Diet and Anxiety: Magnesium Deficiency and Nutrition in Mental Health

By May 2024, Ebony Dupas felt a problem she could not ignore: a mild anxiety about direction and purpose that soon spiraled into paranoia she could not shake. Referred by her doctor, she saw several psychiatrists who considered generalized anxiety disorder, bipolar disorder, or schizophrenia, and most urged medication right away. One clinician ordered bloodwork first, hoping to rule out hidden causes. “I was mostly depleted of magnesium,” Dupas says. That discovery opened a broader conversation about nutrition's role in mental health, a field drawing increasing attention as researchers map how the gut and micronutrients influence mood and cognition.

Researchers have found links between the gut microbiome and mental health, and between deficiencies in micronutrients like magnesium and choline and conditions such as anxiety and depression. Yet robust clinical trial data remain limited, and many dietary supplements reach the market with little FDA oversight, complicating decisions for patients and clinicians. As Uma Naidoo, director of nutritional and lifestyle psychiatry at Massachusetts General Hospital, notes, the link between food and the brain is often overlooked. “The brain and mental health are no longer just 'above the neck' problems,” Naidoo says.

The most understood link involves how diet shapes the gut microbiome. The gut produces most of the body’s serotonin, as well as a large share of the neurotransmitter GABA. Drugs that alter serotonin levels are commonly used to treat depression and anxiety, with SSRIs among the most prescribed. Beyond gut health, there’s growing interest in how specific vitamins and minerals affect the brain. Deficiencies in several micronutrients, including magnesium, B vitamins, vitamin D, omega-3s, choline, and L-theanine, have been linked to mood and anxiety in various studies. However, the research in humans is still mixed, and many studies struggle with varying supplement formulations and dosages. A 2024 review found supplemental magnesium is likely useful in treating mild anxiety and insomnia, especially in people who already have low magnesium, but results across studies are inconsistent, in part due to the many different magnesium forms—such as citrate, malate, glycinate, oxide, and chloride—and how well the body can absorb them. “How well the body can make use of magnesium in these different forms still needs to be better studied,” says Alexander Rawji, a psychiatrist and co-author of the review. Similar challenges exist for other micronutrients.

As high school biology taught, eating a varied diet rich in vitamins and minerals is crucial because the body cannot manufacture these nutrients and relies on intake to perform essential functions. National survey data have suggested large gaps: as much as 94 percent of the U.S. population does not get adequate daily vitamin D, 52 percent don’t get enough magnesium, and 92 percent don’t get enough choline. While the link between nutrition and brain health is clear, it remains premature to prescribe universal dietary or supplement strategies for mental illness. Ideally, researchers will one day clarify exactly how micronutrients in the diet affect brain function, determine which supplements are best absorbed, and identify which patients might benefit most from nutritional interventions.

Dupas’ blood work led to a regimen that included magnesium, L-theanine, B-complex vitamins, and omega-3s in addition to a small SSRI. After a couple of weeks, she says, she felt “really clear again” and could focus without the gnawing paranoia. She acknowledges that she may be among a minority who respond to supplementation in this way, but she hopes more patients receive a similar test-and-treat approach. Experts caution that supplementation should not replace established treatments, and results will vary from person to person. Blood tests can also fail to reveal total body magnesium stores, even when serum levels appear normal. Rawji notes that doctors who use supplements typically view them as part of a multipronged strategy, rather than a substitute for medications or psychotherapy. “If you expect magnesium to be a benzo for anxiety, then you’re going to be very disappointed,” he says.

Not all psychiatrists routinely inquire about diet or nutrition deficiencies when evaluating patients, and this can lead to missed opportunities for simple, low-risk interventions. Naidoo emphasizes that while supplements carry risks if misused, a healthy, balanced diet often provides adequate nutrients. For patients seeking to improve micronutrient intake, she suggests focusing on whole foods: green leafy vegetables for magnesium; milk, eggs, and whole grains for B vitamins; eggs, beans, and cruciferous vegetables for choline; fatty fish and eggs for vitamin D; and green tea as a source of L-theanine. Nutrition, Naidoo says, is a powerful tool for overall health, and its potential benefits for the brain are increasingly recognized.

The case underscores a broader shift in thinking about mental health care. While science has not established a one-size-fits-all role for micronutrients in treating anxiety or mood disorders, clinicians are paying closer attention to nutritional status as part of comprehensive care. As research progresses, doctors hope to better determine who may benefit from bloodwork and targeted supplementation, and how to integrate dietary strategies with psychotherapy and pharmacotherapy to support patients’ mental health.