The intestinal microbiota has a central role in our health. We already know its unsuspected link with the brain and its impact on neurodegenerative diseases, stress, anxiety. However, the brain is not the only organ with which it works closely. Indeed, there is a new axis: the skin-gut axis. A Canadian research team has been working to prove this.

The researchers observed whether UVB light had an impact on the gut microbiota composition.

A clinical trial to prove the gut-skin axis

A pilot study was conducted between February and April 2018 on 21 women with skin types ranging from I to III (i.e. very fair to light skin) according to the Fitzpatrick classification. Participants were not required to have visited sunny destinations in the 3 months prior to the study start.

Women were randomised according to their response to whether they took vitamin D supplements during the winter period:

  • Those supplemented were asked to report their intake and showed sufficient serum vitamin D levels;
  • Those not supplemented, with insufficient serum vitamin D levels.

The volunteers’ bodies were then exposed to UVB 3 times, with an increasing level of UVB at each visit.

Fecal and blood samples were collected at different times of the trial to observe changes in gut microbiota composition and vitamin D concentrations.

Unequivocal results

In general, blood tests indicated that UVB exposure increased vitamin D levels in all participants.

Stool analyses showed positive qualitative and quantitative changes with UVB in the intestinal microbiota of women who were not supplemented with vitamin D… Until a similar microbial diversity and composition is achieved as in the supplemented women.

Results go further, indicating that certain bacterial genera are correlated with vitamin D rate, such as Lachnospira, Agathobacter, Dorea, Fusicatenibacter…

 

This study shows that there is a link between UVB, the skin and the intestinal microbiota via vitamin D synthesis. Further studies are needed to confirm these results.

LC

References

BOSMAN ES, ALBERT AY, LUI H, DUTZ JP, VALLANCE BA. Skin exposure to narrow band ultraviolet (UVB) light modulates the human intestinal microbiome. Front Microbiol. 2019, 10:2410

Picture: Freepik