Microbiome
In your body lives a precious and indispensable part of you called your microbiome. This amazing and vital ‘second brain’ is made up of bacteria, fungi, viruses, protozoa, yeast, and archaea that coexist with you from birth. This exceptional part of us is responsible not only for gut health but also immune regulation as well as brain and overall health through interaction with neurotransmitters. In fact, about 90% of the chemicals that control our moods are made in the gut by our microbiome! A healthy gut gives us healthy bodies and minds and for that, we need a healthy microbiome.
Microbiologists believe that our microbial DNA outnumbers our own mammalian cells by a little more than 1 to 1. You are literally more ‘other’ than you are human - and it’s been that way since we were bacteria ourselves. Throughout evolution, our brains and bodies have always had this amazing level of symbiosis with the world around us. As holobionts, we have never existed without bacteria. It's only now, in the modern age of antibiotics, low fiber diets, plastics, and pesticides that we find ourselves leaning perilously close to shutting down the factory that keeps our cerebellum happy and our bodies healthy.
You want a healthy and diverse microbiome. Scientists have shown that a rich ecosystem in your gut drives overall health and lowers disease risk. The way we support diversity and richness in our microbiota is by feeding them their preferred foods of fiber and polyphenols. When we eat fiber-rich foods, the fiber gets to our lower intestine pretty much intact which is where our bacteria are the most prolific. These bacteria then ferment the fiber particles to break down the cell walls which unlocks ‘hidden’ nutrients including lipids, amino acids, antioxidants, and vitamins that we benefit from. We benefit further from the byproduct of fermentation, short-chain fatty acids (SCFA) which are major immune regulators.
There are three types of SCFA that regulate inflammation and influence hormone secretion in the gut: butyrate, acetate, and propionate. Butyrate feeds colonic cells, kills cancer cells, inhibits inflammation, and helps to regulate your immune system. Low butyrate has been linked specifically with autism but is also found in a myriad of other conditions. SCFA block some effects of chronic psychological stress including that of generational and racial trauma making it all the more important for individuals and communities affected by centuries of institutional racism to have access to fresh, fiber-rich foods.
Abundant SCFA also indirectly regulate blood glucose and induce satiety by interacting with hormones in the gut including ghrelin, the hunger hormone, and leptin, the satiety hormone.1 We obtain nearly all of our SCFA from our microbiome and studies have shown that germ-free mice (those without microbiota) have significantly lower amounts of ghrelin and leptin. This means that they are incapable of knowing when they feel hungry or satiated which can lead to disordered eating patterns. Germ-free mice have also been shown to have increased stress responses. What does this mean for us? Low fiber diets literally add to our stress burden on both a physical and neurochemical level while high fiber diets decrease stress and improve our ability to respond to the stresses we face daily. Fiber makes us physically and emotionally resilient. You want SCFA. A lot. And we get them almost exclusively from our gut microbiome fermenting food for us.
Our microbiomes are seeded, or started, from exposure to vaginal fluids during delivery and fertilized by specific nutrients in breast milk. As infants and children, our exposure to pets, dirt, siblings, foods, and antibiotics will shape our microbiome throughout our lifespan. If certain species of bacteria are lost due to antibiotic use or lack of nutrients in those early years, we don’t regain them later in life. This loss, along with antibiotics, pesticides, some medications, and plastics can cause dysbiosis which tends us towards disease.
When we ingest refined plant foods that lack sufficient fiber such as processed grain or sugars, the simple sugars are immediately absorbed through the small intestine without any interaction with our microbes. This starves our microbes while simultaneously training them to crave more refined foods and ultimately shifts our microbial diversity away from a healthy balance and towards dysbiosis. Unfortunately, the standard western diet is packed with these highly processed foods while also being heavy in animal protein that, without adequate fiber intake, slows colon transit time and increases the risk of colon cancer along with a host of other problems.
My own microbiome was poorly seeded as an infant and starved as a child. I was delivered via c-section so had no exposure to vaginal secretions during birth, ate a low fiber, high sugar diet, and was prescribed penicillin yearly for strep throat (ouch!). Despite having pets and being an active outdoors kiddo, I developed severe seasonal allergies and asthma by late middle school. Later I would develop constipation and upset stomachs, often with pain and bloating as well as severe candida infections. Do I have dysbiosis? You bet. Do I get excited when I think about healing myself? Heck yeah!
When we eat unprocessed plant foods we are directly feeding our microbes and thus helping our entire system. Health starts in the gut and you are the strongest ally your body has. By adding a diverse array of plant foods to your diet, you can alter your microbiome in as little as a few days. How powerful is that?!
References:
1. Hansen NW, Sams A. The Microbiotic Highway to Health-New Perspective on Food Structure, Gut Microbiota, and Host Inflammation. Nutrients. 2018;10(11):1590. Published 2018 Oct 30. doi:10.3390/nu10111590
