TY - JOUR T1 - The Effect of Various Doses of Oral Vitamin D<sub>3</sub> Supplementation on Gut Microbiota in Healthy Adults: A Randomized, Double-blinded, Dose-response Study JF - Anticancer Research JO - Anticancer Res SP - 551 LP - 556 DO - 10.21873/anticanres.13984 VL - 40 IS - 1 AU - NIPITH CHAROENNGAM AU - ARASH SHIRVANI AU - TYLER A. KALAJIAN AU - ANJELI SONG AU - MICHAEL F. HOLICK Y1 - 2020/01/01 UR - http://ar.iiarjournals.org/content/40/1/551.abstract N2 - Background/Aim: To investigate the effects of vitamin D3 supplementation on gut microbiota. Patients and Methods: Twenty adults with vitamin D insufficiency/deficiency [25(OH)D &lt;30 ng/ml] were enrolled and given 600, 4,000 or 10,000 IUs/day of oral vitamin D3. Stool samples were collected at baseline and 8 weeks for identifying gut microbiota using 16S rRNA gene amplification and sequencing. Results: Baseline serum 25(OH)D was associated with increased relative abundance of Akkermansia and decreased relative abundance of Porphyromonas (p&lt;0.05). After the intervention, we observed a dose-dependent increase in relative abundance of Bacteroides with a significant difference between the 600 IUs and the 10,000 IUs groups (p=0.027), and Parabacteroides with a significant difference between the 600 IUs and the 4,000 IUs groups (p=0.039). Conclusion: Increased serum 25(OH)D was associated with increased beneficial bacteria and decreased pathogenic bacteria. A dose-dependent increase in bacteria associated with decreased inflammatory bowel disease activity was observed after vitamin D3 supplementation. ER -