Depression

5-HTP is a direct precursor to serotonin and crosses the blood-brain barrier, bypassing the rate-limiting tryptophan hydroxylase step. Multiple double-blind, placebo-controlled trials support its efficacy in mild-to-moderate depression. A meta-analysis of over 500 participants found 5-HTP significantly more effective than placebo with effect sizes comparable to conventional antidepressants.

Antidepressant activity has been documented in preclinical in vivo studies of A. spectabilis and is confirmed in pharmacological reviews. The despair swim test (forced swim test), a standard rodent antidepressant model, was among the assays used in testing Abies extracts.

Acetyl-L-Carnitine (ALC) deficiency has been implicated in depression, particularly in older adults. A systematic review and meta-analysis confirmed antidepressant efficacy (SMD = −1.10, 95% CI −1.65 to −0.56) and a 2017 meta-analysis found ALC significantly reduced depressive symptoms. It modulates glutamate transmission, epigenetic methylation, and neurotrophic factor expression.

Preliminary clinical trials have explored tyrosine for a catecholamine-deficient subtype of depression. One small open trial (Gelenberg et al., 1982) reported early encouraging results for tyrosine versus imipramine. A separate case series found oral tyrosine at 3,200 mg/day reversed dopamine-dependent depression (DDD) based on MADRS scores. Evidence remains limited and mixed, with depletion studies showing inconsistent mood effects.

A. muciniphila abundance inversely correlates with depressive-like behavior in multiple animal models, and a systematic review and meta-analysis of 15 mouse studies confirmed it ameliorates depression-associated behaviors via gut-brain axis modulation, serotonergic pathways, and HPA axis regulation. Human association studies report inverse correlations between SCFA levels (a proxy for A. muciniphila activity) and depression severity. No human interventional RCT for depression as a primary endpoint has been completed.

Lower serum ALA levels are consistently observed in depressed individuals compared to healthy controls. Epidemiological data show an inverse relationship between ALA levels and depressive symptoms. ALA's conversion to EPA and DHA, both implicated in mood regulation, provides a plausible mechanistic link.

DHA from algal oil may reduce depressive symptoms by modulating serotonin and dopamine neurotransmitter systems. Consumption of larger amounts of DHA is associated with reduced risk of depression and mood disorders in epidemiological data. An RCT in APOE ε4 carriers found a significant effect of DHA+EPA on depression scores.

A 2024 mouse model study (Life Sciences) found that 4-week AGIQ administration alleviated stress-induced depressive behaviors via modulation of the microbiota-gut-brain axis, increasing 5-HT (serotonin) levels and maintaining gut barrier integrity. This is the first published evidence of AGIQ-specific antidepressant effects; all current evidence is preclinical.

Anchovies supply EPA and DHA, which have been studied in multiple RCTs and meta-analyses for depression. A 2019 PMC meta-analysis of 26 studies found a significant overall benefit of omega-3s on depressive symptoms (SMD=−0.28), with EPA-dominant formulations (≥60% EPA, ≤1 g/day) showing the strongest effects. Results are inconsistent across trials, with EPA appearing more active than DHA.

Timosaponin AIII and B-III from anemarrhena have shown antidepressant activity in established mouse behavioral models (open field test, tail suspension test, forced swimming test), matching or approaching the positive control fluoxetine. Sarsasapogenin also demonstrates antidepressant-like effects in animal models.

Ashwagandha (Withania somnifera) is an Ayurvedic adaptogen with preliminary but growing evidence for affective disorders including depression. Its withanolides modulate GABAergic and serotonergic pathways, suppress HPA axis hyperactivity, and reduce cortisol by 23–30% in RCTs. A 2018 systematic review of herbal psychiatry identified Ashwagandha as having preliminary evidence for affective disorders.

A. racemosus root extracts demonstrated antidepressant-like activity in rodent models (forced swim test, learned helplessness) and multiple PubMed-indexed reviews document the mechanism via HPA axis modulation, BDNF upregulation, and monoaminergic/GABAergic neurotransmission. A 2023 Heliyon review classifies A. racemosus as an adaptogen with well-characterized antidepressant properties across preclinical settings.

A small US RCT (n=28, 12 mg/day, 8 weeks) found a 57% reduction in self-rated depression scores and improvements in overall mood, although subjects were non-clinically depressed at baseline. A PMC narrative review notes that while animal studies support antidepressant-like effects through neuroinflammation reduction, human clinical evidence remains limited and of modest certainty.

Multiple PMC peer-reviewed reviews of Aster root pharmacology list antidepressant activity as a documented pharmacological property of Radix Asteris. Evidence is limited to preclinical (cell and animal) studies; no human antidepressant trials have been conducted with Aster root.

A randomized, double-blind, placebo-controlled, multi-centre pilot RCT (n=40, 90 days) found B. coagulans MTCC 5856 produced significant improvements (p=0.01) across multiple depression rating scales (HAM-D, MADRS, CES-D) in IBS patients with major depressive disorder. A separate 8-week RCT with W. coagulans BC99 also showed reductions in HAMD scores alongside gut microbiota shifts.

Bacopa monnieri (brahmi) has traditional Ayurvedic use for mood and cognitive enhancement and has been evaluated in clinical trials for anxiety and depression. Studies show bacosides reduce cortisol, improve serotonin turnover, and reduce depression scores in elderly populations. A systematic review identified brahmi (bacopa) among clinically studied botanicals for depression.

Bananas contain tryptophan, vitamin B6, magnesium, potassium, and iron—nutrients associated with serotonergic function and depressive symptom relief. A 2019 cross-sectional Chinese study investigated the association between banana consumption and depressive symptoms in a general adult population. A comprehensive review of 18 studies found most experimental trials reported positive antidepressant effects, though clinical trial results were mixed.

Berberine from barberry has demonstrated antidepressant-relevant activity in preclinical models, including modulation of monoamine neurotransmitters and neuroprotective effects. The gut-microbiome-brain axis mechanism links barberry's microbiome effects to mood regulation. Human clinical trial data for barberry/berberine in depression are limited.

Icariin has demonstrated antidepressant effects in multiple rodent models, including forced swim and chronic mild stress paradigms, by modulating monoamine neurotransmitter systems and reducing neuroinflammation. Animal studies show ICA increases BDNF, normalizes HPA axis activity, and reduces pro-inflammatory cytokines in brain tissue. No controlled human clinical trials for depression have been published.

Berberine has documented antidepressant-like activity across preclinical models and limited clinical data. It modulates monoamine neurotransmitter systems, reduces neuroinflammation, and promotes hippocampal neurogenesis. One clinical RCT in IBS patients showed berberine hydrochloride improved depression scale scores.

Bifidobacterium genus preparations, including strains closely related to B. bifidum, have demonstrated antidepressant effects via the gut-brain axis in both animal models and human RCTs. A meta-analysis of RCTs found Bifidobacterium-related preparations effectively improved depressive symptoms. B. bifidum specifically improved anxiety-like behavior induced by chronic intestinal inflammation in rodent models.

B. breve CCFM1025 was shown in a clinical RCT to significantly attenuate psychiatric and gastrointestinal symptoms in patients with major depressive disorder via regulation of tryptophan metabolism and the serotonergic system. B. breve A-1 improved anxiety and depression scale scores in schizophrenia patients in a proof-of-concept study. Preclinical data further support antidepressant-like effects through the gut-brain axis.

B. longum NCC3001 demonstrated significant improvement in depression scores in IBS patients in an RCT, associated with decreased emotional reactivity to fearful stimuli. Post-hoc analysis from a 6-week RCT in healthy adults found that reduced perceived stress correlated with reductions in depression scores. The gut-brain axis is the proposed mechanistic pathway.

A 2022 preclinical study in the Journal of Ethnopharmacology found that Platycladus orientalis seed extract acts as a potential triple reuptake MAO inhibitor, restoring monoamine neurotransmitters (serotonin, norepinephrine, dopamine) in zebrafish and rat depression models. This provides a pharmacological rationale for TCM's historical use of the seed for mood modulation. No human clinical trials have been published.

Black cohosh has been evaluated for perimenopausal depression and anxiety-related mood symptoms, with effects attributed to serotonergic and dopaminergic activity. A 2023 meta-analysis found improvements in overall menopausal symptoms but not specifically in depressive symptoms. Evidence in non-menopausal depression is lacking.

Clinical and pharmacological studies show N. sativa and thymoquinone have antidepressant-relevant activity. Human pilot trials and RCT protocols report improvements in depression scores in haemodialysis and other patient populations. Mechanistic work shows modulation of serotonin, dopamine, and GABA pathways.

Piperine exhibited antidepressant-like effects in animal models, reducing immobility and raising serotonin precursor (5-HTP) levels. In silico analysis identified multiple black pepper bioactive compounds with antidepressant activity via interaction with target proteins. MAO-B inhibition provides a plausible antidepressant mechanism. All meaningful evidence remains preclinical.

A PMC-indexed animal study (2024) specifically investigated Picea mariana essential oil in a reserpine-induced mouse model of depression. PMEO significantly improved depressive behaviors and was associated with upregulation of serotonin receptors (5HT-1A, 5HT-2A) and reduction of brain nerve injury. This is preclinical evidence only.

B. falcatum extracts have shown antidepressant-like effects in multiple rodent models, including the forced swim test and tail suspension test, associated with modulation of the HPA axis and central adrenergic pathways. A meta-analysis of RCTs found Bupleurum-containing Chinese herbal formulas reduced depression severity, though evidence was rated low quality. Bupleurum has been used for centuries in TCM as a Jie Yu (depression-relieving) herb.

Tributyrin is currently under investigation in a registered pilot RCT as add-on to antidepressant medication in MDD patients, reflecting growing mechanistic and preclinical evidence for butyrate's antidepressant potential via the gut-brain axis. A ButyraGen (tributyrin-containing) clinical study reported a twofold greater likelihood of improvement in depression symptoms in participants without GI disease. Preclinical models of depression consistently show butyrate's antidepressant-like effects. Clinical evidence in humans specifically for depression remains preliminary.

Preclinical studies demonstrate that sodium butyrate reduces depression-like behaviors via the gut-brain axis, suppressing hippocampal neuroinflammation and neuronal ferroptosis. Human evidence is indirect, linking lower butyrate-producing bacteria to depression diagnoses and supporting a clinical trial in schizophrenia/cognitive disorders.

Moderate caffeine intake has been associated in observational and meta-analytic evidence with a reduced risk of depression, via adenosine antagonism that modulates dopaminergic and serotonergic systems. A 2025 PMC comprehensive review concluded that low-to-moderate caffeine may reduce depression risk and improve general mental health. High intake may have the opposite effect.

Multiple RCT meta-analyses support a modest antidepressant effect of omega-3 supplementation, particularly EPA-dominant formulations. A meta-analysis of 26 double-blind RCTs (n=2,160) showed an overall beneficial effect (SMD=−0.28). Calamari oil is notably higher in DHA, and evidence suggests EPA is the more active component for depression; results are mixed for DHA-dominant formulations.

Multiple preclinical studies show BCP exerts antidepressant-like effects via CB2 receptor activation and modulation of catecholaminergic neurotransmitter systems. A 2025 rodent study found chronic BCP improved recognition memory and reduced cytokines in a treatment-resistant depression model. No human RCTs have been published.

A 2022 RCT found celery seed extract reduced depression scores (BDI) in hypertensive patients. Preclinical work and a scoping review indicate NBP and celery methanolic extract improve depression-related behavioral endpoints, comparable to fluoxetine in animal models.

Chamomile (Matricaria chamomilla) is a traditional European herb with clinical evidence for anxiety and depression. A long-term RCT (n=93) found chamomile extract at 1,500 mg/day significantly reduced GAD recurrence and showed antidepressant effects. A 2025 systematic scoping review of 209 depression trials listed chamomile among herbs warranting further research for depression.

A randomized controlled trial (Tayebi et al., 2021) tested Vitex agnus-castus in postmenopausal women and reported reduced depression scores, attributing effects to hormonal and neuromodulatory activity. VAC is also tested as part of PMS management where depressive mood is a primary endpoint. Evidence is preliminary; no large dedicated trials in primary depressive disorder exist.

Several clinical trials have investigated chromium picolinate specifically in atypical depression, a subtype characterized by mood reactivity, carbohydrate craving, and hypersomnia. A pilot RCT at Duke University (n=15) and a multicenter 8-week RCT (n=113) both found improvements in atypical depression symptoms, particularly in patients with high carbohydrate cravings. Proposed mechanisms include 5-HT2A receptor downregulation and enhanced insulin sensitivity.

Chromium picolinate has been studied specifically in atypical depression (characterized by carbohydrate craving, mood reactivity, and hypersomnia) with promising results in small controlled trials. A pilot RCT found that 70% of chromium-treated patients met responder criteria versus 0% on placebo. A larger multicenter replication found benefit specifically in the subgroup with high carbohydrate craving. The proposed mechanism involves 5-HT2A receptor downregulation and enhanced central insulin sensitivity.

Chrysin produces antidepressant-like effects in rodent models, primarily through GABAergic and serotonergic mechanisms, and also by activating BDNF and NGF. Both low and high doses show distinct anti-immobility effects in the forced swim test, with high-dose effects similar to fluoxetine. All evidence is preclinical.

A randomized double-blind placebo-controlled trial found citicoline effective as an adjuvant to citalopram in major depressive disorder. Additional exploratory clinical data support its use in post-stroke depression alongside cholinergic mechanisms. Evidence remains limited by small sample sizes and the absence of large confirmatory trials.

C. sinensis essential oil, rich in linalool and limonene, has been shown in human studies to improve mood and reduce depressive symptoms in patients undergoing medical procedures. Preclinical behavioral tests confirm antidepressant-like effects of C. sinensis extracts. The mechanism involves olfactory-serotonergic pathway modulation.

An 8-week randomized double-blind placebo-controlled trial in middle-aged women found that cacao flavanol supplementation significantly reduced indicators of negative mood including depression versus placebo. Cocoa's neuroactive compounds (theobromine, phenylethylamine, flavanols activating CREB/BDNF) provide plausible mechanisms. Evidence is preliminary and requires larger trials.

EPA and DHA in cod liver oil are associated with reduced depressive symptoms through anti-inflammatory and neurotransmitter-modulating mechanisms. Multiple observational studies and RCTs support omega-3 supplementation for depression, with EPA showing the strongest antidepressant signal. Evidence is particularly strong in elderly and high-inflammation populations.

CoQ10 (ubiquinone) has been studied as an adjunct for depression, particularly in patients with mitochondrial dysfunction and treatment-resistant depression. A 2021 PMC review identified CoQ10 among agents with evidence for improving depressive symptoms. It reduces oxidative stress, supports mitochondrial energy production, and modulates monoamine levels.

Creatine has emerging evidence as an adjunct for depression, particularly in treatment-resistant and female depression. A randomized controlled trial found creatine monohydrate augmentation of SSRI therapy significantly improved HAM-D scores. It addresses impaired brain bioenergetics (phosphocreatine/ATP system) documented in MDD.

Creatine monohydrate has RCT evidence for adjunctive antidepressant effects, particularly in women with SSRI-resistant depression. A double-blind RCT (n=52) found creatine 5 g/day added to escitalopram significantly improved HAM-D scores versus placebo. It restores impaired brain bioenergetics (phosphocreatine/ATP system) documented by neuroimaging in MDD.

Curcumin, the primary bioactive compound of turmeric, has been evaluated in multiple RCTs for depression. A 2025 meta-analysis of 15 RCTs (n=1,123) found a statistically significant reduction in depressive symptoms (SMD = −0.65). It modulates neuroinflammation, HPA axis, BDNF, and multiple neurotransmitter systems. A 2017 meta-analysis also concluded curcumin is safe and efficacious in depressed patients.

Preclinical studies show antidepressant-relevant neurochemical effects for damiana, including MAO-B inhibition and inhibition of dopamine and noradrenaline reuptake. The British Herbal Pharmacopoeia lists depression as an indication. Animal studies confirm mood-enhancing behavioral effects. No human trials exist.

DHA is a long-chain omega-3 fatty acid involved in neuronal membrane structure and neurotransmitter function. It contributes to antidepressant effects as part of omega-3 preparations, though EPA-predominant formulations generally show stronger effects. DHA supplementation has been shown to elevate red-cell membrane levels correlating with attenuation of depressive symptoms in clinical studies.

Multiple RCTs and a 2020 meta-analysis show DHEA supplementation significantly improves depressive symptoms compared to placebo. The effect size is modest (SMD −0.28) but statistically significant across 12 studies and 742 individuals. DHEA acts as a neurosteroid modulating GABA-A, NMDA, and sigma-1 receptors, and partially converts to estrogen and testosterone, which have independent mood effects.

Early clinical data (1950s–1970s) used deanol (DMAE) as a cerebral stimulant for mild depression and neurasthenia. A 1977 open clinical study of 14 senile dementia patients receiving DMAE 1,800 mg/day for four weeks found that 10 showed reduced depression, irritability, and anxiety alongside improved motivation. A double-blind RCT (Dimpfel et al., 2003) using a DMAE-containing combination showed significantly improved mood scores versus placebo on POMS and Bf-S questionnaires. Evidence is limited to older studies and multi-ingredient formulations.

Multiple clinical trials and meta-analyses support omega-3 PUFAs, including DHA, in reducing depressive symptoms, though EPA appears more efficacious as a standalone agent. A double-blind dose-finding pilot RCT found significant HAM-D reductions with 1–2 g/day DHA. A meta-analysis of 26 RCTs (n=2160) demonstrated an overall beneficial effect of omega-3 PUFAs on depression (SMD=−0.28, P=0.004). DHA contributes through modulation of serotonin, dopamine, and the HPA axis.

Cuscuta chinensis has been evaluated in randomized controlled trials for depression. A 2025 double-blind RCT found that C. chinensis extract as an adjunct to fluoxetine reduced BDI scores in mild-to-moderate depression. A prior triple-blind RCT (2015) using Cuscuta planiflora also showed benefits in major depression. These represent the strongest level of clinical evidence for any condition in the dodder literature.

Lower erythrocyte DPA levels have been observed in patients with schizophrenia, and DPA is gaining recognition as a bioactive molecule implicated in neuroinflammation and mental health. Preclinical studies show DPA can be incorporated into neuronal membranes and may influence neurotransmitter function. However, no clinical trials have specifically isolated DPA as an intervention for depression.

Multiple preclinical studies in rodent CUMS (chronic unpredictable mild stress) models demonstrate EGCG alleviates depression-like behaviors through inhibition of NLRP3 inflammasome activation, NF-κB/caspase-1 pyroptosis, and mTOR autophagy dysregulation. Epidemiological data link regular tea consumption to reduced depression risk. One small human RCT reported reductions in Hamilton Depression Scale scores in psychiatric patients, though not statistically differentiated from placebo.

EPA is the omega-3 fatty acid most consistently linked to antidepressant effects in human trials. Meta-analyses show supplements with ≥60% EPA significantly reduce depression severity scores, with effect sizes of approximately 0.53. EPA appears effective as adjunct therapy in major depressive disorder (MDD), including treatment-resistant cases.

Eleuthero has documented neuroprotective and monoamine-modulating effects relevant to depression, including elevation of noradrenaline, dopamine, and serotonin in preclinical models. BDNF upregulation has been observed. Traditional use for mood and nervous disorders is also recorded. Direct human RCT evidence for clinical depression is limited.

EPA, a long-chain omega-3 fatty acid, has the strongest evidence among omega-3s for depression. A meta-analysis of 26 RCTs (n=2,160) found overall beneficial effects on depression (SMD = −0.28); EPA-predominant formulations (≥60% EPA, ≤1 g/day) showed the most robust effects (SMD = −0.50 to −1.03). It is recognized by clinical guidelines as a Grade A adjunct for MDD.

Fava beans contain L-DOPA, a direct precursor to dopamine, as well as folate, which supports methylation pathways relevant to neurotransmitter synthesis including serotonin and dopamine. Psychiatric literature documents the dopaminergic potency of fava beans and their potential mood-relevant effects, though controlled trials in depressive disorders are lacking.

Ferulic acid demonstrates significant antidepressant-like effects in multiple animal depression models (forced swim test, tail suspension test, chronic unpredictable mild stress) via modulation of antioxidant enzymes (SOD, CAT, GSH-Px) and suppression of neuroinflammation (NF-κB, NLRP3, IL-1β, IL-6, TNF-α). Evidence is exclusively preclinical; dedicated human RCTs have not been published.

Fisetin exerts antidepressant-like effects in rodent forced swim and tail suspension tests via monoaminergic and TrkB mechanisms. It increases serotonin and noradrenaline in the frontal cortex and hippocampus and inhibits MAO-A activity. Evidence is entirely preclinical.

Omega-3 fatty acids from fish oil are among the most studied nutritional interventions for depression. Multiple meta-analyses of RCTs support a clinically meaningful antidepressant effect, particularly for EPA-dominant formulations (≥60% EPA) at doses ≥1 g/day. Epidemiological data consistently show an inverse relationship between fish consumption and depression prevalence across countries. Evidence is strongest for MDD treatment rather than prevention.

Observational and mechanistic evidence links higher omega-3 ALA intake (from flaxseed) to reduced depression risk, and omega-3 consumption is associated with improved mood and cognitive performance in human studies. However, a trial of flaxseed oil in children with bipolar disorder found no effect on depression symptoms.

Folate deficiency is consistently associated with depression, and folic acid supplementation has been studied as both a monotherapy and adjunct. Multiple clinical trials and a WFSBP/CANMAT 2022 guideline review found evidence supporting folic acid as an adjunct for MDD. MTHFR gene variants that impair folate metabolism are associated with antidepressant non-response.

Folate, including folinic acid, is implicated in depression because it is required for neurotransmitter synthesis and one-carbon methylation. Patients with depression frequently exhibit functional folate deficiency, low folate is associated with poor antidepressant response, and elevated homocysteine (a marker of folate insufficiency) correlates with depression severity. Folinic acid is used clinically as an adjunct or alternative in patients with impaired folate metabolism.

Preclinical rodent studies show P. cocos water extract exerts antidepressant-like effects in unpredictable chronic mild stress (UCMS) and forced swimming test (FST) models, increasing sucrose preference and reducing immobility. Mechanisms involve elevation of dopamine and serotonin in the frontal cortex and downregulation of neuroinflammation. No human clinical trials exist for depression as a primary endpoint.

GABA deficiency is consistently found in patients with depression, evidenced by reduced occipital and prefrontal cortex GABA levels on MRS neuroimaging. Multiple antidepressants increase GABAergic neurotransmission as part of their mechanism. Oral GABA supplementation has shown modest anxiolytic and mood-supporting effects in limited clinical studies.

A pilot RCT in breast cancer patients found significantly less self-reported depression with Ganoderma spore powder after 4 weeks. A Cochrane-style systematic review protocol covering mood disorders including depression has been formally registered. Serotonergic pathway upregulation provides a plausible mechanism.

Geniposide and related iridoids from Gardenia jasminoides exhibit antidepressant-like effects in rodent models via HPA axis normalization and neuroprotective mechanisms. Kampo formulas containing gardenia showed antidepressant effects comparable to paroxetine in menopausal women. A 2023 meta-analysis found TCM formulas with Gardenia Fructus significantly reduced Hamilton Depression Scale scores versus no treatment.

Crocin and the iridoid fraction of Gardenia jasminoides have demonstrated antidepressant-like effects in multiple preclinical rodent models of depression (CUMS, forced-swim, tail-suspension tests) via PKA-CREB signaling pathway activation and modulation of the HPA axis. Geniposide has also shown antidepressant activity in chronic unpredictable mild stress models. No human RCTs have been completed.

GE and its active compounds, particularly gastrodin and fermented GE, have shown antidepressant-like effects in animal models by upregulating monoamine neurotransmitters (serotonin, dopamine) and BDNF. A 2023 ScienceDirect review specifically examined GE's sedative-hypnotic and antidepressant properties.

Geranium aromatherapy has been used in clinical settings to reduce depressive symptoms, particularly in postmenopausal women. A study found that aromatherapy massage with geranium reduced depression severity in this population. Evidence is primarily from small RCTs and is considered preliminary.

Ginkgo biloba extract (EGb761) has been evaluated as an adjunct for depression in multiple trials. A 2024 systematic review and meta-analysis (21 studies, n=2,074 patients) found significantly better Hamilton Depression Scale scores in ginkgo-treated patients at 4, 6, and 8 weeks versus controls. It is most studied as an adjunct in elderly and post-stroke depression.

Ginseng and its ginsenosides have been studied for depression-related outcomes in clinical trials and systematic reviews. Ginsenosides modulate HPA axis activity, neurotransmitter systems, and neuroinflammation. A 2021 meta-analysis found ginsenoside supplementation significantly improved depressive symptoms in clinical populations.

Ginsenosides are the primary bioactive constituents of ginseng with evidence for antidepressant activity in both preclinical and clinical studies. They modulate HPA axis, BDNF, serotonin and dopamine systems, and reduce neuroinflammation. Clinical meta-analyses support their role in reducing depressive symptoms.

Multiple clinical neuroimaging and post-mortem studies have found altered glutamate levels in plasma, cerebrospinal fluid, and brain tissue of patients with major depressive disorder. Glutamatergic dysfunction—particularly at NMDA receptors—is now recognized as central to the pathophysiology of depression. Clinical trials of ketamine (an NMDA antagonist) have confirmed rapid antidepressant efficacy, providing direct evidence of the glutamate–depression link in humans.

In animal models of depression, LBP improved depressive behavior by enhancing synaptic plasticity and reducing neuroinflammation. A registered 6-week double-blind RCT in patients with major depressive disorder (ClinicalTrials.gov NCT04124276) investigated LBP's clinical antidepressant potential. Rodent studies show LBP reduces anxiety- and depression-like behaviors.

Small human studies report reductions in depression symptoms with Gotu Kola supplementation. The mechanism involves upregulation of serotonin, dopamine, and norepinephrine, and reduction of neuroinflammation. Animal studies confirm antidepressant-like behavioral effects. Evidence is preliminary and largely from small or open-label studies.

GPC (choline alfoscerate) is approved in several European countries for the treatment of pseudodepression in the elderly, which corresponds to subthreshold depression (StD). A 2025 clinical review concluded it improves mood regulation and motivation by acting on cholinergic dysfunction, dopamine, and serotonin systems. Evidence in frank major depressive disorder remains limited.

S. scardica extracts act as triple monoamine reuptake inhibitors in vitro—inhibiting reuptake of serotonin, noradrenaline, and dopamine—a mechanism directly relevant to antidepressant pharmacology. Antidepressant and psychostimulating effects have been confirmed in rodent models. Clinical trials showing mood improvement provide indirect supporting evidence, though dedicated human antidepressant RCTs have not yet been published.

A pilot double-blind randomized crossover RCT (36 breast cancer patients) assessed guarana for post-radiation depression and fatigue. Animal models show chronic guarana seed extract exposure produces anxiolytic effects involving dopaminergic and serotonergic neurotransmission. Traditional Amazonian medicine lists guarana among remedies for low mood and depression.

Linalool, comprising ~95–99% of ho wood essential oil, has demonstrated antidepressant-like effects in animal models and is the subject of a 2022 PMC review of its therapeutic role in depression. Traditional aromatherapy sources describe ho wood as used to 'soothe depression' and combat negative emotions.

A randomized, double-blind, crossover pilot RCT demonstrated that a hops dry extract significantly reduced self-reported depression scores (DASS-21) over 4 weeks in young adults with at least mild symptoms. In vitro evidence suggests hops constituents interact with serotonin receptor subtypes. Evidence is preliminary and from a single small trial.

Three small Chinese RCTs tested Huperzine A as an adjunct to antidepressants in major depressive disorder (MDD). A 2016 systematic review and meta-analysis (pooled n=238) found no statistically significant improvement in depressive symptoms, but significant advantages in cognitive functioning were observed. Evidence quality is low due to open-label, non-blinded designs and short durations.

A 2022 Wiley/BioMed Research International study in rats showed that standardized hydroethanolic extract of bael leaves (EAM) significantly attenuated depression-like behavior in a chronic unpredictable mild stress (CUMS) paradigm, reducing immobility time in forced swim and tail suspension tests and normalizing serotonergic system and HPA axis parameters.

Inositol has been studied in multiple RCTs for depression, primarily through its role as a second-messenger precursor in serotonin and noradrenaline receptor signaling. Several double-blind trials have shown inositol reduces HAM-D scores in MDD and is effective for treatment-resistant depression. Evidence is mixed in meta-analyses but biologically well-grounded.

Preclinical evidence shows antidepressant-like effects of standardized gypenosides through inhibition of neuroinflammation and modulation of brain-derived neurotrophic factor (BDNF) signaling in the hippocampus. These findings come from animal models; no dedicated human RCT for depression has been published.

Kanna alkaloids, particularly mesembrine, function as serotonin reuptake inhibitors and have demonstrated antidepressant-like activity in preclinical models. Human evidence is limited but includes a 6-week clinical trial reporting significant reductions in depression-related scores at 50 mg daily. Traditional use by San and Khoikhoi peoples for mood elevation forms an ethnobotanical basis consistent with antidepressant effects.

Kava (Piper methysticum) has substantial high-quality clinical evidence for anxiety disorders, which frequently co-present with depression. A systematic review of herbal psychiatry identified high-quality evidence for kava in anxiety, and RCTs demonstrate anxiolytic effects with antidepressant secondary outcomes. Active kavalactones modulate GABA-A receptors, serotonin receptors, and MAO-B.

A 2025 double-blind RCT (n=57 MDD adults, 8 weeks) found krill oil (520 mg EPA+DHA/day) significantly reduced Hamilton Depression Rating Scale scores versus placebo (p<0.001). Animal studies in chronic stress models show krill oil preserves brain DHA and attenuates depression-like behavior. Evidence parallels broader omega-3 PUFA literature but is limited in volume of krill-specific human trials.

Acetyl-L-carnitine (ALC), the brain-permeable form, has demonstrated antidepressant effects in multiple RCTs. A 2014 review found four RCTs showing ALC superior to placebo in depressive disorders; one trial showed equivalence to fluoxetine. Blood ALC levels are significantly reduced in patients with major depressive disorder.

Multiple clinical trials have investigated NAC (the acetylated prodrug of L-cysteine) as an adjuvant in major depressive disorder and bipolar depression, with a 2015 systematic review finding favorable evidence. The proposed mechanisms include glutamate modulation, GSH replenishment, and reduction of neuroinflammation. Most evidence is as adjunct therapy rather than monotherapy.

L-methionine is the biosynthetic precursor to SAMe (S-adenosyl-L-methionine) via the one-carbon cycle. SAMe is the principal methyl donor for synthesis of serotonin, dopamine, and noradrenaline; reduced SAMe levels are found in depressed humans. Clinical trials with SAMe at 200–1,600 mg/day show efficacy comparable to tricyclic antidepressants and modest adjunctive benefit with SSRIs. Direct L-methionine trials are limited but animal studies support antidepressant-like effects.

L-phenylalanine has been investigated as an antidepressant based on its role as a precursor to dopamine, norepinephrine, and phenylethylamine (PEA). Open-label human trials in the 1970s–1980s reported mood improvement in a subset of depressed patients. Evidence quality is low; controlled trials have not confirmed efficacy, and clinical interest has since waned. Phenylalanine/tyrosine depletion studies confirm the importance of this biosynthetic pathway to mood regulation.

L-serine is the biosynthetic precursor to D-serine, an endogenous NMDA-receptor co-agonist implicated in the glutamatergic hypothesis of major depressive disorder (MDD). Dysregulation of serine metabolism has been documented in MDD patients. A 2025 six-week randomized, double-blind, placebo-controlled trial of adjunctive D-serine in 44 adults with moderate-to-severe MDD found significant improvement in depressive symptoms, particularly in the severe subgroup.

Multiple human clinical trials — including RCTs — show L-theanine reduces depressive symptoms, both as monotherapy adjunct and in combination with antidepressants. A 6-week double-blind RCT found 200 mg/day added to sertraline produced significantly better HDRS scores than sertraline plus placebo. An open-label trial in MDD patients showed significant HAMD-21 reductions after 8 weeks at 250 mg/day. Mechanistic data from animal models points to modulation of monoamine neurotransmitters (serotonin, dopamine, norepinephrine) in limbic-cortical-striatal circuits.

L-Tryptophan is the dietary precursor to serotonin and melatonin. As an adjunct to antidepressants, studies from the 1970s–1980s showed positive antidepressant effects, and more recent evidence confirms its role as an augmentation strategy. Tryptophan depletion reliably precipitates depression relapse in remitted patients on SSRIs, confirming mechanistic relevance.

L. acidophilus has been studied in clinical RCTs as part of multi-strain probiotic formulations targeting depression via the gut-brain axis. A 2024 RCT in IBS patients with subthreshold depression found that a drink containing L. acidophilus LA-5 significantly raised serotonin levels versus placebo. Meta-analyses of Lactobacillus-based interventions generally report reductions in depressive symptom scores, though L. acidophilus is rarely isolated as the sole active agent. Evidence for multi-strain formulas including L. acidophilus is stronger than for single-strain use.

L. paracasei CCFM1229 reduced depressive and anxiety behavior in a chronic stress mouse model by regulating xanthine oxidase activity in the brain and maintaining CNS myelin structural stability. Human RCT data for L. paracasei specifically targeting depression are limited, but the PS23 RCT in stressed office workers assessed depression as a secondary outcome.

Multiple RCTs and a meta-analysis document L. plantarum strains reducing depressive symptoms as measured by validated scales (BDI, DASS). Strain-specific effects are reported for PS128, P8, and JYLP-326.

A 423-person double-blind RCT (Slykerman et al. 2017) found L. rhamnosus HN001 significantly reduced postpartum depression scores in women. Mechanistic animal studies show LGG modulates BDNF levels in brain tissue and reduces xanthine oxidase activity linked to depressive phenotypes. The gut-brain axis, through neuroendocrine and immune pathways, underpins these effects.

Lavender oil extract (Silexan) has been evaluated in RCTs for anxiety and depression. A systematic review found lavender among the most-studied botanical medicines with benefits comparable to standard anxiolytics and antidepressants. A 4-arm RCT (n=523) found Silexan 80–160 mg/day significantly superior to placebo for generalized anxiety with comorbid depressive symptoms.

Lemon balm (Melissa officinalis) has traditional use in European herbal medicine for anxiety and low mood, and modern clinical evidence supports its use for mood symptoms. A 2025 systematic scoping review of 209 depression trials found lemon balm among products with limited but promising evidence. It modulates GABA, serotonin, and HPA axis pathways.

Lily bulb has documented antidepressant pharmacological activity in rodent models and is the principal herb in the classical formula Bai He Di Huang Tang for 'Lily Disease', which maps onto major depression. Clinical systematic reviews confirm adjunctive efficacy of lily-bulb-containing formulas in human depression trials. A 2024 PMC comprehensive review found Lilium lancifolium and Rehmannia constitute a validated antidepressant pair.

Preclinical studies show limonene exerts antidepressant-like effects through reduced neuroinflammation, modulation of monoamine systems (dopamine, serotonin), and suppression of HPA-axis hyperactivity. One small clinical observation found that hospitalized depressed patients exposed to citrus fragrance (limonene-dominant) showed reductions on the Hamilton Rating Scale for Depression along with normalized immune biomarkers and reduced urinary cortisol. Human evidence is very limited.

Small but replicated clinical trials demonstrate antidepressant effects of Lion's Mane in humans. An 8-week trial found a 29.4% improvement in depression scores; a 4-week RCT in menopausal women showed significant improvement versus placebo. Animal data show restoration of serotonin, norepinephrine, and dopamine in the hippocampus.

Lithium orotate has been studied as a potential option for depression, including treatment-resistant depression. A 1986 open study by Sartori in 42 alcoholic patients reported improvements in depressive symptoms alongside alcoholism treatment. Reviews identify lithium orotate as a re-emerging candidate for depression, though robust placebo-controlled RCT data specific to the orotate salt remain limited.

Preclinical research has identified antidepressant-like mechanisms in lobelia. Beta-amyrin palmitate isolated from lobelia inflata showed antidepressant activity in forced swim test studies (Life Sciences 1993; J Pharm Sci 1992). Lobeline also modulates dopamine and norepinephrine, neurotransmitters central to depression. All evidence to date is from animal models; no human clinical trials have been conducted.

Neferine from lotus seed embryos shows antidepressant-like effects in animal models through serotonin receptor interactions. TCM documents lotus seed as treating mental low spirits and agitation. Human evidence is absent; current support is entirely preclinical.

Luteolin demonstrates antidepressant-like effects across numerous preclinical models via multiple mechanisms including PMAT inhibition, HPA axis regulation, anti-neuroinflammation, and glycerophospholipid metabolism modulation. A 2024 systematic review identified 17 preclinical studies. Human clinical confirmation is very limited.

Multiple small RCTs show maca reduces depression scores in postmenopausal women, operating independently of sex hormone changes. Animal models also demonstrate antidepressant-like biochemical effects. Dedicated trials in clinical depression populations are lacking.

Magnesium deficiency is associated with increased risk of depression. Multiple clinical studies have found supplementation reduces depressive symptoms, and a 2017 randomized clinical trial (n=126) found magnesium chloride (248 mg/day) effective for mild-to-moderate depression, comparable to antidepressants. It modulates NMDA receptor activity and HPA axis function.

Animal studies show honokiol and magnolol produce antidepressant-like effects via normalization of brain serotonin, noradrenaline, and BDNF levels in stressed rodent models. Human clinical data is indirect: the Relora® RCT (n=56) showed a significant 20% reduction in depression mood-state scores versus placebo. No dedicated human depression trials with magnolia as the sole agent currently exist.

Mangosteen xanthones have demonstrated antidepressant-related effects in preclinical models by modulating monoamine disturbances. A proof-of-concept RCT protocol was published for bipolar depression. A 24-week RCT in 148 schizophrenia patients tested 1,000 mg/day of mangosteen pericarp extract but did not find significant benefit on overall symptoms. Evidence remains largely preclinical.

Melatonin addresses circadian rhythm dysregulation, a recognized feature of depression. Clinical trials show melatonin improves sleep disturbance in depression and shows mild antidepressant effects. A 2022 Dove Medical Press review confirmed melatonin among supplements significantly reducing depression scores. It has mixed evidence per a 2025 scoping review.

B12 deficiency is associated with depression and neuropsychiatric symptoms, with MeCbl mechanistically linked via neurotransmitter synthesis, methylation, and homocysteine metabolism. B12 deficiency has been linked to increased prevalence of depression in observational studies. MeCbl supports serotonin and dopamine synthesis relevant to mood regulation.

Morinda officinalis oligosaccharides (MOO) are the most clinically studied active fraction for depression. A systematic review and meta-analysis of seven clinical studies (n=1,384) found MOO capsules non-inferior to conventional antidepressants such as fluoxetine for mild-to-moderate depression. Preclinical work shows MOO acts via the BDNF/TrkB/CREB pathway and gut-microbiota-mediated serotonin (5-HTP) production.

Limited human evidence suggests motherwort may improve depressive symptoms alongside anxiety. The same hypertension pilot study (Shikov 2011) reported improvement in depression parameters using the Clinical Global Impression scale in the majority of participants. This is supported by traditional classification as an antidepressant nervine, historically used to lift melancholy.

Preclinical studies show Ptychopetalum olacoides ethanol extract (POEE) produces dose-dependent antidepressant-like effects in rodent behavioral models. The mechanism appears to involve catecholaminergic (beta-adrenergic and D1 dopamine receptor) pathways rather than serotonin. Traditional use for 'nervous weakness' and lassitude by Amazonian communities aligns with these findings.

N-Acetyl Cysteine (NAC) has been studied as an adjunct for depression, particularly in bipolar depression. It is a glutathione precursor that normalizes glutamate transmission and oxidative stress. Multiple RCTs and meta-analyses have found NAC supplementation reduces depressive symptoms as an adjunct to standard treatments.

Naringenin exerts antidepressant-like effects in rodent models by enhancing neurogenesis, restoring monoaminergic balance, inhibiting MAO-A, and reducing neuroinflammation. A 2024 ScienceDirect study demonstrated naringenin combined with liraglutide relieved depressive symptoms in mice through neurogenesis promotion and inflammation reduction. Evidence is entirely preclinical.

Antidepressant activity of C. rotundus is listed as a proven pharmacological property in the comprehensive PMC 2023 review, citing Lin et al. as a reference. TCM clinical use for depression and Qi stagnation (a TCM correlate of depressive states) is well documented. Preclinical evidence includes CNS-active effects in animal models.

Omega-3 fatty acids, particularly EPA-predominant preparations, have robust clinical evidence for depression. A meta-analysis of 26 RCTs (n=2,160) found significant overall antidepressant effects (SMD = −0.28). Clinical guidelines (CANMAT/WFSBP 2022) assign omega-3 a Grade A recommendation as an adjunct for MDD, with EPA ≥60% and doses of 1–2 g/day showing the best results.

Seed extracts of P. orientalis have been studied for antidepressant potential in animal models, demonstrating monoamine reuptake inhibition and MAO inhibitory properties. A 2022 study in Journal of Ethnopharmacology identified P. orientalis seed extract as a potential triple reuptake MAO inhibitor capable of rescuing depression phenotype in zebrafish and rodent CUMS models. Plant-derived extracellular vesicles also showed antidepressant effects in mouse models.

Passionflower (Passiflora incarnata) has been studied in RCTs for anxiety and depression, with evidence of comparable efficacy to standard anxiolytics (oxazepam) for anxiety disorder. A systematic review of herbal psychiatry found high-quality evidence for passionflower in anxiety, and it appears in lists of botanicals with antidepressant activity in clinical reviews.

Rosmarinic acid, identified as the primary antidepressive compound in Perilla frutescens, reduced immobility duration in the forced-swimming test (a validated preclinical depression model) in mice. Traditional TCM use of Perillae Herba for affective disorders including depression and anxiety is documented. Human clinical trial data are lacking.

Multiple preclinical studies document rapid-onset antidepressant-like effects of Radix Polygalae extract, mediated via glutamatergic synapse modulation, BDNF induction, MAO inhibition, and HPA axis regulation. The active compound DISS (3,6'-disinapoyl sucrose) significantly reduced CORT, ACTH, and CRH in chronically stressed animals. No robust human RCTs have been published for depression specifically.

Multiple human studies link low CSF pregnenolone levels to major depressive and bipolar depressive episodes. A 12-week randomized, double-blind, placebo-controlled trial (n=80) at UT Southwestern found pregnenolone (titrated to 500 mg/day) significantly reduced bipolar depressive symptoms versus placebo. MGH is actively investigating pregnenolone for menopausal depression.

Progesterone's metabolite allopregnanolone (ALLO) modulates GABA-A receptors and exerts antidepressant effects; low ALLO is linked to postpartum depression (PPD), PMDD, and perimenopausal depression. FDA-approved brexanolone, a synthetic ALLO, validates this mechanism. However, natural progesterone supplementation for depression has mixed trial results, with some progestins associated with negative mood effects.

In an open-label clinical trial (n=17), PQQ disodium salt at 20 mg/day for 8 weeks produced significant improvement in the depression subscale of the POMS-SF compared to baseline. This is the primary human evidence; no placebo-controlled trial has specifically targeted depressive symptoms.

A double-blind RCT (Tang et al., 2005; n=132 neurasthenia patients) found reishi polysaccharide extract significantly improved mood and wellbeing versus placebo. A small RCT in breast cancer patients found reishi reduced depression during endocrine therapy. MSKCC notes subjective improvements in depression in clinical studies. Preclinical BDNF, serotonin, and neuroinflammation mechanisms are well characterised. Evidence is limited by trial scale and use of neurasthenia rather than DSM-5 MDD criteria.

Rhodiola rosea has been studied in clinical trials specifically for mild-to-moderate depression. A 2007 RCT of extract SHR-5 found significant improvements in HAM-D scores versus placebo. The European Medicines Agency approved its traditional use for stress-related symptoms including fatigue and low mood, and it acts via monoaminergic (serotonin, dopamine, norepinephrine) and HPA-axis mechanisms.

Multiple RCTs and a meta-analysis of 32 RCTs confirm Rosa damascena reduces depressive symptoms in adults. A 2025 RCT in menopausal women (n=82, 500 mg oral extract) showed depression scores drop from 10.1 to 3.9 versus an increase in placebo (p<0.001). Rosa damascena oil also reduced co-occurring depression symptoms in a separate 8-week RCT in men with MDD.

A randomized, double-blind, placebo-controlled trial demonstrated that rosemary capsules used adjunctively with SSRIs significantly reduced Beck Depression Inventory scores in patients with major depressive disorder. Rosemary tea also altered BDNF—a key depression biomarker—in healthy volunteers. Proposed mechanisms involve the monoaminergic system and anti-inflammatory actions of rosmarinic acid.

Rosmarinic acid exhibits antidepressant-like effects in preclinical models via modulation of BDNF/TrkB/PI3K signaling, glucocorticoid receptor nuclear translocation, and hippocampal neurogenesis. A 2022 human RCT found rosemary (containing quantified RA) significantly reduced BDI depression scores as adjunctive therapy to SSRIs over 8 weeks. A 2021 meta-analysis confirmed RA-rich lemon balm extract improves depression scores across multiple clinical trials.

Animal studies demonstrate RJ reduces depression-like behavior via adrenal steroidogenesis and BDNF modulation. One published clinical trial in post-stroke patients showed non-significant improvement in depression scores with RJ. Human evidence remains largely indirect, with the primary mechanistic work in murine models.

Saffron (Crocus sativus) has been evaluated in multiple RCTs for mild-to-moderate depression. Both stigma and petal extracts have been found significantly more effective than placebo and comparable in efficacy to fluoxetine and imipramine. A 2018 systematic review confirmed high-quality evidence supporting saffron for major depressive disorder.

SAMe is a naturally occurring methyl donor involved in monoamine neurotransmitter synthesis. A 2024 systematic review and meta-analysis of 23 RCTs (n=2,234) found SAMe significantly superior to placebo (SMD = −0.58) in reducing depressive symptoms. It is recognized by NCCIH-funded research and clinical guidelines as a viable adjunct for depression.

Sceletium's multi-modal pharmacology—SERT inhibition, PDE4 inhibition, MAO-A inhibition, and VMAT-2 upregulation—positions it mechanistically as an antidepressant. Pre-clinical rodent models show antidepressant-like activity comparable to escitalopram. A small proof-of-concept RCT in healthy older adults found improvements in mood alongside cognitive gains. Human clinical trials specifically in diagnosed depression patients remain sparse.

Polysaccharides from S. ningpoensis (SNPS) have been shown to exert antidepressant properties in a reserpine-induced mouse model of depression. The mechanism involves restoration of monoamine neurotransmitter homeostasis and hippocampal neurogenesis via HTR2A/HTR2C-mediated AKT/GSK3β/β-catenin/BDNF signalling. This is preclinical evidence; human studies are absent.

Multiple observational studies link low selenium intake or status with increased depressive symptoms, and some clinical trials show improvement with supplementation. A 2022 systematic review and meta-analysis (20 studies) found mixed results: supplementation showed a positive effect in some RCTs but a neutral effect in others. An optimal serum range (~82–85 µg/L) was associated with reduced depressive symptomatology in a study of 978 young adults. The proposed mechanism involves selenium's role in antioxidant defense via glutathione peroxidase and redox homeostasis.

Epidemiological studies and some intervention trials link low dietary selenium intake to increased prevalence of depressive symptoms, and vice versa. A 2022 systematic review and meta-analysis in Scientific Reports found a beneficial effect of selenium on depressive symptoms in three studies, though one clinical RCT found no significant effect. The link is biologically plausible via selenium's role in thyroid hormone metabolism and neurochemistry, but evidence is inconsistent and largely based on general selenium rather than selenomethionine-specific data.

A. julibrissin is empirically used as an antidepressant in TCM clinical practice and is backed by substantial preclinical evidence. Animal model studies demonstrate antidepressant-like effects mediated through serotonergic and dopaminergic pathways. Several clinical attempts combining Albizia formulae with conventional antidepressants have been conducted in depressed patients.

Silymarin has been studied for antidepressant activity in preclinical models and documented in a 2023 Frontiers in Neuroscience systematic review as having potential across psychiatric disorders including depression, operating via antioxidant, anti-inflammatory, and pro-estrogenic pathways. Human RCT data specific to depression diagnosis is very limited.

Antidepressant activity of P. hydropiper leaf extracts has been demonstrated in rodent behavioral models using the forced swim test and open field test. The chloroform and ethanol extracts showed significant reduction in immobility comparable to standard imipramine. Traditional use for depression and insomnia is also documented.

There is emerging clinical evidence that soy isoflavones may reduce depressive symptoms, particularly in peri- and postmenopausal women, likely via estrogenic modulation of mood-related pathways. Evidence from clinical trials is mixed but partially supportive.

The rodent study testing S. indicus extract in depression models (forced swimming and tail suspension tests) produced mixed results: significant effect was seen in the forced swimming test at high dose only, without a consistent antidepressant signal across both models.

D-series resolvins increase serotonin levels in depression models and activate mTOR/ERK signaling pathways relevant to antidepressant mechanisms. A human clinical trial of SPM precursors found significant improvements in depression scores in chronic pain patients. Neuroinflammation—countered by SPMs—is increasingly recognized as a depression driver.

St. John's Wort (Hypericum perforatum) is one of the most extensively studied herbal medicines for depression. A systematic review of 35 RCTs (n=6,993) found it superior to placebo (RR 1.53) and comparable to standard antidepressants for mild-to-moderate depression. Active constituents hyperforin and hypericin inhibit reuptake of serotonin, dopamine, and norepinephrine.

Sulforaphane shows antidepressant-relevant effects by modulating glucocorticoid receptors, reducing neuroinflammation, and upregulating the BDNF/CREB/ERK signaling axis. Animal studies demonstrate reversal of depressive behavior. Human RCT data in schizophrenia show improved negative symptoms which overlap with depressive phenomenology.

Multiple animal studies confirm antidepressant activity of A. calamus rhizome extract via serotonergic and antioxidant mechanisms. An Ayurvedic journal clinical study referenced in the literature assessed Vacha in depressive illness. Preclinical evidence is strong; independent human RCT data are lacking.

Taurine concentrations are diminished in the plasma, cerebrospinal fluid, and brains of patients with depression. Animal models consistently demonstrate antidepressant effects. A 7T MRI spectroscopy clinical study examined hippocampal taurine in human MDD, and mechanistic links to serotonin, dopamine, and HPA axis regulation are well-characterised.

In a clinical trial dataset from MgT-treated cognitively impaired older adults, MgT showed a significant negative correlation between baseline depression scores (GDS) and improvement after treatment, suggesting antidepressant benefit in those with elevated baseline depression. Preclinical work supports brain-magnesium-mediated mood effects.

Petroleum ether extract of T. cordifolia reversed depression-like behavior in mice and reduced monoamine oxidase (MAO) activity in the brain, increasing brain monoamine levels. This preclinical antidepressant evidence is complemented by its classification as a Rasayana herb affecting mental state in Ayurveda.

TMG augments SAMe, which is required for synthesis of serotonin, dopamine, and norepinephrine. In a RCT of 64 adults with depression, those taking SAMe plus TMG for 12 months showed greater symptom improvement than SAMe alone. A separate preliminary RCT compared SAMe plus betaine to amitriptyline, finding comparable outcomes with better tolerability. TMG has not been tested as monotherapy for depression in adequately powered human trials.

Clinical RCT data show reductions in depression-related mood subscores in moderately stressed individuals taking Tongkat Ali. The Talbott et al. (2013) POMS assessment captured depression as a subscale with favorable trends alongside improved cortisol/testosterone balance. Animal studies demonstrate antidepressant-like effects mediated via brain monoamine and HPA axis modulation. Direct RCTs specifically targeting clinical depression are absent; evidence is derived from mood-state studies in stressed, non-clinical populations.

Multiple RCTs and several meta-analyses support curcumin as an adjunctive treatment for major depressive disorder (MDD), with significant reductions in depressive symptom scores. A 2025 meta-analysis of 15 RCTs (1,123 participants) found a significant effect on depressive symptoms (SMD: −0.65, p=0.01). Curcumin also has documented traditional use in Ayurvedic medicine for mood disorders.

Animal studies show vanillin, administered via the olfactory pathway, alleviates depression-like behaviors and elevates brain serotonin and dopamine levels. A 2014 Psychiatry Research-published rat study demonstrated these monoamine neurotransmitter changes. No human clinical trials exist for vanilla as an antidepressant.

Randomized controlled trials have examined thiamine as adjuvant therapy in major depressive disorder, with some evidence of accelerated symptom reduction. A 12-week double-blind RCT in MDD patients receiving SSRIs found adjuvant thiamine significantly improved depressive symptoms at six weeks. Cross-sectional data show higher rates of suboptimal thiamine status among depressed individuals.

Vitamin B12 deficiency is associated with depressive symptoms, as B12 is essential for SAMe synthesis and myelin maintenance. Observational studies and clinical evidence support B12 repletion in deficient depressed patients, and supplementation has been associated with improved antidepressant response. It is listed among supplements studied for depression in multiple authoritative reviews.

Observational and cross-sectional research has found that patients with depression have significantly lower circulating nicotinamide (vitamin B3) levels than healthy controls, with moderate-to-large effect sizes. A 2023 Nutrients meta-analysis linked higher B-vitamin intake including niacin to lower depression prevalence. Mechanistically, niacin participates in tryptophan-serotonin metabolism; deficiency can reduce serotonin availability.

Vitamin B6 is a cofactor required for synthesis of serotonin, dopamine, and GABA, all implicated in depression. Epidemiological studies consistently associate higher B6 intake and plasma PLP with lower depression risk, and a systematic review supports benefit particularly in premenopausal women, though robust RCT evidence remains limited.

Folate (Vitamin B9) deficiency is closely linked to depression through its role in monoamine neurotransmitter methylation and SAMe biosynthesis. Clinical trials support folate supplementation as an adjunct for depression, particularly in patients with MTHFR polymorphisms. It is included in CANMAT/WFSBP 2022 MDD adjunct guidelines.

L-methylfolate (5-MTHF) is the bioavailable, active form of folate that directly supports monoamine neurotransmitter synthesis. It is FDA-approved as a prescription medical food (Deplin) for depression. RCTs show it significantly augments SSRI response in treatment-resistant depression, particularly in patients with MTHFR polymorphisms.

Vitamin D deficiency is strongly associated with depression, and multiple systematic reviews find supplementation modestly improves depressive symptoms. A meta-analysis of adjunctive nutraceuticals (American Journal of Psychiatry) identified primarily positive results for vitamin D in replicated studies. It is included in CANMAT/WFSBP 2022 guidelines as a Grade A adjunct for MDD.

Vitamin D3 (cholecalciferol) is the more bioavailable form of vitamin D studied in depression clinical trials. Its deficiency is consistently linked to depressive disorders, and supplementation is recommended as a Grade A adjunct for MDD by CANMAT/WFSBP 2022 guidelines. It regulates serotonin synthesis, neuroinflammation, and HPA axis function.

Clinical RCT evidence shows Bacopa monnieri reduces depression scores. The Calabrese et al. trial found CESD-10 depression scores decreased in the Bacopa group vs. placebo over 12 weeks. A 2024 systematic review of 22 clinical trials confirmed improvements in anhedonia and emotional function.

Yohimbine has been investigated for depression primarily as an augmenter of antidepressant therapy rather than as a monotherapy. Early research suggests it does not reliably improve depression symptoms when used alone. Some clinical trial evidence indicates it may reduce self-reported depressive symptoms when given as an adjunct to exposure-based psychotherapy, though findings are not consistent. It is also studied for reversing SSRI-induced sexual dysfunction.

Zinc is an essential trace element with consistent evidence linking deficiency to depression. Lower serum zinc is repeatedly found in depressed patients versus controls. Clinical trials show zinc supplementation reduces depressive symptoms as both monotherapy and adjunct to antidepressants, and dietary zinc intake is inversely associated with depression risk (RR 0.66).

Depression and mood disturbances were listed among the symptoms attributed to 'hypoadrenal syndrome' in the 1940s and are part of the traditional indication set for adrenal cortex extract. The HPA axis and cortisol dysregulation have established mechanistic links to depression in the scientific literature, but no clinical trial has specifically studied adrenal cortex supplement efficacy for depression.

TCM has long incorporated Baikal skullcap in prescriptions for depression. A 2024 systematic review and meta-analysis of 13 preclinical studies confirmed significant antidepressant effects in animal models, with mechanisms including antioxidant activity, modulation of neurotrophic factors, and anti-inflammatory action. No standalone human RCTs for depression are currently published.

California poppy is included in combination herbal formulas for depression in Western herbal medicine tradition. Bartram's Encyclopedia of Herbal Medicine lists depression as an indication. In vitro data show that protopine, an alkaloid in the plant, inhibits serotonin and noradrenaline transporters and exhibits antidepressant-like effects in mouse models. No human clinical trials specifically targeting depression exist.

Cardamom has traditional use in Ayurvedic medicine for supporting mood and alleviating depressive symptoms. Its aromatic volatile compounds (linalool, cineole) are used in aromatherapy for mood elevation. An animal study explored cardamom's effects on neuroinflammation and mood-related endpoints. Human clinical trial evidence for depression is absent.

Cowage seed contains L-DOPA, a precursor to dopamine, and animal studies show it raises dopamine, serotonin, and norepinephrine while lowering cortisol — all implicated in depression. A 2024 systematic review compiled preclinical evidence across multiple animal models. No controlled human clinical trials for depression specifically have been completed.

Depression is listed among the traditional indications for C. speciosa in TCM texts, cited in peer-reviewed pharmacological reviews. No mechanistic or clinical studies specifically addressing depression have been identified for this plant.

GLA is traditionally used and commercially marketed for depression, including postpartum depression, based on its role in eicosanoid regulation and membrane phospholipid composition important for neurotransmission. However, direct clinical evidence from well-controlled trials is limited, and it is primarily listed as a condition for which GLA is 'used' without strong RCT support.

A. vulgaris is documented in Ayurvedic, Asian, and European traditional medicine for depression, with MAO-inhibiting phenolics and GABA-A modulating constituents providing mechanistic plausibility. A non-peer-reviewed source cites a clinical observation of mugwort reducing depressive symptoms, but no controlled human trial data exist.

Depression and stress are among the documented traditional uses of Citrus sinensis across Chinese, Ayurvedic, and European herbal medicine. Orange essential oil's uplifting aroma has been used for mood elevation, and its warming digestive qualities are considered antidepressant in traditional practice. Clinical RCT evidence for orange specifically in depression is limited.

Paeonia lactiflora root has been used in TCM prescriptions for depression-like disorders for centuries. Preclinical studies show antidepressant-like effects via HPA axis modulation, neurotrophin upregulation, and monoaminergic pathways, but human clinical trial evidence remains insufficient.

Polygala root has long traditional use in TCM for depression and melancholia. Multiple preclinical studies demonstrate antidepressant-like effects via glutamatergic, monoaminergic, and BDNF-mediated mechanisms. A 2014 PubMed-indexed study showed rapid-onset antidepressant effects in mice, but human clinical trials for depression specifically are absent.

Pharmacological reviews document antidepressant properties of purslane alkaloids and omega-3 fatty acids in preclinical models. P. oleracea extracts have shown antidepressant activity in animal behavioral tests. No human RCTs specifically targeting depression endpoints with purslane were identified; the evidence is preclinical and mechanistic.

A 2022 PMC survey and review study found that over 55% of Saudi respondents used safflower to treat depression and anxiety, with 37% reporting it very effective. Several in vitro and in vivo studies provide preliminary positive evidence for antidepressant effects. No high-quality human RCTs exist; evidence is traditional use with preliminary scientific support.

Skullcap has traditionally been used for 'low spirits' and emotional exhaustion in Western herbalism. Preclinical evidence is growing: baicalin alleviates depression-like behavior in chronic restraint stress mouse models via BDNF-associated mechanisms. Human evidence specific to depression is absent—the Brock et al. (2014) trial deliberately excluded anxious/depressed participants.

In homeopathic Materia Medica (Boericke), Star of Bethlehem is associated with 'depression of spirits' and complete prostration arising in the context of severe chronic gastric disease. The Bach flower remedy system also includes it for emotional states resembling grief-induced low mood. Neither tradition constitutes clinical evidence, and no controlled trials have assessed Star of Bethlehem for depression specifically.

In TCM, CX is associated with the Liver meridian and is used to balance emotions, relieve liver qi stagnation, and address mood disturbances. Its liver-gallbladder-pericardium meridian associations and emotional regulation properties are documented in classical texts and TCM clinical practice, though clinical trials for depression specifically are not established.

Valerian (Valeriana officinalis) has centuries of use in European herbal medicine for nervous conditions, anxiety, insomnia, and mild depression. German Commission E and ESCOP monographs support its use for restlessness and sleep disturbance associated with depression. Clinical evidence is primarily for anxiety and sleep, with depression as a comorbid condition.

MP has been used in Ayurvedic medicine for nervous system disorders including mood disturbances. Preclinical animal studies demonstrate antidepressant effects via dopaminergic, serotonergic, noradrenergic, and anti-inflammatory pathways. A 2024 systematic review (MDPI Neurol Int) confirmed broad mechanistic evidence in animal models involving dopamine, serotonin, norepinephrine, cortisol reduction, and neuroinflammation. No human clinical trials have been conducted specifically for depression.

Adrenal extract is listed in traditional integrative medicine as a remedy for depression, historically linked to the observed overlap between low adrenal hormone states and depressive symptoms such as fatigue, low mood, and cognitive slowing. RxList and LAM Clinic sources document its traditional oral and sublingual use for depression. No clinical trials have investigated whole adrenal glandular as a treatment for depression.

Wood betony appears in traditional Western herbal practice as a thymoleptic (mood-lifting) nervine for low mood and depression linked to nervous exhaustion. Herbalist J.J. Pursell suggests combining it with St. John's wort for depression. No clinical evidence exists.