Psience Quest

Quote:Earlier studies suggest what you might expect: eating junk isn’t great for your brain. People who consume plenty of fruit, vegetables, and fish seem to be less at risk of depression compared to those who favor fatty meats, processed carbs, and sweets. But emerging research shows that even among healthy diets, some might be better for mental health than others. In a recent review published in Molecular Psychology, researchers analyzed 41 studies that sought to quantify the impact of various diets on clinical depression. The analysis accounted for a variety of eating plans including the Mediterranean diet, the DASH diet, and the Healthy Eating Index.

The winner? The Mediterranean diet, which according to the American Journal of Clinical Nutrition features abundant fruits and vegetables, olive oil, dairy products like yogurt and cheese, cereals, beans, fish and poultry, and moderate amounts of red meat and wine. (Sometimes it seems to be the best diet for just about everything: it may help you live longer, and it recently won the top spot in an exhaustive, expert-led analysis of 40 diets based on metrics like being heart-healthy, plant heavy, and easy to adhere to.)

Drew Ramsey, an associate professor of psychiatry at Columbia University and the author of Eat Complete, says the Mediterranean diet may have a positive effect on mental health because it helps fight inflammation. “Molecules that are responsible for inflammation influence things like your mood and energy levels,” says Ramsey. “For example, inflammation gets in the way of the brain’s self-repair process. Many antidepressant medications are also powerful anti-inflammatories that spur brain growth.” The diet may also improve your gut microbiome, which research suggests influences depression.

But don’t purge your refrigerator or medicine cabinet quite yet. Observational nutrition studies, where researchers ask participants to recall their eating patterns, can be unreliable, says Trevor Kashey, an Ohio-based registered dietitian. “People lie, don’t know how to track their intake, and have terrible memories,” he says.

Quote:A randomized controlled trial published in the journal PLOS ONE finds that symptoms of depression dropped significantly among a group of young adults after they followed a Mediterranean-style pattern of eating for three weeks. Participants saw their depression "score" fall from the "moderate" range down to the "normal" range, and they reported lower levels of anxiety and stress too.

Alternatively, the depression scores among the control group of participants — who didn't change their diets — didn't budge. These participants continued to eat a diet higher in refined carbohydrates, processed foods and sugary foods and beverages. Their depression scores remained in the "moderate severity" range.

"We were quite surprised by the findings," researcher Heather Francis, a lecturer in clinical neuropsychology at Macquarie University in Sydney, Australia, told NPR via email. "I think the next step is to demonstrate the physiological mechanism underlying how diet can improve depression symptoms," Francis said.

Quote:Groups of researchers believe they are on the cusp of a revolution that uses "mood microbes" or "psychobiotics" to improve mental health.

The study that ignited the whole concept took place at Kyushu University in Japan.

The researchers showed that "germ-free" mice - those that never came into contact with microbes - pumped out twice the amount of stress hormone when distressed than normal mice.

The animals were identical except for their microbes. It was a strong hint that the difference was a result of their micro-organisms.

"We all go back to that first paper for the first wave of neuroscientists considering microbes," says Dr Jane Foster, a neuropsychiatrist at McMaster University in Canada.

"That really was very powerful for those of us who were studying depression and anxiety."