What Is Your Microbiome? And Three Things That Could Change It


The microbiome could change the way we think about cancer and its treatment.

Time for a gut check: What do we know about the trillions of bacteria swarming in and around our bodies at any given moment?

The answer: not as much as we’d like. That’s why researchers at Memorial Sloan Kettering and beyond are studying the microbiome. This is the community of bacteria, viruses, fungi, and other organisms found throughout the body but especially in the digestive tract, mouth, and genitals, plus on the skin. Researchers are looking into how the contents of a person’s microbiome might influence his or her health.

“It’s a very hot topic, and I think it has the potential to answer many questions about the causes and outcomes of diseases, including cancer,” says MSK gastroenterologist Robin Mendelsohn. “It may help us understand why some people develop diseases and others don’t, and even why some people respond to treatments and others don’t.”

Having a low diversity of microorganisms has been shown to possibly be associated with different diseases, like cancer, obesity, and irritable bowel syndrome.
Robin Mendelsohn gastroenterologist

Scientists don’t yet know the exact role of the microbiome in human health. Though they have seen that a microbiome with various strains of bacteria is best.

“Having a low diversity of microorganisms has been shown to possibly be associated with different diseases, like cancer, obesity, and irritable bowel syndrome,” says Dr. Mendelsohn.

The implications for people with cancer are just scratching the surface. Immunotherapy, which harnesses a person’s own immune system to attack cancer, is revolutionizing how cancer is treated, and the microbiome may play a role, Dr. Mendelsohn says. A healthy microbiome may also help people with cancer who have recently had bone marrow transplants with their recovery.

“The microbiome might be involved in the prevention of cancer, the progression of cancer, the side effects of treatment, and long-term survival,” she says.

Changing Your Microbiome

Your microbiome changes on a day-to-day basis depending on all sorts of factors. But there are ways to change its content significantly over time. One is a fecal transplant, in which doctors transplant stool from a healthy person to an unhealthy person. Fecal transplants are currently approved for people with a Clostridium difficile infection, which wipes out the contents of the microbiome.

Not all methods for creating a more diverse microbiome are as invasive, though. Dr. Mendelsohn says modifications in the following could all play a role.

  1. Diet
    “Diet is probably the easiest way for someone to change his or her microbiome,” Dr. Mendelsohn says. But her advice goes beyond the conventional wisdom to eat more yogurt for its beneficial bacteria. “The amount of probiotics you’re getting from yogurt is questionable,” says Dr. Mendelsohn. That’s because both stomach acid and the pasteurization process kill off most of the bacteria present. You’re more likely to benefit from prebiotics, which fuel the beneficial bacteria in your body. Prebiotics are found in fiber-rich foods, like oatmeal, whole grains, fruits, and vegetables. If you’re eating a well-balanced diet, chances are you’re already getting a good amount of prebiotics.
  2. Behavior
    There are data to suggest that regular exercise, enough sleep, and a low stress level may help the bacteria in your body thrive.
  3. Antibiotics
    Each antibiotic is different, and each person’s microbiome responds differently, but even just a single dose of an antibiotic can alter the contents of the microbiome, says Dr. Mendelsohn. That’s not a reason to swear them off, though. “Antibiotics save lives and should be used when needed,” she says. “But the doctor and patient need to decide if they’re necessary.”


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I am Stage 4 TNBC currently on eribulin and Pembro. I have been on strong antibiotics for much of past six months (drips for 5 days at a time after pneumonia pneumonitis and liver malfunction thereafter pill form). I eat healthy and diverse. Pls can you advise probiotic supplement that will not interfere with treatment. Much appreciated.,

Dear G, we’re sorry to hear about your diagnosis. This is something you should discuss with your healthcare team. They are the ones who are familiar with your complete medical history. Thank you for your comment, and best wishes to you.

67, 5'8", 183 lbs, limited exercise, diet could be better, want to become healthier. What steps are vital to begin.

Dear Elaine, one thing that may be helpful for you is to consult with a dietitian. If you are thinking about starting a new exercise plan, you may also want to consult with your doctor first. Thank you for your comment, and best wishes to you.

I take Wallaby plain organic yogurt and Align. Are these going to help?

Dear Marianne, there is limited evidence on how probiotics in the food affect overall health of the microbiome. This is something that scientists continue to study. Thank you for your comment.

I've been reading and following plenty studies from different research groups. Also, the progress from companies like Viome and similar.
Here are my two cents. While we don't know much about the symbiosis between the gut microbiome and us, we do have a huge database that can be searched for patterns thanks to machine learning. Different DNA lines will show different affinities with groups of bacteria, virus and fungi. Like Petri Dishes, as babies through lactation, we establish a relationship. Studies will show that the evolution of this symbiosis will determine health (homeostasis) or illnesses (dysbiosis). But the biggest problem will be the fact that each of us has a different set of DNA, meaning there will be no -one solution fits all- but again, thanks to machine learning patterns will be found, reducing to treatment groups. So, it's just a matter of time.
Keep up the good work.

Have they researched the roll colostrum and or Brest milk could play in a biom deficient gut?

Dear Donna, this is something that is being studied at other research centers but not something that is being looked at at MSK. Thank you for your comment.

Thank you for bringing the gut microbiome into the spotlight and providing simple actionable tips to promote a healthy microbiome.
It would be nice to see what exactly MSK researchers are studying. For instance, there is increasing data supporting a healthy microbiome ability to increase effectiveness of immunotherapy drugs, such as PD-1, in mice. It makes sense since these microbes are known to modulate immune responses. Wouldn't be nice to incorporate microbiome screening within the numerous clinical trials MSK is involved in?



Dear Valerie, MSK has an active research program in this area. You may be interested to read this article on the microbiome and BMTs. Also this one on the microbiome and immunotherapy.

Thank you for your comment.

Dr. robin Mendelsohn saves my life with FMT after a harrowing year of recurrent CDiff during cancer treatment. She is a wonderful person. Forever thankful!

Just want to thank you for this insightful hopeful researched article.

I had breast cancer and finished all my treatments. I was doing well then all of a sudden I started losing weight, abdominal pain, and not being able to eat more than one meal a day. I had a colonoscopy and endoscopy. The endoscopy when biopsies showed something in my small intestines so they send me in for blood work for celiac. That test was negative. I’m still having trouble would you recommend a second opinion?

Dear Melissa, we’re sorry to hear you’re going through this. If you were not able to get any answers about what is causing your symptoms then it would make sense for you to see another doctor. Thank you for your comment and best wishes to you.