To elucidate the quantification and standardization of cold and hot patterns, the fundamental concepts in traditional Chinese medicine (TCM).

This randomized cross-controlled trial recruited 30 healthy volunteers. Participants in Group 1 underwent 14 days of Coptis chinensis Franch. (C. chinensis, Huang Lian) treatment to shift their body toward the cold pattern, followed by 7 days of washout and 14 days of Cinnamomum cassia Presl (C. cassia, Rou Gui) treatment to shift their body toward the hot pattern. Participants in Group 2 underwent the opposite treatment. Blood and stool samples were collected for routine blood testing and full-length 16S rRNA metagenomic sequencing.

Red blood cells (RBC), hemoglobin (HGB), hematocrit (HCT), and blood platelet count (BPC) were increased by C. chinensis, whereas the mean corpuscular HGB concentration (MCHC) was increased by C. cassia. RBC, HGB, HCT, and BPC were positively associated with the cold pattern but negatively correlated with the hot pattern, whereas MCHC showed opposite relationships. C. chinensis-increased Blautia stercoris was positively correlated with RBC, HGB, and HCT under C. chinensis treatment, whereas C. cassia-enhanced Parabacteroides distasonis_A was positively associated with MCHC under C. cassia treatment. Interestingly, five indicators (RBC, HGB, HCT, Blautia stercoris, and Prevotella copri) had an area under the curve of 0.795 for predicting the cold pattern. Although three indicators (MCHC, Akkermansia sp004167605, and Parabacteroides distasonis_A) showed poor predictive ability for the hot pattern, when the individual’s gut microbiota experienced disturbance by cold Chinese materia medica stimulation, the predictive ability increased to 0.703.

This study suggests that blood parameters and gut microbes may be potential indicators of hot and cold TCM patterns, which could benefit the objectivity and scientific rigor of TCM.