The Microbiome & Health: Part I
December 29, 2020
By Julita Baker, PHD
Did you know that you have ten times the amount of bacterial cells than your own human cells in your body?
This collection of microorganisms, including bacteria, fungi, archaea, and protists, whose cells account for 10-fold more than our own cells, are what defines our microbiome.
What if I tell you that you may have a completely different glucose response to a cookie than your friend has, and this high or low response is dependent on the type of microbes YOU have. Would you begin to eat differently?
The bacteria living in our bodies are critical to our wellbeing - interacting with virtually all human cells. They influence many factors, such as the development of our immune system and how much energy we extract from the foods we eat. They make vitamins and minerals for us, they determine how high (or low) our blood glucose is after a meal, and they even decide whether we are happy or sad (10). There is much much more to their contribution, which we will discuss below and in future posts.
But before we get into ALL that encompasses our microbiome and health, let’s start with the beginning. Where do these microbes come from?
The Beginning
Not to gross you out, but your first introduction to any microbes (bacteria) was when your mom pooped on you during birth.
Before birth, we have very little, if any, bacteria in our bodies. But this changes the moment we enter the world. Typically, when a baby is born, its face is pointed down towards its mother’s anal canal (if you’ve ever given birth yourself, you know that pooping during labor is inevitable).
Why would our species, and evolution, in general, instill this introduction of microbes into our physiology? What do microbes do for us? Do they benefit (or hurt) us?
In the next several posts, we’ll discuss WHY you need to care about the microbiome and why optimizing your microbiome should be high on your priority list. This will include the following topics:
What is the microbiome? And why is it important?
What do these microorganisms contribute to health and disease?
What physiological systems do these microbes influence? (Think your glucose balance is solely a result of you eating bread or not? Think again!)
What happens when we create a dysbiosis in our gut bacteria?
And finally, what do we eat, what lifestyle factors can we incorporate, and what factors should we avoid to acquire a healthy microbiome?
The ecosystem of bacteria living in our GI tract plays a primary role in our bodies’ critical physiological and even psychological processes. Given this significance, let’s start with the How, Why, and What of the bugs that live inside us.
Colonization of Microbes
Ok, so now that we know we are initially exposed to our first strains of (poop) bacteria at birth. What’s next?
The next exposure following this initial colonization is through breast milk. But the thing about babies and breast milk is that babies’ digestive systems can’t digest breast milk carbohydrates (compounds called HMOs, or human milk oligosaccharides). The bacteria that are inhabiting their tiny digestive systems are the ones that are actually breaking down those complex carbohydrates and making them usable for fuel.
Fascinating, isn’t it? Why would evolution create this physiological outcome?
This need for us to rely on the bacteria in our gut, to digest a fuel source the mother makes to feed her young, tells us we co-evolved with these bacteria to help us survive.
Research conducted by Dr. David Mills and colleagues from UC Davis found that babies’ gastrointestinal tracts are colonized with almost 90% of the genus Lactobacilli and Bifidobacteria (1). Compare this to adulthood, where we have many many different kinds of bacterial species inhabiting our digestive system, but we’ll talk more about this later.
As we grow, our microbiomes change.
Once we start eating a variety of solid food and are exposed to more people and more environments, we naturally become more populated with different strains of bacteria. The species that dominate will depend on what we eat, what bacteria we come into contact with, and the environment to which we’re exposed.
In adulthood, we become very “bacteria-rich.” So much so that we are 99% microbial and 1% “human” (2 & 3). That is to say, the microbes that inhabit our bodies have one hundred times more genes and 10-fold more cells than our own human genes and cells, respectively (we have about 10 trillion cells, whereas our bacteria have approximately 100 trillion cells).
Why is the microbiome so important?
“All disease begins with the gut” – Hippocrates
These genomes are a product of a 200,000-year co-evolution. This means, for the past 200,000 years, humans and bacteria have supported each other’s growth (and sometimes hurt it, too).
We now know that the microbiome is linked to almost every part of our health (4, 5, 6, 7, 8, & 9).
Three and a half billion years in the making, they play significant roles in (10):
Digestion
Making enzymes that help us break down vitamins and minerals
Harvesting nutrients otherwise inaccessible to us
Lowering inflammation
Contributing to glucose homeostasis
Contributing to a healthy immune system
Determining whether one is lean or overweight
Absorbing nutrients
Producing vitamins and minerals
Metabolizing carcinogens
Preventing colonization by pathogens
The Central Nervous System, our brain, and our mood
Predisposing us to many different ailments IF in dysbiosis, including:
Inflammation, autoimmunity, cancer risk, metabolic disorders, obesity, depression, nutrient deficiency
The microbiome clearly evolved to contribute something to our health!
In our next post, we will delve into what some of the research says about the microbiome- how YOUR microbes can have completely different outcomes on glucose responses, inflammation, disease risk, and how we can help flourish the right microbes to benefit our health.
References:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3593662/pdf/nihms417420.pdf Garrido, D., Ruiz-Moyano, S., Jimenez-Espinoza, R., Eom, H. J., Block, D. E., & Mills, D. A. (2013). Utilization of galactooligosaccharides by Bifidobacterium longum subsp. infantis isolates. Food microbiology, 33(2), 262-270.
http://www.sciencedirect.com/science/article/pii/S0163725811000362 Cani, P. D., & Delzenne, N. M. (2011). The gut microbiome as therapeutic target. Pharmacology & therapeutics, 130(2), 202-212.
http://onlinelibrary.wiley.com/doi/10.1111/j.1462-2920.2005.00959.x/full Abdo, Z., Schüette, U. M., Bent, S. J., Williams, C. J., Forney, L. J., & Joyce, P. (2006). Statistical methods for characterizing diversity of microbial communities by analysis of terminal restriction fragment length polymorphisms of 16S rRNA genes. Environmental microbiology, 8(5), 929-938.
https://www.ncbi.nlm.nih.gov/pubmed/22940212 LeBlanc, J. G., Milani, C., de Giori, G. S., Sesma, F., Van Sinderen, D., & Ventura, M. (2013). Bacteria as vitamin suppliers to their host: a gut microbiota perspective. Current opinion in biotechnology, 24(2), 160-168.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367209/ Carabotti, M., Scirocco, A., Maselli, M. A., & Severi, C. (2015). The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of gastroenterology: quarterly publication of the Hellenic Society of Gastroenterology, 28(2), 203.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3735932/#bib31 Den Besten, G., van Eunen, K., Groen, A. K., Venema, K., Reijngoud, D.-J., & Bakker, B. M. (2013). The role of short-chain fatty acids in the interplay between diet, gut microbiota, and host energy metabolism. Journal of Lipid Research, 54(9), 2325–2340. http://doi.org/10.1194/jlr.R036012
https://www.ncbi.nlm.nih.gov/pubmed/11581570 Alexander, C., & Rietschel, E. T. (2001). Invited review: bacterial lipopolysaccharides and innate immunity. Journal of endotoxin research, 7(3), 167-202.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2327198/ Yoshino, S., Sasatomi, E., & Ohsawa, M. (2000). Bacterial lipopolysaccharide acts as an adjuvant to induce autoimmune arthritis in mice. Immunology, 99(4), 607–614. http://doi.org/10.1046/j.1365-2567.2000.00015.x
Dietert, R. R., & Silbergeld, E. K. (2015). Biomarkers for the 21st century: listening to the microbiome. Toxicological Sciences, kfv013.
https://www.amazon.com/Good-Gut-Taking-Control-Long-term-ebook/dp/B00OZ0TOV2
