Effect of Vitamin D Supplementation on Faecal Microbiota: A Randomised Clinical Trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 31783602 · doi:10.3390/nu11122888
What was done
In an ancillary double-blind randomized controlled trial conducted between 2014 and 2016, 26 vitamin D-deficient (25-hydroxyvitamin D ≤ 50 nmol/L), overweight or obese (BMI ≥ 25 kg/m²) otherwise healthy adults received either cholecalciferol (a 100,000 IU loading dose followed by 4,000 IU daily) or matching placebo for 16 weeks. Stool samples were collected at baseline and 16 weeks, and faecal microbiota were analysed using 16S rRNA sequencing (V6–V8 region).
What was found
Microbiome α-diversity showed no significant difference between the vitamin D and placebo groups at baseline or follow-up (all p > 0.05), and no clustering by treatment was observed at follow-up (p = 0.3). However, community composition was significantly associated with vitamin D supplementation at the genus level (p = 0.04). The vitamin D group had a higher abundance of the genus Lachnospira and lower abundance of Blautia (linear discriminant analysis score > 3.0). Furthermore, individuals with 25(OH)D > 75 nmol/L had higher Coprococcus abundance and lower Ruminococcus abundance compared to those with 25(OH)D < 50 nmol/L.
Why it matters
This study provides randomized human evidence that correcting vitamin D deficiency selectively alters specific bacterial genera in the gut without disrupting overall microbial diversity.
Limits
The sample size was very small (n = 26), limiting statistical power and generalizability. The cohort was restricted to overweight or obese adults with baseline vitamin D deficiency. Dietary intake, functional metagenomic changes, and clinical health outcomes were not evaluated.
Cited by
- supports Administering vitamin D changes the bacterial composition of human stool.