Depression remains one of the most common and disabling mental health conditions worldwide. While evidence-based psychotherapy and prescription antidepressants form the foundation of care, a growing body of high-quality research shows that certain nutritional supplements can offer meaningful benefits—particularly when used as add-ons to standard treatment or in mild-to-moderate cases.
Recent large-scale systematic reviews and network meta-analyses have clarified which supplements have the strongest scientific support.
Omega-3 fatty acids, especially formulations rich in eicosapentaenoic acid (EPA), consistently rank among the most effective. Multiple meta-analyses demonstrate modestto-moderate reductions in depressive symptoms, with clearer benefits when EPA is emphasized over DHA and when used alongside antidepressants. Typical effective doses in studies fall in the range of 1–2 grams of EPA daily. These fatty acids appear to work partly through anti-inflammatory pathways and support of neuronal membrane function.
Vitamin D supplementation also shows benefit, particularly in people with low baseline levels or existing depressive symptoms. A 2024 dose-response meta-analysis of randomized trials found that vitamin D3 produced small-to-moderate improvements in depressive symptoms, with stronger effects at higher daily doses (up to around 8,000 IU in short-term studies) and in trials lasting up to 24 weeks. Checking blood levels before starting is advisable.
S-adenosylmethionine (SAMe) has demonstrated efficacy both as monotherapy and as an adjunct in several reviews. It participates in methylation reactions important for neurotransmitter synthesis. Evidence supports moderate symptom reduction compared with placebo, with generally good tolerability, though quality and dosing (commonly several hundred milligrams daily) matter.
Zinc supplementation has shown promise, especially as an add-on to antidepressants. Network analyses highlight notable effect sizes for zinc combined with standard medication, and observational data link lower zinc status with higher depression risk. Doses around 25 mg elemental zinc have been studied.
Other agents with supportive but somewhat more mixed or emerging data include saffron extract, curcumin, and, in limited recent reviews, creatine. St. John’s wort has longstanding evidence of effectiveness comparable to certain antidepressants for mild-to-moderate depression; however, it carries a high risk of clinically significant drug interactions (including with antidepressants, oral contraceptives, and many other medications) and should only be considered under medical supervision with standardized preparations
Important caveats apply. These supplements are not replacements for professional evaluation, therapy, or prescribed medication. Quality, purity, and dosing vary widely among commercial products. Some (notably SAMe and St. John’s wort) can trigger mania or hypomania in people with bipolar spectrum conditions. Interactions, medical comorbidities, and pregnancy status must be reviewed with a clinician. Benefits tend to be largest as adjunctive strategies rather than sole treatments for moderate-to-severe depression.
The science continues to evolve, but current evidence from network meta-analyses and dose-response reviews supports selective use of omega-3s (EPA-focused), vitamin D (when deficient), SAMe, and zinc as reasonable, relatively low-risk options for many patients seeking additional support.
References
Cheng, Y.-C., Huang, W.-L., Chen, W.-Y., Huang, Y.-C., Kuo, P.-H., & Tu, Y.-K. (2025). Comparative efficacy and tolerability of nutraceuticals for depressive disorder: A systematic review and network meta-analysis. Psychological Medicine, 55, e134. https://doi.org/10.1017/S0033291725000996
Ghaemi, S., Zeraattalab-Motlagh, S., Jayedi, A., & Shab-Bidar, S. (2024). The effect of vitamin D supplementation on depression: A systematic review and dose–response metaanalysis of randomized controlled trials. Psychological Medicine, 54(15), 3999–4008. https://doi.org/10.1017/S0033291724001697
National Center for Complementary and Integrative Health. (n.d.). St. John’s wort: Usefulness and safety. U.S. Department of Health and Human Services. https://www.nccih.nih.gov/health/st-johns-wort
Sarris, J., et al. (relevant guideline syntheses and earlier foundational reviews informing current practice, including World Federation of Societies of Biological Psychiatry / CANMAT recommendations on omega-3, methylfolate, SAMe, zinc, and vitamin D).
Additional supporting meta-analyses on omega-3 (EPA-focused formulations), SAMe monotherapy, zinc adjunctive use, and emerging creatine data published 2024–2026 in journals including BJPsych Open, Progress in Neuro-Psychopharmacology and Biological Psychiatry, British Journal of Nutrition, and The Canadian Journal of Psychiatry.