Introduction: Epithelial Layers
Epithelial cells are a special kind of animal tissue which form sheets of protective or boundary layers between different parts of the body or between the body and the outside world. These sheets are just a few cells thick (just one layer of cells in some cases), in which the cells are squeezed tightly together like paving stones.
Examples of where epithelial layers occur include in the skin, the gut lining, the blood brain barrier (BBB), the mouth and nasal cavities, the retina, the lungs, genitals and kidneys, and many more places throughout the body. As in the skin, their purposes include:
- protection, acting as a barrier to prevent pathogens, toxins and infections getting in or through;
- secretion of liquids, including enzymes and moistening fluids;
- sensing of the environment, including detecting chemicals and temperature changes;
- the absorption of nutrients and transporting them through the linings, thus being vital in nutrient exchanges between different parts of the body.
Just like the skin, these layers can malfunction, be broken through abrasion or damage, become diseased or infected, become inflammed, ulcerated or cancerous or dry out due to dehydration. Importantly, just like the skin, these layers need the right nutritional support (dietary intake) to maintain their health, and thus the right foods are vital for keeping them operating properly.
As we can readily glean from the visible problems which commonly occur with our skin, when such layers do malfunction or become unhealthy, they may:
- stop operating properly as a barrier, allowing the infective agents, which they are meant to stop, through;
- become a source of inflammation (redness) and hence cause immune responses;
- cease absorbing or transporting nutrients properly;
- dry up.
Malfunctioning epithelial linings can also leak blood and other substances from the inside out too. For example, Capillaritis (inflammation of the small blood vessels just under the skin) is a highly visible leaking of blood cells and iron through the skin, which appears as rusty brown patches, often on the shins.
That diseases of these linings are very real is easily demonstrated via the example of Cystic Fibrosis, which is a malfunction principally of the epithelial cells in the lungs, but also tends to affect the nasal cavities and the linings of the digestive systems too. That problems with epithial linings make us prone to infection and invaders is readily highlighted by this extract from the Wikipedia article on this disease:
"The lungs of individuals with cystic fibrosis are colonized and infected by bacteria from an early age. These bacteria, which often spread among individuals with CF, thrive in the altered mucus, which collects in the small airways of the lungs. This mucus leads to the formation of bacterial microenvironments known as biofilms that are difficult for immune cells and antibiotics to penetrate. Viscous secretions and persistent respiratory infections repeatedly damage the lung by gradually remodeling the airways, which makes infection even more difficult to eradicate. Over time, both the types of bacteria and their individual characteristics change in individuals with CF"
The Role of Epithelial Layers in Neurogical Disorders
When epithelial layers are compromised, and the protective functions of these cellular linings are damaged, this can have significant impact on people who already have compromised systems due to chronic illnesses such as Parkinson's, Alzheimer's and MS. In fact, damaged epithelial layers, especially the blood brain barrier (BBB), are becoming increasingly implicated in these diseases as contributing to the causal mechanisms:
"Many neurodegenerative diseases include pathologies due to build up of specific proteins, as in Parkinson's. These proteins are also detectable in increasing amounts in the blood of people with these conditions, particularly in Parkinson's. The extent to which and the mechanisms by which these proteins can penetrate the BBB is currently unknown, yet it is also proven they build up in our brains too, seriously aggrevating the condition."
Toxic metals, iron in particular, have also been found in excessive levels in the brains of people with conditions like PD. People with PD also may have unusually elevated amounts of hormones such as histamine in their brains:
It is possible that a form of Capillaritis, mentioned above, where inflamed small blood vessels adjacent to epithelial layers like the skin start to leak blood and iron, creating rusty brown staining, could be a potential route for unwanted substances to leach through the BBB into the brain too.
Candida infections, which have also been found to be very common in people with neurological diseases, can migrate to the brain through a compromised blood brain barrier, where the fungal infection can cause brain damage such as abcesses, as we explored in
"Candida Albicans is the most common type of yeast infection found in the mouth, intestinal tract... if the immune system is not functioning properly, the candida infection can migrate to other areas of the body, including the blood and membranes around the heart or brain."
An example of a virus infecting the brain is Herpes Simplex Encephalitis (HSE), presumably gaining entry due to a compromised BBB too:
"a neurological disorder characterized by inflammation of the brain (encephalitis). Common symptoms include headaches, fevers, drowsiness, hyperactivity, and/or general weakness. The disorder may have some symptoms similar to those associated with meningitis, such as a stiff neck, altered reflexes, confusion, and/or speech abnormalities."
Herpes has been strongly implicated in diseases like Parkinson's for some time.
Leaking Blood Brain Barrier?
Given the implications of a leaky blood brain barrier (BBB) outlined above, we may ask why we haven't heard about it before, let alone been educated in how to ensure our good BBB health. Indeed, given the large amounts of money we spend on skin health/skincare products these days, it is ironic that we pay so very little attention to this, perhaps even more important, "inner skin" which surrounds and protects our brains. I believe this is partly because it is invisible to us, but more importantly few in the medical establishment have actually bothered to make the connections which I am drawing together in this article, likely due to the ultra-specialized [compartmentalized] nature of our current healthcare professions, which typical results in ingrained, myopic and dogmatic mind sets. In particular, I believe the potential outward signs and symptoms of poor BBB health have been largely ignored. Nevertheless, I hope that this article will give others an impetus to consider their brain health more seriously, and to take a precautionary approach, especially for those of us who are already chronically ill with diseases like Parkinson's, Alzheimer's and MS.
Potential Warning Signs of a Leaky BBB
So how can we improve our awareness of our BBB health when we cannot directly observe or measure it? There are some obvious signs to look out for, such as brain fog, deteriorating memory, mood changes. However, since the BBB involves the same tissue type (epithelial cells) as many other protective barrier linings of the body, it may be worthwhile learning from the case of Cystic Fibrosis. As discussed above, people with CF are prone to problems occurring in not just one, but multiple epithelial layers in their bodily systems. Thus health issues with any one of these barriers may, more generally, infer problems with others too. From this perspective, the monitoring our outer skin problems, especially for dryness, inflammation and obvious infections, but also for conditions like Capillaritis, may alert us to the possibility that we may have a compromised BBB too. Determining the root causes of skin issues and addressing these could therefore be an important step in maintaing brain health. Thus the approach I am recommending here is simply about erring on the side of caution.
Awareness of our digestive tract health is also vital from this perspective, because many diseases which are now associated with a leaky epithelial layer in the gut are also correlating strongly with those in which BBB leaching is now being implicated, including Parkinson's Disease. Constipation, indigestion, stomach ulcers are all therefore warning signs we should take note of too. For example, if we need to wipe our bottom quite a lot after going to the bathroom, this is a sure sign the mucous membrane of our gut lining is not working properly, and for the benefit of the doubt we perhaps should work under the assumption that our BBB is likely to be dehydrated too. Fixing leaky gut is a therefore a wise or common sense precautionary measure.
Other places where epithelial cells also play important protective roles include the nasal cavities, the mouth lining, the lungs, the retina. Dry or stuffy nose, persistent mouth breathing, dry mouth, trouble swallowing, trouble breathing or shallow breathing, dry or bloodshot eyes should therefore all be taken as potential warning signs that something is systematically amiss with our "inner" skins too.
I'm sure people affected by Parkinson's Disease and other chronic illnesses will readily identify that they already have many of these warning sign symptoms that I've listed above. I do not believe this co-incidental.
Blood Brain Barrier Health Care
So what proactive steps can we take to protect our blood brain barrier (BBB) health, aided by carefully observing the states of other epithelial cell layers in our body? One of the most important indicators is the usual suspect - dehydration, because dehydrated membranes, like dry skin, simply do not work properly and are prone to infection. Indeed, dry skin, constipation, stuffy or blocked nose, dry mouth or unusual saliva consistency are all warning signs of chronic dehydration of our epithelial tissues.
Secondly, an anti-inflammatory nutritional regime will be vital, as elimination of problem foods is likely to be crucial for maintaining BBB health too. We should be observant of any food reactions by monitoring our skin response: seborrheic dermatitis, rosacea and dandruff are some of the more obvious outcomes of food based triggers. Likewise, foods which inflame our gut linings, causing stomach upsets, acid reflux and indigestion, also need to be eliminated, as well as those which cause sneezing or rhinitis or which leave a bad taste in our mouth too. Breathing and eye problems, too, may be indicators something is a miss with our protective membranes. One way to address both inflammation and dehydration simultaneously is discussed in
Thirdly, as for what we put in our bodies, what we put on our bodies counts hugely too - skin care, deodorants, hair and oral hygiene products. Careful observation of possible negative effects and their elimination may help to reduce inflammatory or auto-immune attacks on the BBB too.
It may be worth getting tested for allergies and viral, bacterial or fungal infections as well, and addressing these, given the known roles of invaders like Candida and Herpes, which, as described above, can reach the brain.
Positive steps include consuming skin and mucous membrane friendly foods and supplements. Of particular note is the importance of collagen for protective mucous membranes. Many people recommend bone broth in this regard. Gelatine also supports membrane health, and I recommend David Spry's red berry jelly recipe, or variants thereof, which many people with and without Parkinson's Disease have reported quick noticeable benefits from, in terms of digestive and nasal cavity health. Biotin may also be a worthwhile supplement for BBB health too.
For further ways to increase blood brain barrier health, I recommend the article: