Education and outreach
How to hack your microbiome for lifelong health
In this Q&A, professor Brett Finlay discusses tips from his new book, The Microbiome Master Key, on how to leverage the microorganisms in your body to promote healthy living and aging.

Dr. Brett Finlay gives a talk about the microbiome and healthy aging following the publication of his new book.
By Sarah Anderson and Emily Cooke
From probiotic pills to skincare products to dedicated meal plans, the microbiome is all the rage in the health and wellness space. That’s because scientists have come to appreciate that the trillions of microbes – bacteria, fungi, and other microscopic organisms – that live in your gut, on your skin, and beyond have a huge impact on the body as a whole.
“This has been a major shift in our thinking. We’ve known that microbes can cause infectious diseases for centuries, but even a decade ago, we didn’t have a clue about all of the roles that the microbiome plays in both health and disease,” said Dr. Brett Finlay, a professor at UBC’s Michael Smith Laboratories, Department of Microbiology and Immunology, and Department of Biochemistry and Molecular Biology.
A leading expert in how microbes affect health for better and for worse, Finlay teamed up with his daughter, gerontologist Jessica Finlay, to publish their new book The Microbiome Master Key. Building off of their 2019 book The Whole-Body Microbiome, the duo continues to explore the unexpected ways in which microbes influence areas ranging from cognition and mood to immunity and susceptibility to disease. The authors dissect the latest microbiome research, dispel common myths, and provide simple, science-backed tips on how to leverage your microbiome to promote healthy living and aging. In this Q&A, Brett Finlay (BF) discusses some key take-home messages from The Microbiome Master Key.
What does a healthy microbiome look like?
BF: A healthy microbiome is difficult to define. Everyone has a unique microbiome, so there’s no one “perfect” microbiome. Generally speaking, it’s good to have lots of different kinds of microbes, just as diversity is beneficial within an ecosystem. It’s not so good to have microbes that trigger inflammation because they can damage the body and contribute to the aging process.
What can a person do to improve the health of their unique microbiome?
BF: The nice thing about the microbiome is that, unlike your genes, you can change it. With certain dietary interventions, you’ll see a difference in the microbiome within a few days. Stay away from fad diets and focus on proven ones like the MIND diet, which combines the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets. These diets entail eating less red meat, white sugar, and white flour and eating more fruits, vegetables, nuts, olive oil, and fish. Incorporate fermented foods and get lots of fiber, and above all, stay away from ultra-processed foods. And while intermittent fasting initially improves the microbiome, longer-term studies suggest that it is actually harmful. Instead, avoid snacking between dinner and breakfast the following day.
Exercise is another effective way to push your microbiome to a healthier state, which then contributes to your health and longevity. On average, one minute of exercise adds about 5 to 7 minutes to your life, so get moving!
Other things like decreasing stress, getting a good night’s sleep, and having a strong social community contribute to the health of your microbiome and therefore your overall health.
What skincare approaches do you recommend to maintain a healthy skin microbiome?
BF: A healthy diet also leads to healthy skin, but in terms of external skincare, stick to soap and water, and wash less frequently than you probably do. Extensive harsh washing removes healthy microbes on the skin, which then allows harmful microbes to grow and cause skin problems and infections.
What is the connection between the microbiome and brain health?
BF: We now understand that microbes in the gut have a profound effect on brain health. We don’t have all the details yet, but communication between the gut and brain via the so-called gut-brain axis has been linked to mental health conditions such as anxiety and depression as well as neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease. Our research found that following the MIND diet can delay the onset of Parkinson’s disease by up to 17 years by altering the gut microbiome. So, you can do a lot for your brain health through your gut.

Dr. Brett Finlay signs a copy of his new book.
The Microbiome Master Key has chapters on COVID-19 and cancer. What role does the microbiome play in these diseases?
BF: We’ve learned that microbes have a significant impact on the immune system. For COVID-19, a person’s microbiome plays an important role in the intensity of their infection and can actually be used to predict the severity of their disease. The microbiome also affects whether an individual develops long COVID.
The data on the connection between the microbiome and cancer is not as robust. But we do know that microbes influence whether checkpoint inhibitor therapy, a type of cancer immunotherapy, will work for a patient.
Do you recommend taking probiotics or other microbiome-targeted supplements?
BF: No; most don’t work. Instead, I recommend focusing on diet, exercise, and the other ways you can improve the health of your microbiome naturally. If you do want to learn about probiotics that are effective for treating certain diseases, visit probioticchart.ca for a list of these probiotics and the scientific evidence that they work from clinical trials.
There is a lot of misinformation surrounding the microbiome. What do you think is the most important “microbiome misconception” to dispel?
BF: Certain microbiome-linked diseases can be treated by transferring feces from a healthy donor to a recipient, but don’t try this at home! Fecal transfers must be done by a professional in a clinical setting: The donor needs to be screened for infectious agents, and if the recipient suffers a perforated bowel, they could die of sepsis. That said, the YouTube videos of DIY fecal transfers are quite humorous– just don’t do it yourself!