For years neuroscientists have been trying to correct the old assumption that our minds are reducible to our brains. Research into what is known as the gut microbiome, for example, has shown that mood and mental health are intimately linked to the functioning of an ecosystem of microorganisms within the digestive system. As researchers write in the Journal of Neuroscience, “experimental changes to the gut microbiome can affect emotional behavior and related brain systems [and] may play a pathophysiological role in human brain diseases, including autism spectrum disorder, anxiety, depression, and chronic pain.”
Even Parkinson’s Disease has been linked to gut bacteria in studies performed by microbiologist Sarkis Mazmanian, who points out that “70 percent of all neurons in the peripheral nervous system—that is, not the brain or spinal cord—are in the intestines, and the gut’s nervous system is directly connected to the central nervous system through the vagus nerve.” Our guts also supply the brain with fuel, and it requires a “constant supply,” notes Dr. Eva Selhub at the Harvard Health Blog. “That ‘fuel’ comes from the foods you eat—and what’s in that fuel makes all the difference. Put simply, what you eat directly affects the structure and function of your brain and, ultimately, your mood.”
Such findings have given rise to the emerging field of Nutritional Psychiatry, which you can hear described in the TEDx talk above by clinical psychologist Julia Rucklidge. Initially taught that “nutrition and diet were of trivial significance for mental health,” Rucklidge, like most of her colleagues, believed that “only drugs and psychotherapy could treat these serious conditions.” But after encountering evidence to the contrary, she decided to do her own studies. Beginning at around 5:30, she presents compelling evidence for a dramatic reduction in rates of ADHD, PTSD, depression, and psychosis after dietary treatments.
That’s not to say that drugs and psychotherapy do not play important roles in treatment, nor that they should be supplanted by a nutrition-only approach. But it does mean that nutritional treatments are shown by many fields of study to be effective and perhaps essential, for reasons consistent with widespread knowledge about the body and brain. “It is now known,” for example, as Joyce Cavaye reports at the Independent, “that many mental health conditions are caused by inflammation in the brain which ultimately causes our brain cells to die.” Inflammation is, in part, caused by “a lack of nutrients such as magnesium, omega‑3 fatty acids, probiotics, vitamins and minerals… all essential for the optimum functioning of our bodies.”
Diets consisting primarily of highly processed foods and sugars are also a cause of inflammation. “Multiple studies have found a correlation between a diet high in refined sugars and impaired brain function,” Dr. Selhub writes. These diets promote a “worsening of symptoms of mood disorders, such as depression.” Processed foods with high carbohydrate content and few nutrients have created an epidemic of malnutrition among a significant portion of the population who otherwise seem to have plenty to eat. The situation seems to have majorly contributed to the corresponding epidemics of depression and other mental health conditions.
Nutritional psychiatry is not a fad or a program claiming to recreate the diet of early humans. While “a potential evolutionary mismatch between our ancestral past (Paleolithic, Neolithic) and the contemporary nutritional environment” merits exploration, as researchers write in an article published at the Journal of Physiological Anthropology, many more contemporary factors—such as economic development and the rise of scientific medicine—play a role in how we understand diet and mental health.
Rather than look to prehistory, scientists have studied the diets of “traditional” societies (those not reliant on mass-produced processed foods) in the Mediterranean and Japan. They have found a 25–35% lower rate of depression, for example, in those who eat diets “high in vegetables, fruits, unprocessed grains, and fish and seafood,” writes Selhub, with “only modest amounts of lean meats and dairy.” There is no perfect dietary formula, however. Everyone’s gut processes things differently. Dr. Selhub recommends cutting out processed foods and sugar and experimenting with adding and subtracting foods to see how you feel. (Nutritional experiments like these are probably best carried out after consulting with your doctor.)
Just as we will need to change the way we eat if we want to preserve our outer environment, the health of that rich, and no less necessary, inner world known as the microbiome will require what for many is a dramatic change in eating habits. Sadly, it is not a change everyone can afford to make. But for millions suffering from mental illnesses, nutritional psychiatry may represent a life-altering course of treatment.