A blue dye method may be capable of measuring gut transit time and identifying significant associations with microbiome diversity and certain metabolic markers, offering a low-cost option at $1 per participant, according to a recent study.

The study, published in Gut, highlighted the utility of a novel blue dye method for measuring gut transit time and its associations with microbiome composition and cardiometabolic health. This method, implemented as part of the PREDICT 1 trial, evaluated 863 healthy adults across the United Kingdom and United States, providing an inexpensive and scalable alternative to traditional measures.

Gut transit time, defined as the duration from ingestion of blue-colored muffins to the first appearance of blue stool, ranged from under 14 hours (fast) to over 59 hours (slow). Longer transit times were significantly associated with increased microbial diversity and specific taxa, including Akkermansia muciniphila, Bacteroides spp., and Alistipes spp. (false discovery rate-adjusted P < .01). Machine learning models achieved an area under the receiver operating characteristic curve of 0.82 in differentiating between extreme transit classes based on microbial profiles.

Compared with traditional proxies, such as stool consistency and frequency, the blue dye method demonstrated stronger associations with gut microbiome diversity and metabolic pathways, including pyruvate fermentation and methanogenesis. The findings demonstrated the utility of this method in characterizing the gut microbiome's role in health and disease.

The blue dye method, costing approximately $1 per participant, was found to be simple, noninvasive, and suitable for large-scale epidemiologic studies. Future research could explore its application in studying diet-microbiome interactions and potential associations with metabolic health markers, including postprandial glucose and lipid responses and visceral fat accumulation.

Although promising, further validation against established methods, such as radio-opaque markers or scintigraphy, may be necessary. The scalability and affordability of this approach suggested its potential as a tool for microbiome research and applications in precision nutrition.

Full disclosures can be found in the published study.