Anna Marija Helt, PhD
The intestinal (gut) lining is where we absorb the nutrients we get from our food. Did you also know that the lining of our gut protects us as well? Before anything is absorbed across the lining it is still, technically, outside our body. So the gut lining is an important gate keeper. Just like our skin, our gut lining keeps stuff from getting into our bloodstream that we don’t want there, like pathogenic bacteria, our own normal gut microbes, toxic substances or partially digested food molecules. This is why it is important to nourish our gut lining to keep it tone.
A little biology…The intestines are lined in a single layer of a particular cell type known as “epithelial cells”. They’re hooked together with a collection of proteins that make up “tight junctions”. Having the cells of our gut lining tightly packed together keeps stuff from randomly crossing into the body. Many of our nutrients from digestion are actually absorbed through the cells themselves and spit out the other side where they enter the bloodstream. But some nutrients do, in fact, pass between the cells, through the tight junctions, in a regulated fashion. So the tight junctions need to know when to let things through. This is hard for them to do if they can’t hold on properly.
Some of you might have heard of “Leaky Gut Syndrome”. This holds that looser tight junctions renders the gut more permeable, allowing stuff to cross through that shouldn’t. There is some debate in the medical community as to whether it actually exists as a syndrome, but a quick Medline search shows that there are a lot of scientists out there looking into it.
Diving deeper, why might tight junctions be not tight enough? Well, for some it could be genetic: They’re simply born with looser tight junctions. For others, it may be related to their resident gut microbes…either too many of the wrong ones or too many setting up house where they aren’t supposed to be. Leaky gut aside, toxins and bacteria can irritate the gut lining and the resulting inflammatory response may impact the body well beyond the gut.
That said, a healthy balance of gut microbes is important for maintaining a healthy gut barrier, in part by influencing mucus production along the gut lining. Along with tight junctions, this mucus is part of the barrier. Moreover, bacteria activate as much as 10% of all genes related to gut function in the gut epithelial cells. So, who is there has a big impact on what the gut lining is up to. Beyond the gut, these microbes are actually quite crucial for our health and even for our mood ( but more on this in a future article!).
Back to things that increase gut permeability. Regular use of non-steroidal anti-inflammatory agents (NSAIDS) such as ibuprofen may also damage increase gut permeability, as can various disease-related conditions. A typical Western diet, and beverages such as alcohol, may also contribute to increased gut permeability.
Despite the debate on whether Leaky Gut Syndrome actually exists, symptoms associated with increased gut permeability are being explored with an eye towards improving gut health. Regardless of whether or not the syndrome is real, gut health is clearly important for digestive function and nutrient absorption as well as for optimal health.
Further reading for you geeky types:
Bischoff, S, et al (2014) Intestinal permeability – a new target for disease prevention and therapy. BMC Gastroenterol. 14: 189. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4253991/
Mu, Q, et al (2017) Leaky Gut As a Danger Signal for Autoimmune Diseases. Front Immunol. 8(598). https://www.ncbi.nlm.nih.gov/pubmed/28588585
Sigthorsson, G, et al (1998) Intestinal permeability and inflammation in patients on NSAIDS. Gut. 43(4):506-11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1727292/