Food May Be a Tool to Consider When Helping Psychiatric Patients

Columbia University

The notion that “food is medicine” dates to Hippocrates. There is an increasing base of evidence demonstrating that diet choice is strongly correlated with mental health risk, particularly the risk of depression, dementia, and attention-deficit/hyperactivity disorder. It is also a tool to consider in helping psychiatric patients achieve full recovery. From the building blocks of neurons to influencing the expression of BDNF to dictating the microbiome, the research suggests that food is brain medicine.

Multiple studies show that dietary pattern is clearly correlated with depression and dementia. A large prospective trial in Spain followed healthy university students for 4.4 years. They reported a 42 percent decreased risk of major depression for those who most closely adhered to a Mediterranean diet. Conversely, consumption of high glycemic index foods increased the risk of depression in postmenopausal women, as does a “Western” dietary pattern composed of simple carbohydrates, fried foods, and highly processed foods.

A number of such epidemiological studies are supported by the results of recent clinical trials. Stahl and colleagues found that elderly patients who had received six to eight dietary counseling sessions showed a decrease in Beck Depression Inventory ratings (9.9 to 5.9). This was sustained for the two years of the study. In a randomized trial of 243 individuals comparing a Mediterranean diet supplemented with extra nuts versus extra olive oil, those receiving nuts had a decreased risk of low levels of plasma BDNF after three years (odds ratio 0.22). Additional studies also suggest that diet impacts brain size. For instance, a study that followed 255 individuals aged 60 to 64 over four years and measured MRI changes found that left hippocampal volume was significantly smaller in individuals who ate a Western diet.

The mechanism underlying the effects of food on brain health and psychiatric illness include the influence of food choice on the methylation cycle, inflammatory factors, the microbiome, and neuroplasticity. Several nutrients such as zinc, magnesium, and the omega-3 fats influence neuroplasticity by promoting the expression of BDNF, as do a number of flavonol phytonutrients.

While nutrition is not a focus of psychiatric assessment or training, the lessons of a few key foods—kale, mussels, and dark chocolate—cover the basics of “psychofarmacology.”

Kale and other dark leafy greens teach the rule of nutrient density: a cup of raw kale delivers 608 percent of the recommended daily allowance (RDA) of vitamin K, 206 percent of vitamin A, 134 percent of vitamin C, more iron per calorie than beef, and a form of calcium that is more absorbable than that in milk—all for 33 calories. Additionally, in the era of the microbiome, eating plants plays a key role in regulating gut health and determining the microflora.

Mussels and other bivalves illustrate the importance of seafood. They offer an excellent source of long-chained omega-3 fats, vitamin B12, and numerous minerals. At only 57 calories, six oysters deliver 509 percent of the RDA for zinc, 272 percent of vitamin B12, and 522 mg combined EPA/DPA/DHA, and one-third of the RDA of iron, selenium, and vitamin D.

Research suggests that even some desserts, in moderation, can offer benefits for the brain. A study by Scott Small, M.D., of Columbia University and colleagues found that adults who consumed a high-cocoa flavanol drink daily for three months demonstrated improvements in the function of the dentate gyrus and on a memory task. This should not be taken as license to justify eating vast quantities of dark chocolate, as moderation is still a key rule of healthy consumption.

In addition to being relatively low risk, prescribing food presents an opportunity for psychiatrists to engage patients in self-care by helping them better nourish their brains. ■