Diet tips aren’t something you’d traditionally seek out from a therapist, but some providers are starting to offer nutritional advice as part of their counseling. The young field of nutritional psychology (or nutritional psychiatry — the terms are used interchangeably) is a new addition to “lifestyle medicine,“ a movement that advocates for behavioral changes to play a central role in improving patient health outcomes and managing illness. 

The theory behind nutritional psychology is simple: Dietary changes, such as cutting back on processed foods and loading up on seafood for its omega-3 fatty acids, can have a measurable impact on mental health.

Yet despite early, intriguing research on the diet-psychology connection, this emerging field lacks important safeguards, such as standardized treatment protocols or formal training requirements — or regulations of any kind. That’s reason enough, experts say, to take a good, skeptical look at anyone who calls themselves a nutritional psychologist before signing up for their take on yesterday’s breakfast.  

Diet and mental health: what we know

About a decade ago, an Australian research team found the first hints of a connection between diet and common mental disorders such as depression and anxiety. Previous studies had examined how consuming individual foods or nutrients affects mental health. But Felice Jacka, a professor of nutritional and epidemiological psychiatry at Deakin University in Australia, wanted to see if daily eating habits had a meaningful relationship to mental health. So Jacka and her colleagues tracked diet patterns and symptoms of common mental disorders in a group of more than 1,000 women over a 10-year period. They found a clear link between diet quality and depression.

Jacka’s team uncovered the same link in teenagers and Norwegian adults soon afterwards. Then, in a 2017 clinical trial, they found that participants with major depressive disorder who received personalized dietary advice and nutritional counseling reported significantly reduced depressive symptoms. These study participants had modified their diets by loading up on produce, whole grains, legumes and lean protein, and cutting down on sugary and processed foods. “This showed you could help people with clinical depression to make simple, feasible, inexpensive changes to their diets that had a substantial impact on their symptoms,” says Jacka, who is also president of the International Society for Nutritional Psychiatry Research and director of the Food and Mood Centre in Australia.

Most recently, Jacka’s team performed a meta-analysis of 16 clinical nutrition trials, to see if any associations between healthy eating and mental health bore out across a larger pool of research. Dietary changes reduced depressive symptoms, they found, but appeared to have no measurable effect on anxiety.

Other experts are building on Jacka’s work: A different Australian team ran a follow-up study based on her 2017 trial, and published the results this summer. They found that a Mediterranean diet supplemented with fish oil reduced depression symptoms substantially. At this point, a Mediterranean diet is the only kind whose benefits for depression are supported by research.

Despite repeated evidence of a link between food and mental health, the exact nature of the link remains unclear. Experts believe a few factors may be at play. First, some foods might promote inflammation (the immune system’s response to invaders), which is a risk factor for depression. 

Second, “mental health depends on brain health, and brain health depends on food,” says Dr. Drew Ramsey, a psychiatrist and professor at Columbia University. “If you’re missing certain nutrients, such as vitamin B12, iron and omega-3 fatty acids, you will get depressed.” Studies also show that dietary changes can affect the size of the hippocampus, the brain region that’s in charge of memory and learning and is most closely associated with psychiatric disorders. 

Finally, what we eat affects which types of bacteria live in our guts, which matters because our microbiota might influence our mental health. When scientists transplant fecal matter from humans with schizophrenia or depression into rodents, the animals exhibit behaviors like those of the source humans. Though findings are still inconclusive, other research indicates that probiotics might help those with depression and anxiety.

Nutritional psychology in practice

“[It’s] common sense to pay attention to lifestyle factors” when it comes to mental health, Ramsey says. “What you eat and how much you exercise is critical in getting better from depression and staying better. But it hasn’t been the focus of treatment plans across mental healthcare generally.” 

In his clinic, in addition to a general psychiatric evaluation, Ramsey assesses the content of a patient’s diet, their relationship with food and their level of motivation to make any dietary changes. He then offers concrete strategies to increase intake of healthy foods (primarily plant-based and seafood), replace highly processed foods with healthier options and decrease snacking overall. Others might recommend adding supplements, removing certain foods or going on specific diets. 

That said, since the discipline is unregulated, it’s hard to predict how a nutritional psychologist will approach treatment. There’s no national certification program; experts are more or less self-designated, much like health coaches were until this summer.

“I am passionate about dietary interventions being a possible treatment for psychiatric disorders, including really severe disorders like schizophrenia and bipolar disorder,” says Dr. Chris Palmer, assistant professor of psychiatry at Harvard Medical School and director of the department of postgraduate and continuing education at McLean Hospital. “But right now, ‘nutritional psychologist means a million different things. You have no idea what you are going to get.”

“If we don’t get more rigorous and scientific about this, this field will never advance,” Palmer says. 

With a little googling, you can find the Institute for the Psychology of Eating, which certifies students as “mind body eating coaches”; two universities offering certifications in nutritional psychology; a nine-month online course to become a nutritional therapy consultant; and a six-hour online course in nutritional psychiatry. Some require a certificate or license in nutrition or dietetics; others are open to anyone. 

That means people who call themselves nutritional psychologists might not be licensed as either mental healthcare providers or nutritionists. A practitioner could recommend a diet simply because they think ketogenic is the best or gluten is the devil. They could even sell a patient supplements for profit.

“I’m not against supplements, but as an ethical practitioner, I will tell my patients where to go and buy them so there is no conflict of interest, says registered dietitian nutritionist Angela Lemond, spokesperson for the Academy of Nutrition and Dietetics.

A title as official-sounding as “nutritional psychologist” could also give the false impression that eating wild salmon and kale will resolve your condition, Ramsey says. “Mental health disorders are really personal and really complex,” he adds. “This is not meant to be a replacement for other treatments,” such as therapy and medication, but instead is meant to be used in conjunction with those things.

Your health comes first

While exciting, nutritional psychology is still very young. Some leaders in the field are calling for regulation and standardization of care. Jacka and her colleagues at the Food and Mood Centre are working with an international team of experts to develop clinical guidelines for practitioners on how to use lifestyle changes as the foundation for treating mental disorders.

In the meantime, for anyone interested in using nutrition to support mental health, most experts recommend seeing both a mental health professional and a dietitian. There are also practical benefits of seeking out licensed providers. While insurance should cover mental healthcare and nutritional care, services furnished by a nutritional therapist might not make the cut. 

No matter who you see, check out their education and experience, and ask not only what type of care they provide but also what evidence they have that their treatment method works. And don’t neglect other forms of care. “This alone is not going to cure you,” Palmer adds. “This is one part of a comprehensive treatment plan. So many factors go into mental health, and diet and dietary interventions can be part of that.”

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