We've updated our Privacy Policy to make it clearer how we use your personal data.

We use cookies to provide you with a better experience. You can read our Cookie Policy here.

Advertisement
Sunlight Exposure Is Reflected in Your Poop
News

Sunlight Exposure Is Reflected in Your Poop

Sunlight Exposure Is Reflected in Your Poop
News

Sunlight Exposure Is Reflected in Your Poop

Credit: Pixabay.
Read time:
 

Want a FREE PDF version of This News Story?

Complete the form below and we will email you a PDF version of "Sunlight Exposure Is Reflected in Your Poop"

First Name*
Last Name*
Email Address*
Country*
Company Type*
Job Function*
Would you like to receive further email communication from Technology Networks?

Technology Networks Ltd. needs the contact information you provide to us to contact you about our products and services. You may unsubscribe from these communications at any time. For information on how to unsubscribe, as well as our privacy practices and commitment to protecting your privacy, check out our Privacy Policy

The Sun can indeed shine out of your backside, suggests research. Not because you’re self-absorbed, but because you’ve absorbed gut-altering UV radiation.

This is the first study to show that skin exposure to UVB light alters the gut microbiome in humans. Published in Frontiers in Microbiology, the analysis suggests that vitamin D mediates the change – which could help explain the protective effect of UVB light in inflammatory diseases like MS and IBD.


Ratifying rodent studies


Sun exposure, vitamin D levels and the mix of bacteria in our gut are each associated with risk of inflammatory conditions like MS and IBD. Scientists hypothesize that a causal chain links the three.


Exposure to UVB in sunlight is well-known to drive vitamin D production in the skin, and recent studies suggest that vitamin D alters the human gut microbiome. However, that UVB therefore causes gut microbiome changes, via vitamin D production, has so far been shown only in rodents.


In a new clinical pilot study, researchers tested the effect of skin UVB exposure on the human gut microbiome.


Healthy female volunteers (n=21) were given three one-minute sessions of full-body UVB exposure in a single week. Before and after treatment, stool samples were taken for analysis of gut bacteria – as well as blood samples for vitamin D levels.


Rich as feces


Skin UVB exposure significantly increased gut microbial diversity, but only in subjects who were not taking vitamin D supplements during the (winter) study (n=12).


“Prior to UVB exposure, these women had a less diverse and balanced gut microbiome than those taking regular vitamin D supplements,” reports Prof. Bruce Vallance, who led the University of British Columbia study.  “UVB exposure boosted the richness and evenness of their microbiome to levels indistinguishable from the supplemented group, whose microbiome was not significantly changed.”


The largest effect was an increase in the relative abundance of Lachnospiraceae bacteria after the UVB light exposures.


“Previous studies have linked Lachnospiraceae abundance to host vitamin D status,” adds Vallance. “We too found a correlation with blood vitamin D levels, which increased following UVB exposure.”


This indicates that vitamin D at least partly mediates UVB-induced gut microbiome changes.


The results also showed some agreement with rodent studies using UVB, such as an increase in Firmicutes and decrease in Bacteroidetes in the gut following exposure.


Getting to the bottom of UVB’s protective effect


“In this study we show exciting new data that UVB light is able to modulate the composition of the gut microbiome in humans, putatively through the synthesis of vitamin D,” Vallance sums up.


The study is not designed to show the exact mechanism by which the microbiome changes occur, but both UVB and vitamin D are known to influence the immune system.


“It is likely that exposure to UVB light somehow alters the immune system in the skin initially, then more systemically, which in turn affects how favorable the intestinal environment is for the different bacteria.”


The role of the microbiome in these conditions is also at an early stage of research. However, gut bacteria are known to modulate the immune system, as well as the passage of pathogens and other substances from the blood into the brain.


“Our results identify a novel skin-gut axis that may contribute to the protective role of UVB light exposure in inflammatory diseases like MS and IBD,” concludes Vallance.

Reference
Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome. Else S. Bosman, Arianne Y. Albert, Harvey Lui, Jan P. Dutz and Bruce A. Vallance. Front. Microbiol., 24 October 2019, https://doi.org/10.3389/fmicb.2019.02410.

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.

Advertisement