The term "psychobiotic" might sound a bit ominous, but rest assured, the psychobiotic diet isn't something out of Hannibal Lecter’s kitchen. In reality, "psychobiotic" refers to microbes that have the potential to enhance our mental health, and the diet is designed to nurture these beneficial microbes. Drawing from research by the highly productive lab of John Cryan and Ted Dinan, this diet is a modified Mediterranean plan, rich in fiber and fermented foods. These nutrients promote the growth of psychobiotic microbes, which produce substances that heal the gut and calm the mind. Full disclosure: I co-authored a book with Cryan and Dinan called The Psychobiotic Revolution, where we delve into the components of a healthy diet packed with fiber and fermented foods. While the book covers much more than I can here, their recent study, Feed your microbes to deal with stress, introduces some important new concepts.
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Since our book's publication, Cryan and Dinan have broadened the definition of psychobiotics to include not just microbes, but also prebiotics, fermented foods, and other items that enhance the diversity and stability of the microbiome. They now suggest that our diet itself can be psychobiotic. Ted Dinan coined the term "psychobiotic" in 2013, so he gets credit for the name.
In their study, 45 adults were divided into two groups: one followed a psychobiotic diet, and the other served as a control. Those on the psychobiotic diet experienced a 15% reduction in perceived stress compared to the control group. Notably, individuals who adhered more closely to the diet saw better results. This kind of dose-response effect (where a higher dose leads to a stronger response) suggests that the relationship is causal. The researchers agree, noting that “dietary approaches can be used to reduce perceived stress.” Although the effect isn’t massive, in today’s stressful world, any improvement is welcome.
So, how does this work?
The gut-brain axis is becoming more familiar, and Cryan and Dinan have played a significant role in raising awareness about it. Their research indicates that the brain affects the microbiome and vice versa.
Fiber has a profound effect on our microbiome, but those who primarily eat processed foods miss out on this crucial nutrient. While fiber isn’t for us directly, it feeds our microbes, which then produce substances like butyrate that soothe the gut lining—and can benefit the brain as well. The Standard American Diet (aptly abbreviated as SAD) deprives our good gut microbes, leading to an unstable and less diverse microbiome.
Fermented foods add live probiotics to the mix. Although most probiotics don’t permanently reside in the gut, they provide significant benefits as they pass through. Probiotic bacteria that lower pH discourage the growth of harmful microbes and support beneficial ones. A healthy microbiome is less likely to leak, preventing microbes and their toxins from entering the bloodstream. Persisting with a poor diet can lead to chronic inflammation, which is linked to various diseases and a reduced ability to cope with stress.
In summary, a diet rich in fiber and fermented foods is associated with a reduction in many common mental health issues.
So, what exactly is the psychobiotic diet?
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Since a diverse microbiome is healthier and more stable, what should we be eating? Unsurprisingly, a varied diet is needed to support a diverse microbiome. Each microbe species has its preferred food, so we need to consume many different types of fiber to satisfy their needs. A good psychobiotic diet resembles a Mediterranean diet, characterized by a wide variety of fiber-rich vegetables (like garlic, leeks, cabbage, artichokes, onions), fruits (such as berries, figs, avocados), nuts (pistachios, almonds), grains (oats, bulgur, farro), legumes (beans, lentils), healthy fats (omega-3, olive oil), seafood (salmon, shrimp), spices (oregano, basil, cinnamon, cumin, fennel), greens (arugula, spinach), and fermented foods (yogurt, kefir, cheese). The diet is also low in sugar.
Some experts recommend eating 30 different vegetables a week, which can be daunting for those of us who are familiar with only five—and mostly consume just potatoes and onions. The other three vegetables we know about are often avoided. This limited diet is why many of us experience gut problems, excess weight, and mental health issues. Are people on the Mediterranean diet healthier and happier than us? Generally speaking, yes.
If eating 30 different vegetables a week seems overwhelming, consider prebiotics. Prebiotics are fibers that feed your good microbes. It’s best to opt for a blended prebiotic to encourage diversity. While Americans typically consume only about 10 grams of fiber a day, the recommended intake is 35 to 50 grams.
To increase our resilience to the overwhelming stressors we face, the psychobiotic diet is worth considering—perhaps with some fava beans and a nice Chianti.