Microbes : The Gut-Brain-Skin Link

Following up on my previous post in which I wrote of gastrointestinal (GI) microbiota and its role in inflammation, hunger signaling and obesity, I would now like to expand on this area to examine the intricate link between our GI health, our mental and emotional states, as well as the quality of our skin, as influenced by dietary intake.

The gut-brain-skin axis is not a novel hypothesis. As far as 70 years ago, dermatologists John H. Stokes and Donald M. Pilsbury first concluded that emotional and mental distress could upset the delicate balance of microbiota in our digestive tracts, thereby causing inflammation. It was then suggested that bacterial induced inflammation increased GI permeability (what is now known as the "leaky gut"), setting the stage for systemic and local inflammation such as skin problems. 

During that same period, research also showed about 40% of individuals in a study with acne often produced insufficient amounts of stomach acids, which attracted movement of harmful bacteria from the lower GI, i.e. the colon, to the upper parts of the GI, causing an imbalance of beneficial microflora. At the same time, another study found low levels of "good bacteria" in the feces of patients with mental disorders, further substantiating the link between gut and brain health.

Today, this theory is gaining even more momentum as modern day diets wreck havoc in our digestive systems, ruining the natural balance of gut microflora. Consequently, we are seeing rising incidences of gastrointestinal disorders such as bloating, diarrhea, constipation, irritable bowel syndrome, gastric reflux. Through multiple ways, gut health has also been known to cause depression, anxiety, chronic fatigue, as well as skin disorders such as acne vulgaris, rosacea, dermatitis.

According to a recent report published in an issue of Gut Pathogens, underproduction of stomach hydrochloric acid (hypochlorhydria) encourages the growth of bad bacteria, a condition known as small intestinal bacterial overgrowth (SIBO). Manifestations of this condition bear wide-ranging degrees of seriousness, from bloating, diarrhea, constipation, to severe malabsorption (1).

SIBO was also detected in those individuals afflicted with fibromyalgia and chronic fatigue syndrome. Furthermore, SIBO could lead to competition for nutrients from excess bacteria and as a result, cause the malabsorption of macronutrients, B vitamins and other micronutrients. Additionally, SIBO was closely linked to emotional disturbances such as depression and anxiety. It was reported that those who were afflicted with acne rosacea were 10 times more likely to possess conditions of SIBO, when compared with individuals of healthy skin.

Gastrointestinal Permeability, a.k.a. leaky gut, was yet another condition closely associated with acne vulgaris. Bacterial toxins from the gastrointestinal tract were often observed in the blood stream of acne sufferers, strongly suggesting a compromised gastrointestinal tract which allowed such toxic materials to cross the tight junctions lining intestinal walls, over into the circulatory system. Both increased gut permeability as well as irritable bowel syndrome have also been evidenced to associate with depression and anxious behavior. 

According to the report, constipation was considered to be "the rule" in acne sufferers. A longer gut transit time also related positively with depression, which corroborated with an earlier study indicating that bacterial toxins caused depression-like behavior in mice.

Not only have Mental Health patients been reported to posses reduced levels of L.acidophilus, it appeared that the "mental health impairment" scores of mental patients were much higher if they simultaneously possessed conditions of acne vulgaris. Some researchers have also identified a specific group of psychological traits, referring them to what they called "the acne personality" which predicates that anxiety, depression and stress reactivity precedes disease onset of acne vulgaris. Hence, the triangle of influence between our gut-brain-skin can hardly be overstated.

Other observations reflected the direct correlation between increased dietary intake of western "sweet, fried, calorie-rich foods with low nutrient density" with both decreased beneficial microbiota in the gut, together with increased risk of acne. It was also duly noted that incidences of acne were extremely rare in hunter-gatherer communities even though such populations have vastly increased contact with soil organisms. Poor dietary habits such as adoption of the western diet led to the elimination of good bacteria in our digestive systems.

The efficacy of oral Probiotics in attenuating the gut-brain-skin inflammatory processes was also examined in the report. Administration of oral probiotics controlled the release of inflammatory properties in both skin and intestinal tract, and decreased both lesion counts and sebum production.  At the same time, the use of probiotics also increased levels of tryptophan, serotonin, dopamine as well as the production of omega-3 fatty acids in tissue cells, leading to significant improvements in feelings of depression, anger, anxiety as well as lowered cortisol. Application of oral probiotics influenced a peptide known as substance P, which was understood to be the mediator for communication between the gut, brain and skin. 

At this point, I would like to highlight some natural and delicious ways to add "friendly" microorganisms to our guts. In her revealing book Deep Nutrition, the author Dr Catherine Shanahan talked about the many virtues of adding fermented foods to our diets. According to Dr Shanahan, microbes in fermented foods "literally fight for our lives". In our bodies, they act as our defense against pathogens, improving our guts' ability to absorb nutrients. They also neutralize toxins which would otherwise be harmful, and in doing so, they themselves are transformed into nutrient powerhouses for our benefit. Dr Shanahan even mentioned an ancient Egyptian skin treatment using microbe-infused blends of fats as topical application (2).

Of course, this article would not be complete without a big warning on the detrimental effects of sugar consumption on gut microbiota, brain functions, and skin. Indeed, sugar (in ALL forms), is the chow of choice for pathogenic microorganisms. These microbes feasts on sugar, leading to an overgrowth of harmful microflora. Additionally, sugar has been known to be an immunity suppressant, making us susceptible to invading parasites, viruses and bacteria. 

Never mind that it is fine gourmet for germs, turns out that the "icing" on this icky cake also has direct damaging effects on our minds and skin. Sugar messes with the dendrites (branch like arms) on our brain cells and interferes with cell-to-cell communication, leading to Alzheimer's, dementia and learning difficulties.

And to top it all off, sugar glycates with proteins, literally creating a sticky mess in our bodies, causing tissue breakdown all over our bodies i.e. think wrinkly sagging skin, that under chin jowl, foggy brain, creaky joints, stiffening arteries etc. Yes, sugar makes us stupid AND old.

When I speak of avoiding sugar, the common reaction I get is "everything in moderation", as if swinging away to the left or right of some “sugar middle ground” would jeopardize our sensible balanced diets. Well, here’s the thing : First, that phrase is hackneyed, overrated and misused. It would only be meaningful if we applied it to something that is good for us to begin with. As in : Fish is good for us, therefore eat it in moderation. Second, sugar is a surefire way to get bad bugs, bad skin, bad moods (the list is still growing). Therefore, if it is indeed moderately bad bugs, moderately bad skin and moderately bad moods that we want, then I guess a moderate consumption of sugar would be apt! 

One last word, or three. Eat fermented food.

References:

1. Bowe WP, Logan AC. Acne Vulgaris, Probiotics and the Gut-Brain-Skin Axis - back to the future?. Gut Pathogens. 2011 Jan 31;3(1):1.
2. Shanahan Catherine, Shanahan Luke. (2009). Deep Nutrition: Why Your Genes need Traditional Food. Lawai, HI: Big Box Books.