While eating prebiotic fiber is generally known to be healthy for the gut, is fiber also healthy for your skin? There’s a lot of research backing the idea of a gut-skin axis. So if there is a link between a healthy gut and healthy skin, does dietary fiber play a role?
According to a recent research paper, the answer may be YES! Though the study is in mice and needs to be confirmed in humans, the authors also discovered how it happens. Specifically, they found that consuming fiber reduced allergen sensitivity AND decreased inflammation in the skin.
But how did this all work, what is it about fiber that improves skin, and are there other ways to get these benefits? Let’s dig in.
What is it about eating fiber that benefits the skin?
Before we dive in to the ways we can use this information to our advantage, let’s briefly discuss how this works. Many of the beneficial effects of prebiotic fiber are due to what our gut microbes do with it.
Though we eat fiber to improve our health, we can’t actually digest or absorb it. So when we eat fiber, it makes its way through our digestive tract and in to our colon fully intact. This is where the magic happens.
Over 90% of our gut microbiome resides in our colon. The microbes there take what we don’t use and break it down to things we can. One major product of microbial metabolism in our colon is butyrate.
Butyrate is a short chain fatty acid that has a number of major beneficial effects on our gut and overall health. First, butyrate is the primary fuel source for the single layer of cells lining the colon.
These cells, called colonocytes, use butyrate for energy, which causes a number of other beneficial effects. In the gut, butyrate
- Increases the thickness of the mucus layer
- Decreases permeability by increasing tight junction proteins
- Enhances motility
- Enhances the antibacterial properties of immune cells
- Decreases oxygen, which increases beneficial anaerobic bacteria
- And more…
These effects of butyrate on the gut have a powerful effect on shaping the gut environment. However, the beneficial effects of butyrate aren’t solely reserved to the gut.
Butyrate also enters the bloodstream and has effects on our metabolism, immune function, oxidative stress, and modulating genetic expression via epigenetic modulation. And it just so happens, butyrate may have a beneficial effect on the skin barrier as well.
How dietary fiber enhances skin health
There are a couple of problems with using mice as a model for human microbiome research. First, the mouse microbiome is different than ours. Second, mice use the same detoxification system that we do, but their phase 1 pathways change things differently than ours.
Phase 1 detoxification, also known as biotransformation, can activate or deactivate foreign molecules such as drugs or microbial metabolites. As a result, drugs of supplements that work in mice may not work in us. Mice phase 1 pathways may activate a drug, but the human pathways may deactivate it.
This combination of a different microbiome AND detoxification pathways impacts what’s going in. Consequently, this could mean humans won’t see the same benefits.
Fortunately, they found a way around this. The researchers fed the mice traceable butyrate to see if the effects were via butyrate or potentially something else. They found that the butyrate went from the gut to the skin in minutes and did some pretty amazing things.
The butyrate went to the skin and enhanced mitochondrial energy metabolism. This strengthened the skin barrier in multiple ways and made them less sensitive to allergic reaction due to dust mite allergy.
This study is further evidence of the importance of the gut-skin axis in producing healthy skin. Consuming dietary fiber enhanced skin barrier functions and decreased the sensitive of mice to dust mite allergen.
Clearly, we require further evidence in humans to see if this happens in people. There is evidence in humans that people with atopic dermatitis have lower buyrate and propionate production. This may be the result of a decrease in the keystone microbiome member Faecalbacterium prausnitzii. F. prausntizii increases the prevalence of short chain fatty acid producers in the gut.
One question you may ask is if dietary butyrate found in things like butter are effective. While it certainly may travel the same pathway as in mice, it’s commonly believed that you cannot reach the same levels of butyrate from dietary butyrate as you can from dietary fiber fermentation in the colon.
Therefore, your best bet is to increase fiber to improve skin health based on these mechanisms. Some microbes ferment dietary amino acids from protein to butyrate. Check out which foods have these amino acids in a blog we have here.
You’ll notice these are mostly from higher fiber plant foods that are less bioavailable than animal proteins. So regardless, eat your high fiber veggies!!!