Nourish the “second brain” in your gut

The connection between diet, gut health, and mental health

June 30, 2022
Diet, Food, Healthy

Your brain and your digestive tract are not as independent as they seem. Here’s how you can change your diet and lifestyle to support your gut bugs and mental wellness.

The gut-brain dialogue

For the most part, the brain is “sealed off” from the rest of the body by the blood-brain barrier. But, in fact, the gut and the brain have an ongoing dialogue.

The main two-way channel of direct gut-brain communication is the vagus nerve, a superhighway that runs between the central and enteric nervous systems. Yet it’s becoming clear that the micro-organisms residing in the gut also contribute to the messages that reach the brain.

Meghan Hockey, accredited practising dietitian and nutrition researcher says, “The gut and the brain are constantly talking to one another through microbial metabolites and immune, neuronal, and metabolic pathways.”

Different gut bugs, different brain-related conditions

Scientists are starting to uncover the gut correlates of brain-related conditions. For example, individuals with major depressive disorder tend to have a different set of gut microbes than non-depressed individuals.

Different patterns in gut microbial communities have also been found in people with anxiety, schizophrenia, multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, and, neurodevelopmentally, even in autism spectrum disorder.

While this doesn’t mean the gut microbes caused these conditions, it does mean that scientists can start looking at whether intervening at the distant site of the gut can affect how these conditions play out—or perhaps whether it’s possible to prevent the condition in the first place in susceptible individuals.

The contributions of gut microbes are under investigation, too, in several conditions that are widely understood to be confined to the digestive tract: inflammatory bowel disease and irritable bowel syndrome.

Using diet to shape gut microbes

Hockey says now that we know gut bacteria are intricately involved in gut-brain communication, it bolsters the idea that nutritional changes can have an impact on brain health.

Eat more plant-based foods

While there’s no diet or supplement that alone can alleviate mental illness, Hockey emphasizes that plant foods feed the gut microbes in multiple ways that support brain health.

When advising clients, she says, “As a first step, I recommend increasing the intake and variety of plant foods such as vegetables, fruits, beans, lentils, nuts, seeds, and whole grain cereals. These foods contain a variety of fibers and polyphenols that can promote the growth of beneficial bacteria within the gut.”

Include probiotics and prebiotics

Probiotics are a potential way to achieve positive changes in the gut microbiota, and some have shown promise for helping depression, although most available probiotic strains have not been studied for their specific effects on the brain or mental health. Ditto for prebiotics, which are substances that act as “food” for beneficial gut microbes.

Remember that variety is key

Hockey advises looking at the big picture. “Overall diet quality and patterns, rather than individual foods, matter most to mental health,” she says. “We don’t eat individual nutrients and foods in isolation; we eat meals and snacks which contain a variety of foods and nutrients that interact with one another.”