Can Eating Right Prevent Depression?
Photo by Joel Filipe
There’s been considerable buzz about the microbiome, the trillions of gut bacteria that live in our digestive system. We are learning that these bacteria have an important impact on obesity, inflammation, and many chronic diseases. And recently, scientists have uncovered connections between the microbiome and mental health via the gut-brain axis, an intriguing system connecting the digestive system to the brain. A lot of this recent research is in The Psychobiotic Revolution, a book that floored me.
The co-authors, science journalist Scott Anderson along with researchers, Drs. John Cryan and Ted Dinan, write about how gut bacteria produce neurotransmitters that reach the brain through the gut-brain axis and impact mood and wellbeing. “Psychobiota” is a new term that’s been coined for these mood and brain enhancing bacteria.
For example, 90% of serotonin, a neurotransmitter that makes us feel good, is produced in the gut with the help of bacteria. To treat depression, psychiatrists regularly prescribe antidepressants that help to increase the availability of serotonin in the brain.
In addition to the book, a new study published in Nature Microbiology looks at the microbiomes of two European populations of about 1000 people each, the first time a study like this has been done on such a wide scale. In both groups, the researchers found that subjects with depression or a low quality of life were missing two species of gut bacteria, Coprococcus and Dialister. Individuals diagnosed with severe clinical depression in the study also lacked these two bacteria. But these gut bacteria were present in those who were not depressed and reported a higher quality of life.
If you’re half as intrigued as I was, here is a more detailed synopsis of the study.
This eye-opening new research leads to the obvious question: are there foods that could alleviate or prevent depression? This study shows the correlation between bacteria and depression, not causation, but still, the answer seems to be leaning toward yes. Presumably, these two specific bacteria could be characterized as good bacteria that we know promote health. High fiber foods, including fruits and vegetables, are known as prebiotics and feed the good bacteria in the gut. Some examples of top prebiotic-rich foods are dandelion greens, Jerusalem artichokes (sun chokes), garlic, onions, leeks, asparagus, and bananas.
Probiotics are foods that contain live bacteria which are used to improve the gut’s balance of good versus bad bacteria (which can cause digestive problems and inflammatory conditions). Good bacteria are found in yogurt with “live, active cultures”, kefir, and fermented foods, like pickles, sauerkraut, kimchi, miso, and kombucha. Probiotics are also sold as supplements and many believe there are benefits of taking these while on antibiotics, which can wipe out our good gut bacteria colonies. Probiotics can also help address multiple health conditions, but they are not yet FDA regulated and can be expensive. I prefer to get pre- and probiotics from food rather than from supplements for everyday gut health.
For thousands of years, Ayurveda, a traditional medical system originating in India, has understood the correlation between digestive and mental health and prescribes diet practices and therapies that target the mind through the gut. In fact, Ayurveda teaches us that the home of health, including mental health, is in the gut. It’s now wonderful to see yet another example of modern science proving that food is actually medicine and that what we eat plays a fundamental role in mental and overall health.
I learn from the people I work with every day. Years ago, when one my patients told me that he noticed french fries and ice-cream worsened his mood almost immediately, I found it a bit mysterious. But more recently, I’ve been able to tell him that now we have the science that backs up his “gut feeling”. Like the ancient teachings of Ayurveda, he was years ahead of this recent wave of knowledge.