Oral Presentation The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2017

The effect of vitamin D supplementation on faecal microbiome in vitamin D-deficient, overweight or obese adults: a randomised clinical trial    (#60)

Negar Naderpoor 1 , Aya Mousa 1 , Luisa F Gomez-Arango 2 3 , Helen Barrett 2 3 4 , Marloes Dekker Nitert 2 3 , Barbora de Courten 1
  1. Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
  2. The University of Queensland Centre for Clinical Research, Faculty of Medicine, The university of Queensland, Brisbane, QLD
  3. School of Chemistry and Biomolecular Sciences, The university of Queensland, Brisbane, QLD
  4. Obstetric Medicine, Royal Brisbane and Women's Hospital , Brisbane, QLD

Background: Vitamin D deficiency has been associated with type 2 diabetes and inflammation, and more recently, with dysbiosis. Vitamin D supplementation has been shown to improve gut microbiome and intestinal inflammation in animal studies. It is proposed that vitamin D may exert actions on glucose metabolism and inflammation through the gut microbiome. However, limited human studies have investigated the effect of vitamin D supplementation on the gut microbiome.

Methods: In a double-blind randomised clinical trial, we compared effects of vitamin D supplementation (100,000IU loading dose of cholecalciferol followed by 4000IU daily) versus matching placebo for 16 weeks on faecal microbiome (16S rRNA sequencing;QIIME software) in 26 vitamin D-deficient (25(OH)D<50 nmol/L) overweight or obese, otherwise healthy adults. Data on physical activity, sun exposure, and diet were collected using validated questionnaires.

Results: There were no significant differences in physical activity, sun exposure, and diet (overall energy intake, fibre, protein, carbohydrate, total or saturated fat) between vitamin D and placebo groups at baseline and follow-up (all p>0.05). At baseline, the two groups did not exhibit any significant differences in microbiome profiles (p=0.9) or in diversity (p=0.6). At follow-up, there was no clustering based on vitamin D supplementation (p=0.3), however, there was a significant association between community composition and vitamin D supplementation at the genus level (p=0.04). The vitamin D group had a higher abundance of genus Lachnospira, and lower abundance of genus Blautia (linear discriminate analysis (LDA)>3.0).

Conclusion: Our findings suggest that vitamin D supplementation increases abundance of genus Lachnospira previously linked to decreased inflammation and insulin sensitivity, and decreases the abundance of genus Blautia linked to increased insulin resistance. Vitamin D supplementation may, therefore, have a beneficial impact on the faecal microbiome. Further studies are needed to explore whether improved microbiome following vitamin D supplementation would translate into improved clinical outcomes.