Vitamin D deficiency is a global epidemic and has been linked to many autoimmune diseases, including type 1 diabetes, systemic lupus erythematosus, multiple sclerosis, and (inflammatory bowel disease) IBD, with studies finding a higher prevalence of these diseases in those who are deficient in vitamin D.

According to a study just published this month, researchers investigated the impact of high dose vitamin D supplementation on the composition of the gut microbiome adolescent girls.

Previous research has shown an interaction between the gut microbiome with vitamin D. Animal studies has shown vitamin D can change the composition of the gut microbiome. This data suggests vitamin D may play role in modulating the microbiome and a deficiency may lead to inflammation or dysbiosis. Some human data demonstrates vitamin D shifting the microbiome in IBD.

This was an intervention study including 50 healthy teenage females between the ages of 12 and 18. All fifty individuals received vitamin D supplementation at 50,000 IU once a week over a nine-week period. Fasting vitamin D levels were assessed at baseline and the end of the study as well as stool samples were taken. At the start of the study 86% of the participants had a vitamin D deficiency (20 ng/ml or less), 8% had an insuffiency (21-29 ng/ml), and only 6% had normal levels (30 ng/ml or higher). As a result, vitamin D supplementation significantly improved vitamin D status as well as increased levels of Firmicutes and Bifidobacterium. In addition, there was a reduction of Bacteroidetes after supplementation.

There are a few mechanisms in which vitamin D may have this effect. It’s impact on the gut microbiome is most likely from immune modulation and well as anti-inflammatory effects which change the microbiome composition.

Although this study used high weekly dosing of vitamin D, most patients will obtain optimal levels of vitamin D in daily doses between 5,000 IU and 10,000 IUs/day. Research suggests daily dosing is more effective than weekly dosing. It is also essential to use a supplement that combines vitamin K or provide a separate vitamin K supplement. There are intricate relationships between fat-soluble vitamins and it is important take this into account with dosing vitamin D supraphysiologically.

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Tabatabaeozadeh SA, Fazeli M, et al. The effects of high doses of vitamin D on the composition of the gut microbiome of adolescent girls. Clin Nutr ESPEN. 2020 Feb;35:103-108.

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