Seasonal variations in circulating endocannabinoidome mediators and gut microbiota composition in humansOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked whether the seasons change the gut microbiome and the circulating endocannabinoidome together in humans. The endocannabinoidome is a network of fat-derived signaling molecules tied to inflammation and metabolism. Researchers sampled the same people at the end of winter and the end of summer. They measured fecal bacteria by 16S rRNA sequencing and plasma lipid mediators by mass spectrometry, while tracking diet, activity, and vitamin D.
Who was studied?
The cohort was 48 adults living in Quebec City, Canada, at latitude 46.8 degrees north. This city swings from about minus 18 degrees Celsius in winter to 25 degrees Celsius in summer. Participants gave plasma and fecal samples at both a winter and a summer visit, roughly six months apart. People with recent antibiotic use, enteropathies, pregnancy, or heavy alcohol or cannabis use were excluded. All were relatively healthy adults in an industrialized setting.
What were the most important findings?
Most circulating N-acylethanolamine mediators dropped in summer versus winter, including PEA, LEA, EPEA, and DHEA. The endocannabinoid AEA did not fall, and among the 2-monoacylglycerols only 2-PG rose. Gut bacterial composition also shifted, with some families decreasing and others increasing in summer. The size of the microbiome shift tracked the size of the mediator shift. These changes were not explained by adiposity, dietary intake, physical activity, or vitamin D status.
What are the greatest implications of this study?
The findings argue that season is a real confounder in studies of the gut microbiome and lipid signaling. Trials measuring these systems may need to account for the time of year. Because vitamin D and lifestyle did not explain the changes, other seasonal cues such as temperature or time indoors may drive them. This is one cohort sampled over a single year, so recurrence and causation remain unproven. The associations are correlational.