Q&A: The microbiome and cancer

A well-balanced diet that’s rich in plant foods, including legumes and whole grains is important for everyone, including cancer survivors. Consistent healthy choices can help prevent weight gain and decrease body fat, which are linked to better quality of life and a lower risk of cancer and cancer recurrence. In healthy individuals, eating well, exercising and maintaining a healthy weight have been shown to decrease cancer risk.

Another important and perhaps overlooked reason for maintaining a balanced diet is to promote a healthy microbiome, which can have a number of important health benefits. Below, Carrie Daniel-MacDougall, Ph.D., assistant professor of Epidemiology, answers questions about the role the microbiome plays in several health conditions, including cancer.

What is the microbiome?

The microbiome is composed of bacteria -- both good and bad -- that live and coexist inside of and around you: on your skin and eyes, in your mouth and throughout your GI tract. Your microbiome is a big part of who you are and what makes you different from everyone else. In fact, it’s bigger than all of us.   

The microbiome holds clues about what you’ve been exposed to, what illnesses you may be prone to and what treatments may be most effective. It can even tell us about your favorite foods! We are now learning how to decipher these many signals.

How does the microbiome impact your health overall?

The microbiome has been linked to obesity, inflammatory bowel disease, diabetes, heart disease and a number of cancers, such as colorectal cancer, pancreatic cancer and breast cancer. I imagine that this list will grow as we learn more about the role the microbiome plays in diet and obesity, which is linked to many diseases.

Eventually, we may be able to understand how your microbiome affects your personal health by reading your microbiome profile along with blood sugar and cholesterol levels. But for now the best answer is that balance in the microbiome promotes good health.

Can we influence the microbiome to lower cancer risk?

I think an individual’s diet is the safest place to start harnessing the microbiome for cancer prevention. Short-term studies have shown that improvements in overall dietary habits positively impact the microbiome and other markers of cancer risk. However, because these results are seen in such a short time, they are just as easily reversible. Therefore, if you’re trying to prevent cancer, the dietary changes have to be sustained long-term. 

Why is the microbiome important for cancer patients and/or survivors?

Given that the microbiome and the immune system are intrinsically linked, harnessing the microbiome could be important for everything from side effects to treatment response to long-term survival. This is an area of active research, but there aren’t any safe and proven answers yet. Based on a lack of evidence, I would not suggest that a patient in active treatment try to independently manipulate his or her microbiome as that may easily do more harm than good.

What can people do personally to affect their microbiomes?

In healthy people, it’s primarily diet and medication use that impact the microbiome. Your microbiome depends on you for food, so you decide what it’s eating today and every day. Tweaking your diet therefore is a natural way to influence the bugs you have, fostering the good and crowding out the bad.

Fiber-rich vegetables, fruits and whole grains, which have long been recommended for cancer prevention, are also good “pre-biotic foods” that can help feed the good bacteria you already have.

Probiotics may sometimes be recommended by your doctor after taking antibiotics or other situations that can wipe out your microbiome. You can also get probiotics through food sources, such as yogurt and other fermented dairy products.

What current research are you working on in this area?

I am currently interested in how prebiotic foods and overall dietary patterns impact the microbiome and colorectal cancer risk. After we observed the diets and microbiomes in both healthy people and those with precancerous colorectal polyps, we were excited by the results. However, we have more to learn.

So, we’ve initiated our first trial on the diet and microbiome here at MD Anderson. Beans have long been linked to cancer and heart disease prevention. Our goal is to find out if beans can improve the healthy bacteria in the digestive system and reduce the effects of obesity on cancer risk.

For more information about participating in the trial, call 713-792-2062 or email begone@mdanderson.org.