RT Journal Article SR Electronic T1 The Effect of Various Doses of Oral Vitamin D3 Supplementation on Gut Microbiota in Healthy Adults: A Randomized, Double-blinded, Dose-response Study JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 551 OP 556 DO 10.21873/anticanres.13984 VO 40 IS 1 A1 CHAROENNGAM, NIPITH A1 SHIRVANI, ARASH A1 KALAJIAN, TYLER A. A1 SONG, ANJELI A1 HOLICK, MICHAEL F. YR 2020 UL http://ar.iiarjournals.org/content/40/1/551.abstract AB 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 <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<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.