The Microbiome: What Is It and How Does It Affect You?

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Functional Medicine Specialist Dr. Marsha Nunley with H.E.A.L. Medical Provides Tips for Optimal Gut Health.

Dr. Marsha Nunley

Genes provide an inherited potential but genes can be turned on and off and are influenced by any number of environmental factors, one of the most important of which is the action of the bacteria in the gut.

Our genes determine who we are. Thanks to a vast international undertaking called the Human Genome Project, we now know that the human genome – the complete set of genetic information for each person – is comprised of about 24,000 genes. But it turns out that the makeup of the human organism isn't determined only by our human genes but also by the bacteria that live on and in us, most of them in our intestines. There are trillions of these bacteria and they and the genes they harbor make up the human microbiome. And just as the Human Genome Project mapped our human genes, the Human Microbiome Project is a worldwide effort to understand the role these bacteria play and how they influence our health.

“Our genes do not determine a fixed destiny,” says functional medicine specialist Dr. Marsha Nunley, founder of H.E.A.L. Medical. “Genes provide an inherited potential but genes can be turned on and off and are influenced by any number of environmental factors, one of the most important of which is the action of the bacteria in the gut. Our microbiome affects our health in ways we are just beginning to understand. So the question becomes 'what can we do to create a bacterial environment that supports optimal health and well-being?'”

Studies of the bacteria that live with us date to the seventeenth century and the work of Antonie van Leeuwenhoek, the Dutch scientist known as “the father of microbiology” and for his contributions to the development of the microscope. He noted striking differences between the microbes that live in different parts of the human body and between samples taken from people in various stages of health and disease. “We've had the ability to observe these differences for centuries,” says Dr. Nunley. “What's different – and exciting – now is that new molecular techniques are making it possible to understand why these differences exist and use this knowledge to improve an individual's health.”

Scientists are cautious about drawing conclusions yet but their research points in directions that show great promise. When intestinal microbes from lean mice are transplanted into obese mice, the obese mice lose weight and when the reverse procedure is performed, the lean mice gain weight. In humans, transplanting the intestinal bacteria from a healthy person into a sick one effectively treats certain intestinal infections. It is not yet clear exactly what constitutes a healthy microbiome but it is believed that a diverse population in the gut is beneficial – that a robustly diverse environment is more resilient and resistant to invasion by disease-causing organisms. “It is also known that the diversity of the microbiome is fragile and that in industrialized Western populations the microbiome is less diverse than in rural, less-industrialized areas,” says Dr. Nunley. “In examining the reasons for our less diverse ecosystems, we can begin to see patterns that can help us improve the biodiversity and robustness of our guts.”

For example, antibiotics, both in prescribed drugs and in the feed of the animals we eat, is believed to diminish colonies of helpful bacteria. And we've done everything we can to reduce our exposure to bacteria in the food we eat and through the use of anti-microbial products such as soap and hand sanitizer. It appears that rural populations – people who live on farms, eat largely plant-based diets, and are regularly in contact with animals – have a more diverse microbiome than highly industrialized populations and much lower rates of chronic conditions such as obesity, type-2 diabetes, allergies, asthma, and cardiovascular disease.

Tips for a healthy microbiome
Dr. Nunley suggests the following tips to improve and maintain the health of our microbiome:

  •     Use antibiotics only when medically necessary and avoid meat treated with antibiotics.
  •     Eat a wide variety of organic whole grains and plant-based foods.
  •     Don't eat anything with a long list of unpronounceable ingredients.
  •     Add fermented foods – yogurt, kimchi, sauerkraut – to your diet.
  •     Let kids play in the dirt and pet the dog!

Dr. Nunley stresses that it is early in the process of understanding the role of the microbiome. “We still have a lot to learn and the future promises exciting developments. But we know enough now to start properly nurturing the microbes that share our bodies with us. They will return the favor by paying dividends in improved health and well-being.”    

Marsha Nunley, M.D., founder of H.E.A.L. Medical is board-certified in internal medicine, geriatric medicine, and palliative care. Dr. Nunley specializes in functional medicine, a systems-based approach to treating the whole person.

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Melissa Chefec
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