When you think of the microbiome, you probably think of your gut. But bacteria live all over your body. And they’re incredibly numerous; you play host to about as many microbes — a hundred trillion of them — as you do human cells.

As my guest will explain, these microbial ecosystems are not only ubiquitous but hugely influential for your health — impacting everything from your weight and mood to your risk of developing many diseases.

Dr. Brett Finlay is a microbiologist and the co-author of The Microbiome Master Key. Today on the show, Brett explains what the microbiome is, how modern life — including our overemphasis on hygiene — has damaged it, and how the quality of your microbiome is connected to nine of the top ten leading causes of death, as well as everything from depression to Parkinson’s. Brett also shares how we can boost the health of our microbiome, including whether probiotic supplements are effective, how something as simple as flossing your teeth can cut your risk of Alzheimer’s by 50%, and why you might want to let your dog lick you in the face.

• Let Them Eat Dirt documentary
• AoM Article: How and Why to Eat More Fiber
• AoM Article Don’t Be a Stick in the Mud — Why You Should Let Your Kids Get Dirty
• Probiotic gum

• Brett’s faculty page

All the neurochemicals in the brain have to do with life in the present. Except for one: dopamine. Dopamine is the one neurochemical that looks to the future. It anticipates what may be to come and drives you towards it.

That can be a good thing — dopamine is one powerful motivator — but it also has its downsides. Here to help us understand how the most important chemical in the brain works and how to deal with its pitfalls is Michael Long. Michael is a trained physicist turned writer whose latest book is Taming the Molecule of More. Mike and I discuss how dopamine, for better and worse, makes you want what you don't have. He shares what causes low dopamine activity, how to know if you're experiencing it, and what increases dopamine. We then talk about how to deal with the consequences of dopamine in some of the scenarios in which it plays a role — like losing the spark in a relationship and getting stuck in a smartphone scroll habit — and why so much of taming dopamine comes down to living in the here and now. We end our conversation with why The Great Gatsby is really a novel about dopamine and the fundamental answer to not letting the dopamine chase lead you around.

• Mike's previous appearance on the AoM podcast
• AoM Article: How to Do a Dopamine Reset
• AoM Podcast #745: Do You Need to Take a Dopamine Fast?
• AoM Article: Your Life Explained Through Dopamine

• • • Taming the Molecule website