The study, which examined data from 3,654 U.S. adults aged 20 and older between 2011 and 2016, reported that sufficient levels of vitamin D, iron, selenium, copper, and vitamin B6 were associated with 25% to 52% lower odds of self-reported depressive symptoms. The researchers adjusted for age, sex, smoking status, physical activity, food security, and income, according to the report.
Study Design and Methods
Researchers analyzed data from NHANES, a nationally representative survey conducted by the Centers for Disease Control and Prevention (CDC). Participants had an average age of 44 years.
Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9), a standard screening tool.
Blood levels of vitamin D and iron were measured directly, while dietary intake of selenium, copper, and vitamin B6 was estimated from 24-hour dietary recalls, the study authors stated. The analysis controlled for multiple potential confounders, including socioeconomic factors and health behaviors, to isolate the associations between nutrient status and depressive symptoms.
Individual Nutrient Findings
Vitamin D showed a clear association: participants with sufficient blood levels had 25% lower odds of depressive symptoms compared to those with insufficient levels, according to the researchers.
Vitamin D acts as a hormone involved in neurotransmitter production and brain cell signaling, and receptors for it are found in mood-regulating brain regions such as the hippocampus, the study noted.
Iron presented a similar pattern. Adults with normal iron levels were 26% less likely to report depressive symptoms.
Iron supports the production of neurotransmitters like serotonin, dopamine, and norepinephrine, and is essential for oxygen transport and energy production in the brain, the researchers explained.
Selenium had the strongest association among the nutrients studied. Participants who met dietary intake recommendations had 52% lower odds of depressive symptoms.
Selenium is a trace mineral critical for antioxidant defense, particularly in activating glutathione, which protects brain cells from oxidative stress, according to the report.
Copper was linked to 34% lower odds of depressive symptoms among those with adequate intake. Copper helps activate antioxidant enzymes and supports nervous system function, although prior studies on blood copper levels have shown mixed results, the researchers noted.
Vitamin B6, required for the synthesis of mood-regulating neurotransmitters including serotonin, dopamine, and GABA, was associated with 27% lower odds of depressive symptoms.
The researchers also highlighted a potential synergistic relationship between vitamin B6 and magnesium in supporting nervous system health, as vitamin B6 plays a direct role in neurotransmitter synthesis [1].
Limitations and Expert Commentary
The researchers cautioned that the findings do not establish that micronutrient deficiencies cause depression. The cross-sectional design of the study means it can only identify associations, not causation, and prior research on supplementation for depression has yielded mixed results, according to the study authors.
Nutrition scientist Dr. Alan Logan, author of "The Brain Diet," noted in a statement that the study adds to a growing body of evidence linking diet quality to mental health but urged caution in interpreting odds ratios from cross-sectional data.
The study relied on self-reported dietary intake and a single blood draw, which may not reflect long-term nutrient status, a limitation acknowledged by the researchers.
Additionally, while some supplements have shown benefit in clinical trials, the evidence remains inconsistent. For example, supplements such as St. John's wort have shown relief from mild depressive symptoms, and some studies have found that adding nutritional supplements to antidepressant regimens can improve outcomes [2] [3].
However, the current study did not test supplementation and focused solely on nutrient adequacy from diet and blood levels.
Implications and Recommendations
The study suggests that maintaining adequate levels of these micronutrients may support brain function and mood regulation. The researchers emphasized that a balanced diet rich in whole foods is a practical approach to achieving nutrient sufficiency, without making specific supplementation recommendations.
Food sources for the identified nutrients include Brazil nuts for selenium, chickpeas, poultry, and salmon for vitamin B6, fatty fish and sunshine exposure for vitamin D, and organ meats, spinach, and legumes for iron and copper. The study adds to a growing body of research confirming that what you eat directly shapes mood and mental health [4].
Deficiencies in key micronutrients like magnesium, zinc, B vitamins, and vitamin D are common and can exacerbate mental health issues [5].
The researchers called for further research, including longitudinal and intervention studies, to clarify the causal relationships between micronutrient status and depression.
References
- Dr Alan Logan. "The Brain Diet The Connection Between Nutrition Mental Health and Intelligence".
- Mercola.com. "Supplements Proven Beneficial for Depression". July 14, 2016.
- Mercola.com. "1 in 6 Americans Are Now on Psychiatric Medic". December 29, 2016.
- Willow Tohi. "New research confirms What you eat directly shapes your mood and mental health". NaturalNews.com. March 12, 2026.
- NaturalNews.com. "New research confirms: What you eat directly shapes your mood and mental health". March 12, 2026.
- 5 Vitamins & Minerals That Are Linked to Fewer Depressive Symptoms. mindbodygreen.com. Molly Knudsen. May 26, 2026.
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