Recent research has unveiled a new factor impacting the diversity of the gut microbiome: the time of day.
Our bodies are home to countless microorganisms, each person harboring a distinct set of microbes. Scientists have identified various factors influencing gut microbiome diversity, including diet, living conditions, exercise, and maternal lineage. Now, researchers at the University of California San Diego have revealed time of day as another significant influencer. This discovery is so pivotal that they are urging the National Institutes of Health (NIH) to mandate researchers to disclose this detail in their publications.
In a recent publication in Nature Metabolism, the researchers observed that the gut microbiome undergoes daily fluctuations leading to distinct microbe populations in the morning versus the evening. This disparity implies that analyzing a stool sample taken during breakfast would yield vastly different findings compared to one taken before dinner. The UC San Diego team suggests that this variability is hindering the replication of gut microbiome studies among researchers.
The lead author of the study, Dr. Amir Zarrinpar, a gastroenterologist and associate professor at UC San Diego School of Medicine, highlighted the impact of timing on microbiome research. He emphasized that the timing of sample collection can significantly alter the presence of microbes, consequently influencing the results and conclusions drawn in studies.
Traditionally, scientists conduct experiments to address specific inquiries and to establish findings that can be replicated by others. In the realm of gut microbiome research, stool samples are collected to identify present microorganisms and their quantities, linking these variations to disease mechanisms.
The study’s team compared computer analyses of prior studies, including their own, revealing that microbiome changes over time can be as influential as dietary factors. Dr. Zarrinpar shared a key insight from the research, highlighting how the microbiome in a mouse can significantly shift within hours after eating breakfast, showcasing the substantial impact of sample collection timing on study outcomes.
Dr. Zarrinpar was motivated to conduct this research after an illuminating conversation with a colleague. They discussed an instance where a postdoctoral researcher was unable to reproduce the findings of their predecessor, later discovering that the discrepancy was linked to the timing of sample collection affecting the prevalent bacteria detected.
Ensuring the reproducibility of experimental results is vital to determining the reliability of new scientific discoveries. Microbiome research is currently grappling with a replicability challenge, driven by the interdisciplinary nature of the field, the complex interactions between microorganisms and their hosts, and the multitude of variables involved.
Addressing these issues, Dr. Zarrinpar believes that incorporating the findings regarding sample timing significance could help ameliorate the replicability crisis in microbiome research. By advocating for standardized guidelines on consistent sample collection times and methods, he aims to foster collaboration among researchers, funding agencies, and journal editors to uphold these standards.
This groundbreaking research received funding from the National Institutes of Health, the Soros Foundation, and the American Hospital Association. Collaborators on the study included researchers from the University of California San Diego and the University of Wisconsin-Madison.
