Nutrition Psychiatry: How Food Impacts Mental Health


The chemical messengers in your brain have to made of something, which means food is absolutely a contributor to the state of your mental health.

Food is for physical wellness, and pharmaceutical products are for mental health conditions—that’s where most of us land when it comes to nutrition psychiatry.

Somehow, we’ve been trained to believe that the only way to bridge the gap between the tangible, easily measurable world of physical wellness and the much more elusive domain of mental health is with expensively marketed pharmaceutical products.

But vitamins, minerals, probiotics, phytochemicals, and other compounds that can help people with mental health disorders don’t care about how they’re packaged; they will do what they do regardless of what they’re called or how much they cost.

Researchers are quietly removing this needlessly drawn line in the sand with objective proof that food can help with depression, anxiety, ADHD, and other highly common mental health disorders.

Here’s what they had to say. 

Probiotics, Vitamin D, and Depression

To be clear, serotonin and depression are not as strongly connected as many claim, and the overall pathology of depression is much more complicated than a singular “chemical imbalance,” but serotonin is still believed to play an important role in the progression or prevention of the disorder.

Eva Selhub, MD, contributor to the Harvard Health Blog, had an eye-opening insight to share relating to the body’s production of serotonin in this post: “Since about 95% of your serotonin is produced in your gastrointestinal tract, and your gastrointestinal tract is lined with a hundred million nerve cells, or neurons, it makes sense that the inner workings of your digestive system don’t just help you digest food, but also guide your emotions.” 

Dr. Selhub then explained that the health and functional capacity of these serotonin-promoting neurons is a direct product of the condition of the “billions of good bacteria that make up your intestinal microbiome.”

These are the bacteria you’re replacing when you consume probiotic-rich foods (and the kind you’re “feeding” when you consume prebiotic-rich foods). 

Put simply, keeping the billions of benevolent bacteria in your stomach well-fed and well-populated will promote the health of neurons in the intestinal tract, which will give you the best chance at maximizing serotonin production.

A Note on Vitamin D

Perhaps a slightly more well known connection between nutrition and depression is the vitamin D factor.

In this review of more than a dozen studies, researchers from St. Joseph’s Hospital in Ontario, Canada concluded that “Lower vitamin D levels were found in people with depression compared to controls…and there was an increased odds ratio of depression for the lowest v. highest vitamin D categories in the cross-sectional studies.” 

In this particular finding and so many others focused on the same correlation, researchers have called for controlled trials and evidence-based reviews to tease out the specific mechanisms involved.

Thankfully, essential vitamin D is obviously safe when consumed within appropriate ranges, so vitamin-D-deficient consumers with or without depression don’t have to wait for these more deeply layered insights to emerge. 

Anxiety Research Points to Traditional Nutrition

When Scottish surgeon James Lind discovered that citrus fruit juice could treat scurvy, a nutritional deficiency that plagued sailors of past centuries, he may have also stumbled upon a nutritional defense against anxiety. 

In the mid-18th century, Lind discovered in a very early iteration of the “modern” clinical trial that seafaring men affected by scurvy could be nursed back to health by consuming oranges and lemons.

Other than the severe skin lesions, equally severe gum decay, and other physical manifestations of scurvy, many of the affected sailors monitored in Lind’s trial (on the HMS Salisbury in 1747) reportedly demonstrated anxiety and depression symptoms.

Sure enough, lemons and oranges far outperformed the other interventions tested in the trial (who would have thought “half a pint of sea water a day” wouldn’t have done the trick?), severely reducing all symptoms, anxiety included.

This isn’t to say that all instances of anxiety or depression can be significantly improved by citrus fruits, because scurvy involves a few mechanisms not affecting the everyday anxiety sufferer, but it’s a connection that is still too important to ignore. 

Traditional vs. Western Dieting

Sadly, but not surprisingly, it’s time for the next episode of “Why the American Diet Is Terrible,” this time focusing on the influence of processed and refined foods on mental health.

In this study from Australia’s University of Melbourne, researchers assessed the dietary patterns as well as the severity and prevalence of anxiety symptoms among 1,046 women in order to observe any connections between these two factors. 

Upon discussing their findings, the researchers explained that “A ‘western’ diet of processed or fried foods, refined grains, sugary products, and beer was associated with a higher GHQ-12 (anxiety symptom measurement tool) score.” 

Conversely, a “traditional” diet that emphasized minimally processed vegetables, fruit, lean protein, and whole grains was associated with a significantly lower average score on the anxiety measurement tool.

While this certainly doesn’t narrow down any single nutrient as a natural defense against anxiety, it does echo a very important and obvious theme: the more balanced and healthy your diet is, the less you need to worry about which foods cause which diseases (because you’re not eating them in the first place). 

Trace Minerals Tagged as Potential ADHD Mediators

However contentious the modern medical establishment’s approach to ADHD—not to mention, the actual cause of the disorder—may still be, researchers have soldiered on for decades in the effort to find non-pharmaceutical influences on the disorder.

A particularly eye-opening study out of the University of British Columbia in Canada found that children with ADHD typically consumed significantly lower quantities of zinc and copper than “local population norms.”

This may seem like a trivial mention at first, but as the researchers noted, “The importance of these findings is that zinc, iron, and copper are essential cofactors in the production of dopamine and norepinephrine; two neurotransmitters critical in the etiology of ADHD.”

The relationship here is not so different from the abovementioned 3-step connection between probiotics and depression; zinc and copper help dopamine and norepinephrine production, which in turn are believed to prevent the development of ADHD.

For reference, here’s a list of foods containing zinc and/or copper:

  • Crab (zinc)
  • Pork chops (zinc)
  • Baked beans (zinc)
  • Yogurt (zinc)
  • Swiss cheese (zinc)
  • Almonds (zinc)
  • Peas (zinc)
  • Oysters (zinc/copper)
  • Beef (copper)
  • Potatoes (copper)
  • Mushrooms (copper)
  • Turkey (copper)
  • Chickpeas (copper)
  • Avocado (copper)
  • Tomatoes (copper)

Expectation Management for Nutrition Psychiatry Newbies

Nutrition is just one of many factors influencing mental health, and as such, is unlikely to completely reverse more serious mental health challenges.

However, it still holds great potential as both a preventive and post-diagnosis “treatment.”

In every conceivable case, the nutritional changes required to address mental health concerns work in service of physical health as well.

In other words, you stand to benefit in every way from simply making changes in your nutritional habits, and with extremely low risk.

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