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

Human stomach with viruses and bacteria. Vector illustration

Human stomach with viruses and bacteria. Vector illustration

Tips for Optimal Gut Health

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 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 how these bacteria 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 they can be turned on and off. They’re influenced by any number of environmental factors, and one of the most important of these 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 Dutch scientist Antonie van Leeuwenhoek, known as “the father of microbiology”. He noted striking differences between the microbes living in different parts of the human body and 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 we can use this knowledge to improve an individual’s health.”

Scientists are cautious about drawing conclusions yet but research points in directions that show great promise. When intestinal microbes from lean mice are transplanted into obese mice, the obese mice lose weight. When we reverse the procedure, the lean mice gain weight. In humans, transplanting intestinal bacteria from a healthy person into a sick one can effectively treat certain intestinal infections. While it’s not yet clear exactly what constitutes a healthy microbiome, scientists believe that a diverse population in the gut is beneficial – that a diverse environment is more resilient, and therefore more resistant to invasion by disease-causing organisms. “We also know 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 internal ecosystems, we begin to see patterns that might help us improve the biodiversity and robustness of our guts.”

For example, scientists believe that antibiotics–both in prescribed drugs and in the feed of the animals we eat–diminish colonies of helpful bacteria. And our attempts to reduce our exposure to bacteria in the food we eat, and our efforts to wash them away with anti-microbial products like hand soap and sanitizer may actually diminish the diversity of our microbiome. In some rural populations – where people live on farms, eat largely plant-based diets, and are regularly in contact with animals – people have more diverse microbiomes, and lower rates of chronic conditions like obesity, type-2 diabetes, allergies, asthma, and cardiovascular disease.

jars of colorful pickled beets, green beans, and carrots

Eat some fermented foods each day.

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, kombucha – to your diet.
  • Let kids play in the dirt and pet the dog!

Dr. Nunley stresses that we are 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 MD
Marsha Nunley MD
I am an internist, trained and experienced in Western Medicine, who believes that illness and disease are best treated by working to discover their underlying causes. Come to me for bioidentical hormones, advice on healthy aging, and whole-body medicine.