Telling people to eat their way to a different outlook is nothing new. Think of religious fasting. Or John Harvey Kellogg’s anti-masturbation cornflake diet. In 17th-century England, a “hot and moist diet” was even thought to provide a cure for melancholy. Today, the idea that food can have an impact on emotional health hasn’t gone away; it just looks a little different. The internet is littered with food-based mental-health fixes, ranging from books with titles like The Happiness Diet to recipes for things like “better than Prozac” turmeric lemonade.
To be clear, plenty of these current-day claims are goofy at best, dangerous at worst. The evidence shows antidepressants are effective at treating depression; lemonade, turmeric or no, isn’t going to have the same effect. But the growing field of nutritional psychiatry is making the case that food and medicine don’t have to represent two distinct paths to mental health — that, in fact, diet can play a significant role in comprehensive mental-health treatment.
Mark Haub, a professor of nutrition at Kansas State University, describes nutritional psychiatry as a field where both mental health and nutrition professionals can “cross over and better understand how food and nutrients can affect mental health and mental status.” In particular, a body of research has emerged in the last decade linking healthy diet with the treatment and prevention of depression. (The particular definition of healthy diet vary from study to study, but generally speaking, the common link is nutrient-dense plant based foods and lean proteins — in other words, cornflakes and turmeric lemonade need not apply.)
“We know there’s a link between food and mental health and mental status, especially depression,” he says. While there isn’t enough evidence yet to recommend a change in patient care for patients suffering from depression, these initial studies do offer support for the idea of reducing the risk of depression with a healthy diet. Some very preliminary studies suggest that diet may be successful as an intervention to treat depression as well.
There are some caveats to keep in mind: Most of the studies were observational, rather than the scientific gold standard of randomized trials. And in one well-designed study that found a healthy diet to be effective at preventing depressive episodes, most of the patients were already taking medication as well.
Still, Haub believes there’s no question that, in the future, nutritional psychiatry will play an important role in the prevention and treatment of depression — though it will take a lot of weeding out false claims for the practice to gain a legitimate standing. “If it’s too good to be true, it’s too good to be true,” he says, “so always be skeptical of [anyone who says], ‘Take this supplement, it’s going to cure depression’ … [or that] they know what works for everybody.”
Nutritional psychiatry researchers also have to contend with the fact that humans are notoriously unreliable subjects. In a recent review paper titled “Nutritional Psychiatry: Where to Next?,” the authors noted, “Ensuring and accurately measuring dietary adherence is far more challenging in nutrition than in almost any other field of research.” Haub notes that researchers are beginning to grasp that there will always be exceptions — people for whom a dietary change didn’t have the same impact, whether because of genetic differences or environmental ones.
Ideological bias is a problem too, according to Haub: “The other concern I have with the lifestyle sciences [is] if you have a person who thinks low-carb diets are the way to go, they’ll probably have data that shows low carb reduces depression” more than, say, low-fat diets. “And that’s a problem within our profession: I think we have fewer scientists and more health promotion experts, and we need more scientists. Let the clinicians deal with what they think will be best for their clients and let the scientists stick to data.” And in time, that data should begin to offer more guidance on the link between what we put in our mouths and what’s happening in our brains.