How the Genetic Game was Turned on its Head by Microbes
By Dr. Will Bulsiewicz
(Book Excerpt from Fiber Fueled)
Since 1953 when Professors James Watson and Francis Crick described the structure of DNA, it seemed that genetics held the keys to understanding human health and disease. Nearly fifty years later and after a massive coordinated international effort among one thousand scientists across twenty institutions, the Human Genome Project culminated in 2000 when the human genetic code was unlocked for the first time. This was as big as it gets from a scientific perspective.
Sadly, for all the hype, the returns on this breakthrough have been incredibly disappointing. You’ve no doubt noticed that we have not resolved all medical problems since the year 2000. Why did genetics alone not heal us? Well, we have since discovered by studying identical twins that less than 20 percent of disease is based on genetics. Yes, there are some, such as cystic fibrosis and Down syndrome, where if you have the genes then you get the disease. But taking all chronic disease across the board, more than 80 percent of your disease risk is determined by your environment and exposures during your lifetime. There’s a silver lining here. You are not the victim of the genes you were born with. You may have certain predispositions—we all do. But you ultimately control your health destiny, in large part through the effects of your diet and lifestyle on your microbiome.
In a letter to Science magazine in 2001, Professor Julian Davies warned that decoding the human genome was not enough to understand human biology because there are more than a thousand bacterial species living in and on the human body and they are critically affecting human life. We previously noted that there are more bacteria than cells in the body, but let’s take it a step further and talk genetics. More than 99 percent of your DNA comes from microbes. Yes, your genes are less than 1 percent human! Further, our human genomes are actually identical—up to 99.9 percent the same. But our microbiomes may be as much as 90 percent different from one person to the next.
Beyond holding the cards on a genetic monopoly, our gut microbes also exert tremendous power over the expression of your genes through something called epigenetics. Imagine your gut microbiota as controlling a light switch and the wiring behind the wall is your genetic code. The gut microbiota is not changing the wiring behind the wall, but it can turn the lights on or off. You can’t change your genetic code, but you can effect which genes get turned on or off. That is insanely powerful, if you think about it.
An example of this concept of epigenetics is celiac disease. Celiac disease is a condition in which the immune system decides that gluten is the enemy. Gluten is a protein found in wheat, barley, and rye. Every time someone with celiac disease consumes gluten, the immune system lashes out and attacks their intestine, causing inflammation that shows up as diarrhea, weight loss, and abdominal pain. This is incredibly dangerous because people with celiac disease who continue to consume gluten can develop small intestine lymphoma, which is nearly universally fatal.
Celiac is a genetically motivated disease. This means that you must carry the gene for celiac to get it. If you don’t have the gene, you can’t have the disease. About 35 percent of Americans carry the gene for celiac but only 1 percent manifest the disease. In the last fifty years we’ve seen a 500 percent increase in celiac disease. So what explains the rapid increase? Clearly not a shift in genetics during that brief period. So what is it that determines who ultimately expresses the gene? Dr. Elena Verdú from McMaster University in Canada showed us through a series of eloquent studies that there are three criteria that must be met to develop celiac disease: 1)presence of the gene, 2) exposure to gluten, and—you guessed it, 3) alteration or damage to the gut microbiota.
We thought that cracking the human genome would produce major breakthroughs in medicine because we thought that human health was primarily determined by genetic makeup. Nope. We are a superorganism with a genetic makeup dominated by the invisible microbes within us. And this is actually a good thing! Rather than worrying about the 0.5 percent of your DNA that you simply cannot control, let’s optimize our microbiome through diet and lifestyle and enjoy the positive effects it has on 99.5 percent of our DNA plus our epigenetic expression. It’s time to transform your health from the inside out!
What once was dismissed as poop is now the star quarterback for human health. Yes, it can be intimidating that most modern diseases have been connected to damage to the gut microbiome. But remember, we are not helpless victims stricken with disease. We have the power of science on our side, and for the first time in human history we actually know enough about the gut microbiota to understand it and start to use it to our advantage. You can use diet and lifestyle to rebalance your gut microbes. You’ll see your digestion, immune system, metabolism, hormones, cognition, and gene expression become optimally aligned, and you’ll transform into the microbempowered superhuman that you are.
To view the scientific references cited in this article please visit me online at www.theplantfedgut.com/research/.
From FIBER FUELED by Dr. Will Bulsiewicz, published by AVERY, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2020 by Will Bulsiewicz
Dr. Will Bulsiewicz, MD, MSCI, is a board-certified, award-winning gastroenterologist. Dr. Bulsiewicz is a graduate of Georgetown University School of Medicine and was chief medical resident at Northwestern Memorial Hospital and chief gastroenterology fellow at the University at North Carolina Hospital. He won the highest award given in both his residency and fellowship. More
Build Up Immunity With A Fiber Fueled Diet
An Evening Lecture with Dr. Will Bulsiewicz
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