting.
During the filming of a French television documentary, the supermodel Adriana Karembeu visited our Überlingen clinic for a fasting stay. Our scientific team used highly advanced methods to analyse her gut microbiome, techniques that are still rarely available outside specialised research groups. At the initiative of our Scientific Director, Dr Robin Mesnage, the analysis also included the viral component. Even though this was a single case, the changes we observed were striking and suggested that fasting may have a meaningful impact on gut viruses, a signal that encouraged us to investigate the question more systematically.
Dr. Franziska Grundler
Using precision sequencing techniques, our scientific team joined efforts with top scientists from the EMBL, Europe’s flagship laboratory for the life sciences, to examine how viruses behave before fasting, at the end of a 10 day fast, and again 1 and 3 months later. This analysis was led by Natalie Falshaw. The results showed that fasting temporarily reorganises the gut viruses. The diversity of gut viruses decreased for a short period, while certain important relationships between viruses and beneficial bacteria became more pronounced. Rather than showing patterns typically associated with gut inflammation or disease, these changes appeared to support a more coordinated and balanced microbial system.
In simple terms, fasting seemed to encourage the gut ecosystem to reorganise itself, much like a natural reset. Some of these changes remained visible for several months after the fast and were associated with improvements in markers related to blood sugar control and overall physical resilience. The findings are currently available as a preprint, which means they have not yet undergone formal peer review. We will continue to follow the research closely and keep you updated.
Taken together, this research reinforces the idea that the gut functions as an interconnected, living system. Supporting gut health is therefore not about targeting one single organism or taking a single supplement, but about creating the right conditions for the whole system to rebalance and function well.
Supporting your gut ecosystem in the New Year
While the science on gut viruses continues to evolve, there is already strong evidence for lifestyle habits that support a diverse and resilient gut microbiome as a whole:
🍛 Nourish your microbes with dietary diversity
Eating a wide range of plant foods provides different types of fibres that feed beneficial bacteria. A practical goal is to include around 30 different fruits, vegetables, legumes, nuts, seeds, and whole grains across the week. Diversity matters more than perfection.
🌾 Prioritise fibre intake
Soluble fibres from fruits, vegetables, oats, and legumes are fermented by gut bacteria into short chain fatty acids, which support the immune system and blood sugar control. Insoluble fibres from whole grains and nuts promote regular bowel movements and satiety. Increase fibre gradually if you are sensitive.
⚖️ Support emotional balance
The gut and brain communicate constantly. Chronic stress can alter gut microbial composition, while practices such as meditation, calm eating environments, and mindful routines have been shown to support microbial balance and immune regulation.
🏃🏽♀️ Move regularly
Physical activity stimulates digestion, supports gut motility, and promotes an anti-inflammatory internal environment. Even gentle, regular movement such as walking or cycling can positively influence gut health.
🛌 Protect your sleep rhythms
Sleep deprivation has been shown to reduce microbial diversity. Consistent sleep routines help support both the gut barrier and microbial stability.
🌱 Be mindful of environmental exposures
Pesticides, smoking, and chronic use of certain medications, including proton pump inhibitors, can disrupt the gut microbiome. Choosing organic foods where possible, reducing chemical exposures, and using medications thoughtfully can help protect microbial balance.
🍵 Consider fasting as a reset, not a shortcut
Intermittent fasting and structured long-term fasting can support microbiome renewal by realigning eating patterns with natural rhythms. Fasting is not about deprivation, but about creating a physiological environment that allows multiple systems, including the gut ecosystem, to recalibrate.
Looking ahead
The gut microbiome is a dynamic and responsive ecosystem shaped by diet, lifestyle, and environment. As research into the gut virome advances, it may help explain why certain interventions, including fasting, have such broad and lasting effects on health.
By caring for this invisible ecosystem through daily choices, we support not only digestion, but the foundations of long-term metabolic, immune, and psychological wellbeing.
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