Your immune system is largely dependent on it, and more than 99% of your genes come from this, not your chromosomes. Yet it's been lost through short-sighted practices and technology installations. Isn't it time we started leaning on the wisdom of our ancestors?
How Your Microbiome Influences Your Immune System

STORY AT-A-GLANCE
Your immune system and gut microbiome share a symbiotic relationship and your immune function is largely dependent on the state of your gut
More than 99% of your genes come from microbes, not your chromosomes
The best predictor of future health is your gut microbiome at birth. C-section and antibiotic regimens — both in the mother and the baby — are known to degrade the baby’s microbiome, but can be compensated for
Healthy microbiomes are more connected to what your ancestors had that has been lost through short-sighted practices and technology installations. Trying to head toward that is much more constructive than trying to completely overhaul something to a group of microbes your ancestors never saw
Aside from the vaginal tract, the baby also receives valuable microbes via skin-to-skin contact, including oral contact with breast tissue, as well as from the breast milk, which is why breastfeeding is so important and can impact your child’s health well into the future. Environmental exposures from soil, food and animals also play a role
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This article was previously published February 7, 2021, and has been updated with new information.
In this interview, Rodney Dietert, Professor Emeritus of immunotoxicology at Cornell University, reviews the interrelationship between your immune system and your gut microbiome.
He's spent several decades researching and teaching students about the immune system. As noted by Dietert, your gut microbiome is crucial not just for immune function, but also for your health status in general, as it affects nearly all other physiological systems.
He first became aware of the importance of the gut when given the opportunity to write a research paper about which biomarker would be the best to predict the future health of a baby.
"I thought that was a really intriguing question to develop a paper around," he says. "And, I was pretty sure decades of work on the immune system in the young, prenatal and neonatal, meant that I had an answer.
I became very frustrated because I wrote a couple of paragraphs and it was unpersuasive, and went to bed extremely frustrated. I woke up in the middle of the night from a dream with what to me was an answer.
The answer was that it was the extent to which the newborn became complete or completed itself, and that that self-completion is really the installation of the microbiome, largely from the mother, but both parents contributing; vaginal delivery when possible, skin-skin contact, and then of course, followed up with prolonged breastfeeding when possible."
Ancestral Microbiomes
He points out that "more than 99% of your genes are from microbes, not from your chromosomes." You have approximately 3.3 million microbial genes, mainly bacterial. Across the entire population of humans, there are just under 10 million different microbial genes, so you won't necessarily have all of them.
You also have 22,000 to 25,000 chromosomal genes (these genes are what were analyzed through the Human Genome Project), which means you only have about 2,000 more chromosomal genes than an earthworm. As noted by Dietert, since we have about 3.3 million microbial genes, that means we're more than 99% microbial, genetically.
This is why he concluded that the gut microbiome at birth would be the best predictor of future health. Granted, your microbiome can be altered through diet and environmental exposures, and that will impact and influence your health throughout your life. But initially, the infant microbiome is the best overall predictor of future health.
"That led to a whole host of other lectures, books, scientific journal articles and an appearance in the documentary movie, 'MicroBirth,' which is a wonderful film. It won the life science award in 2014 for documentary films. That launched a second career, really, as a result of a dream, and paying attention to that versus the linear progression of 30-plus years of research."
According to Dietert, there's really no single measure of any particular bacterial species that will give you a definitive answer to what your health will be like. Rather, the most important predictive aspect is the seeding process. If the baby goes through an ideal seeding process at birth, he or she stands a greater chance of experiencing good health.
Healthy microbiomes are more connected to what your ancestors had that has been lost through short-sighted practices and technology installations. Trying to head toward that is much more constructive than trying to completely overhaul something to a group of microbes your ancestors never saw. ~ Rodney Dietert