Exploring the relationship between serum 25-hydroxyvitamin D levels and intestinal fungal communities and their metabolites in postmenopausal Chinese women.

Abstract

Background: Research gaps persist in understanding the interactions between serum 25 (OH)D levels, intestinal fungi, and their metabolites in postmenopausal women.

Methods: This study, approved by the Ethics Committee of Zhongshan Hospital, Xiamen University, recruited postmenopausal women from Xiamen. Clinical assessments included Body Mass Index (BMI) calculations and blood tests for various bone-related markers using Roche's electrochemiluminescence system. Bone density was measured via dual-energy X-ray absorptiometry. Fecal DNA was extracted for Internal Transcribed Spacer (ITS) sequencing with a two-stage PCR process and analyzed using high-throughput Illumina sequencing. Metabolites were extracted from fecal samples and analyzed by ultra-high-performance liquid chromatography combined with mass spectrometry. Statistical analyses and data visualization were performed using R, focusing on fungal community structure and correlations with metabolites.

Results: The study analyzed 81 postmenopausal women, categorized into vitamin D deficient (VDD), insufficient (VDI), and sufficient (VDS) groups based on serum 25 (OH)D levels. Other health markers, including age and BMI, were consistent across groups. Notably, Linear discriminant analysis identified distinct fungal communities across VDD, VDI, and VDS groups. In the VDD group, notable fungi included Hanseniaspora occidentalis and Pichia. The VDI group showed enrichment of Candida, while the VDS group had higher abundances Such as Phanerochaete, and Nectriaceae. Alpha diversity metrics, such as the Chao1 index, differed significantly among the groups (p < 0.05). Correlation analysis (Spearman) revealed that fungi like Trichosporon and Penicillium positively associated with 25 (OH)D3, whereas fungi such as Cystofilobasidium were negatively correlated with bone mineral density (BMD). Metabolites like Glutaric acid positively correlated with 25 (OH)D3, while L-Citrulline and Deoxycholic acid were negatively correlated. Additionally, Argininosuccinic acid correlated positively with BMD, whereas Acamprosate and p-Hydroxyphenylacetic acid were negatively associated.

Conclusion: In postmenopausal women, fungal community composition varies significantly with vitamin D status, potentially correlating with serum 25 (OH)D levels and BMD, indicating that specific fungal species may be relevant for therapeutic strategies with osteoporosis and offering insights into the broader bone health effects of vitamin D.