Effect of adjunctive single dose parenteral Vitamin D supplementation in major depressive disorder with concurrent vitamin D deficiency: A double-blind randomized placebo-controlled trial

The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials

The impact of vitamin D supplementation on depressive symptoms remains uncertain. This study aimed to investigate the dose-dependent effects of vitamin D supplementation on depressive and anxiety symptoms in adults. We systematically searched PubMed, Scopus, and Web of Science up to December 2022 to identify randomized controlled trials evaluating the effects of vitamin D3 supplementation on depression and anxiety symptoms in adults. Using a random-effects model, we calculated the standardized mean difference (SMD) for each 1000 IU/day vitamin D3 supplementation. The GRADE tool assessed the certainty of evidence. Our analysis included 31 trials with 24189 participants. Each 1000 IU/day vitamin D3 supplementation slightly reduced depressive symptoms in individuals with and without depression (SMD: -0.32, 95% CI -0.43 to -0.22; GEADE = moderate). The effect was more pronounced in those with depressive symptoms (SMD: -0.57, 95% CI -0.69 to -0.44; n = 15). The greatest reduction occurred at 8000 IU/day (SMD: -2.04, 95% CI -3.77 to -0.31). Trials with follow-up ⩽8 weeks (SMD: -0.45, 95% CI -0.70 to -0.20; n = 8) and 8 to ⩽24 weeks (SMD: -0.47, 95% CI -0.70 to -0.24; n = 15) showed stronger effects compared to those lasting 24 to ⩽52 weeks (SMD: -0.13, 95% CI -0.28 to 0.02; n = 5) or longer than 52 weeks (SMD: 0.14, 95% CI -0.16 to 0.44; n = 3) (p group difference <0.001). Vitamin D3 supplementation had no significant effects on anxiety symptoms. In summary, this study suggests that vitamin D3 supplementation may effectively reduce depressive symptoms in short term. Further high-quality trials are warranted for a conclusive assessment of its impact on anxiety.

How Follow-Up Period in Prospective Cohort Studies Affects Relationship Between Baseline Serum 25(OH)D Concentration and Risk of Stroke and Major Cardiovascular Events

Background/Objectives: Prospective cohort studies are useful for studying how biomolecular status affects risk of adverse health outcomes. Less well known is that the longer the follow-up time, the lower the association (or "apparent effect") due to "regression dilution". Here, we evaluate how follow-up interval from baseline to "event" affects the relationship between baseline serum 25-hydroxyvitamin D [25(OH)D] concentration and the later incidence of stroke and major cardiovascular events (MACEs). Methods: Findings for the relative risk (RR) of stroke and MACEs with respect to serum 25(OH)D concentrations at baseline from prospective cohort studies were plotted against mean follow-up time. Fifteen studies from mainly European countries and the United States were used for stroke and nine studies for MACEs. Linear regression analyses were used to study data for follow-up periods of up to 10 years and for more than 10 years. Results: For stroke, the linear regression fit for 1-10 years is RR = 0.34 + (0.065 × follow-up [years]), r = 0.84, adjusted r2 = 0.67, p < 0.001. No significant variations in association were found for studies with follow-up periods of 10-20 years. For MACEs, the linear fit for 1-8.1 years is RR = 0.61 + (0.055 × follow-up [years]), r = 0.81, adjusted r2 = 0.59, p = 0.03. Discussion: The shorter the follow-up period, the greater the apparent effect of better vitamin D status in reducing risk of stroke and MACEs. In addition, the apparent effect of higher 25(OH)D concentration found for the shortest follow-up time is more than twice as great as the estimate based on average follow-up intervals for all studies. Mechanisms have been found to explain how higher serum 25(OH)D concentrations could reduce risk of stroke and MACEs. Randomized controlled trials have not shown that vitamin D supplementation significantly reduces risk of either stroke or MACEs, probably because risk of both outcomes increases rapidly below 15 ng/mL (38 nmol/L) and it is difficult in Western developed countries to enroll enough participants with concentrations that low. Nonetheless, vitamin D's role in reducing risk of stroke and MACEs could be considered causal on the basis of an evaluation of the evidence using Hill's criteria for causality in a biological system. Conclusions: Serum 25(OH)D concentrations above 20 ng/mL are associated with significantly reduced risk of stroke and MACEs prospectively and in an apparent causal manner. Raising serum 25(OH)D concentrations to >20 ng/mL should, therefore, be recommended for everyone likely to be at risk for stroke or MACEs and indeed in the general population.

Combining Complementary and Alternative Medicine (CAM) with Conventional Treatments for Major Depressive Disorder

For many of the complementary and alternative (CAM) medicine methods, it is biologically plausible to expect that they could provide additional benefits in the treatment of major depressive disorder (e.g., enhanced initial response, augmentation, and tolerability) when combined with conventional treatments. Although most likely not comprehensively, herein we critically review current explicit clinical data pertaining to the most extensively evaluated CAMs in this setting: physical activity/exercise, mind and body methods, acupuncture, light therapy, diet, probiotics, various nutrients, and herbal preparations. While the absolute amount of data is enormous, the number of reliable primary studies (randomized controlled trials) and, particularly, meaningful meta-analyses of such studies are very limited. Consequently, the certainty of evidence about benefit or no benefit is very low for each of the addressed CAMs.

Vitamin D as a Modulator of Neuroinflammation: Implications for Brain Health

Neuroinflammation represents a critical immune response within the brain, playing a pivotal role in defense against injury and infection. However, when this response becomes chronic, it can contribute to the development of various neurodegenerative and psychiatric disorders. This bibliographic review delves into the role of vitamin D in modulating neuroinflammation and its implications for brain health, particularly in the context of neurological and psychiatric disorders. While vitamin D is traditionally associated with calcium homeostasis and bone health, it also exerts immunomodulatory and neuroprotective effects within the central nervous system. Through comprehensive analysis of preclinical and clinical studies, we uncover how vitamin D, acting through its receptors in glial cells, may influence the production of proinflammatory cytokines and antioxidants, potentially mitigating the cascade of events leading to neuronal damage. Clinical research has identified vitamin D deficiency as a common thread in the increased risks of multiple sclerosis, Parkinson's disease, Alzheimer's, and depression, among others. Furthermore, preclinical models suggest vitamin D's regulatory capacity over inflammatory mediators, its protective role against neuronal apoptosis, and its contribution to neurogenesis and synaptic plasticity. These insights underscore the potential of vitamin D supplementation not only in slowing the progression of neurodegenerative diseases but also in improving the quality of life for patients suffering from psychiatric conditions. Future clinical studies are essential to validate these findings and further our understanding of vitamin D's capacity to prevent or alleviate symptoms, opening new avenues for therapeutic strategies against neuroinflammation-related pathologies. Neuroinflammation is a crucial immune response in the brain against injuries or infections, but its persistence can lead to diseases such as Alzheimer's, Parkinson's, multiple sclerosis, and depression. Cholecalciferol (Vitamin D3) emerges as a regulator of neuroinflammation, present in brain cells such as astrocytes and microglia, modulating immune function. Vitamin D's mechanisms of action include cytokine modulation and regulation of nuclear and mitochondrial genes. It adjusts inflammatory mediators and antioxidants, resulting in neuroprotective effects. Additionally, vitamin D impacts neurotransmitter synthesis and brain plasticity. This positions vitamin D as a potential adjunct in treating diseases like Alzheimer's and Parkinson's. Lastly, its role in intestinal microbiota and serotonin synthesis contributes to psychiatric disorders like schizophrenia and depression. Thus, vitamin D presents a novel therapeutic approach for neuroinflammatory, neurodegenerative, and neuropsychiatric diseases.

Vitamin D and depression in older adults: lessons learned from observational and clinical studies

Depression is a mental disorder triggered by the interaction of social, psychological and biological factors that have an important impact on an individual's life. Despite being a well-studied disease with several established forms of treatment, its prevalence is increasing, especially among older adults. New forms of treatment and prevention are encouraged, and some researchers have been discussing the effects of vitamin D (VitD) on depression; however, the exact mechanism by which VitD exerts its effects is not yet conclusive. In this study, we aimed to discuss the possible mechanisms underlying the association between VitD and depression in older adults. Therefore, we conducted a systematic search of databases for indexed articles published until 30 April 2021. The primary focus was on both observational studies documenting the association between VitD and depression/depressive symptoms, and clinical trials documenting the effects of VitD supplementation on depression/depressive symptoms, especially in older adults. Based on pre-clinical, clinical and observational studies, it is suggested that the maintenance of adequate VitD concentrations is an important issue, especially in older adults, which are a risk population for both VitD deficiency and depression. Nevertheless, it is necessary to carry out more studies using longitudinal approaches in low- and middle-income countries to develop a strong source of evidence to formulate guidelines and interventions.

The effect of vitamin D supplementation on depressive symptoms in adults: A systematic review and meta-analysis of randomized controlled trials

Neurosteroid and immunological actions of vitamin D may regulate depression-linked physiology. Meta-analyses investigating the effect of vitamin D on depression have been inconsistent. This meta-analysis investigated the efficacy of vitamin D in reducing depressive symptoms among adults in randomized placebo-controlled trials (RCT). General and clinical populations, and studies of ill individuals with systemic diseases were included. Light therapy, co-supplementation (except calcium) and bipolar disorder were exclusionary. Databases Medline, PsycINFO, CINAHL and The Cochrane Library were searched to identify relevant articles in English published before April 2022. Cochrane risk-of-bias tool (RoB 2) and GRADE were used to appraise studies. Forty-one RCTs (n = 53,235) were included. Analyses based on random-effects models were performed with the Comprehensive Meta-analysis Software. Results for main outcome (n = 53,235) revealed a positive effect of vitamin D on depressive symptoms (Hedges' g = -0.317, 95% CI [-0.405, -0.230], p < 0.001, I2 = 88.16%; GRADE: very low certainty). RoB assessment was concerning in most studies. Notwithstanding high heterogeneity, vitamin D supplementation ≥ 2,000 IU/day appears to reduce depressive symptoms. Future research should investigate possible benefits of augmenting standard treatments with vitamin D in clinical depression. PROSPERO registration number: CRD42020149760. Funding: Finnish Medical Foundation, grant 4120 and Juho Vainio Foundation, grant 202100353.

Vitamin D in Depression: A Potential Bioactive Agent to Reduce Suicide and Suicide Attempt Risk

Suicide is one of the leading causes of death worldwide. According to the World Health Organization (WHO), every year, more than 700 thousand people die from this cause. Therefore, suicide is a public health issue. The complex interaction between different factors causes suicide; however, depression is one of the most frequent factors in people who have attempted suicide. Several studies have reported that vitamin D deficiency may be a relevant risk factor for depression, and vitamin D supplementation has shown promising effects in the adjunctive treatment of this mood disorder. Among the beneficial mechanisms of vitamin D, it has been proposed that it may enhance serotonin synthesis and modulate proinflammatory cytokines since low serotonin levels and systemic inflammation have been associated with depression and suicide. The present narrative review shows the potential pathogenic role of vitamin D deficiency in depression and suicide and the potential benefits of vitamin D supplementation to reduce their risk.

Efficacy and acceptability of vitamin D supplements for depressed patients: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

This systematic review and meta-analysis synthesized the evidence from randomized controlled trials comparing vitamin D and placebo in reducing depressive symptoms and contributing to all-cause dropout rates.

METHODS

Inclusion criteria were randomized controlled trials comparing reduced depression between depressed patients receiving vitamin D and those receiving placebo. We searched PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials through January 2022.

RESULTS

Eighteen trials (1980 participants, median age 39 y) were included in the meta-analysis. Vitamin D supplements were significantly superior to placebo in reducing depression (standardized mean difference = -0.49; 95% confidence interval [CI], -0.75 to -0.23; I² = 81%). Depressed adults (standardized mean difference = -0.70; 95% CI, -1.09 to -0.31) responded to vitamin D significantly better than children and adolescents (standardized mean difference = 0.10; 95% CI -0.27 to 0.47). Vitamin D administered as bolus doses (oral intermittent high doses or intramuscular single high dose) appeared to be more effective than that taken daily by the oral route (P < 0.01). Patients with more severe depression tended to respond better than those with less severity (P = 0.053). We found no moderating effect of concurrent antidepressant use, presence of major depressive disorder diagnosis, physical comorbidity, sex, duration and doses of vitamin D supplement, serum 25-hydroxyvitamin D levels at baseline, and changes in serum 25-hydroxyvitamin D levels in the vitamin D group. Dropout rates were indifferent between the groups (17 trials; risk ratio = 0.84; 95% CI, 0.6-1.16; I² = 0).

CONCLUSIONS

Heterogeneous data suggested that vitamin D supplements are effective and safe for depressed patients.

Decreased Levels of Vitamin D in Bipolar Patients

Recently, vitamin D is considered a pleiotropic hormone, and as such, it has also become a topic of renewed interest in neuropsychiatry for its proposed role in the aetiology and pathophysiology of different psychiatric conditions, including mood disorders (MDs). This seems particularly crucial while considering the relatively high and often neglected prevalence of hypovitaminosis D in the general population and in specific groups, such as patients suffering from the most common type of MDs, which are major depression (MDD) and bipolar disorders (BDs). Therefore, in view of the controversial literature and findings on this topic and its potential therapeutic implications, the present study aimed at evaluating vitamin D levels in the plasma of a sample of inpatients fulfilling the DSM-5 criteria for mood episodes within BDs. The clinical picture was assessed by means of specific rating scales. The results showed that the vitamin D levels (mean ± SD, nM/L) of the bipolar patients of our sample were significantly lower (14.58 ± 11.27 nmol/L) than the normative values (>30 nmol/L). Eleven patients had sufficient values and only 4 had optimal, while 19 showed insufficient, 18 critical, and 17 severely critical levels. No differences emerged according to different socio-demographic or clinical features. In our opinion, the present findings strengthen previous research highlighting decreased vitamin D levels in bipolar patients and support the role of this pleiotropic hormone in BDs. Nevertheless, further studies should follow to corroborate the data of this preliminary study and to address the potential benefits of vitamin D supplementation in the treatment of MDs.

Efficacy of B-vitamins and vitamin D therapy in improving depressive and anxiety disorders: a systematic review of randomized controlled trials

OBJECTIVES

This systematic review aimed to evaluate the efficacy of B vitamins and vitamin D therapy in improving the standard treatment of depression and anxiety disorders. We also aimed to gather the evidence supporting the recommendations for supplementation in clinical practice.

METHODS

Performed between March 2020 and September 2021, the main inclusion criteria were randomized controlled trials (RCTs), with patients ≥ 18 years old, both sexes, fulfilling target diagnoses of major depressive disorder (MDD), generalized anxiety disorder (GAD), or mild to severe depressive and anxiety symptoms. In addition, the RCTs were included if the scales to assess the severity of the symptoms were standardized rating scales in psychiatric. Trials that reported diagnoses of schizophrenia, perinatal depression, bipolar depression, sleep disorders, eating disorders, cancer, and multiple sclerosis in association with any of the mentioned diagnoses were excluded.

RESULTS

We identified 20 RCTs that matched all eligibility criteria, totaling 2,256 subjects, diagnosed with MDD, GAD, and depressive or anxiety symptoms. Supplementation with folic acid or L-methylfolate, B1, B12 or methylcobalamin, and vitamin D (in different doses and study duration) significantly decreased depression score scales by increasing response to standard pharmacological treatment or as monotherapy, including partial or complete remission. As for anxiety symptoms, the availability of results is limited to adjuvant vitamin D therapy.

DISCUSSION

B vitamins and vitamin D associated with other compounds also showed significant results, so the improvement in symptoms cannot be attributed strictly to those. Our results suggest that intervention with B vitamins and/or vitamin D may be an effective and well-tolerated adjuvant strategy for improving the symptoms of depression and anxiety, according to the patient's clinical status and nutritional biomarkers.

Therapeutic and mechanistic intervention of vitamin D in neuropsychiatric disorders

Vitamin D deficiency is believed to affect between 35 and 55% of the world's population, making it a hidden pandemic. In addition to its role in bone and calcium homeostasis, vitamin D has also been linked in preclinical and clinical research to brain function. These outcomes have also been used for a variety of neuropsychiatric and neurodevelopmental problems. Nevertheless, these individuals are more prone to develop signs of cognitive decline. This review will emphasize the association between vitamin D and neuropsychiatric illnesses such as autism, schizophrenia, depression, and Attention Deficit Hyperactivity Disorder (ADHD). While numerous research show vitamin D's essential role in cognitive function in neuropsychiatric illnesses, it is too early to propose its effect on cognitive symptoms with certainty. It is necessary to conduct additional research into the associations between vitamin D deficiency and cognitive abnormalities, particularly those found in autism, schizophrenia, depression, and ADHD, to develop initiatives that address the pressing need for novel and effective preventative therapeutic strategies.

A randomized, double-blind, placebo-controlled, 12-week trial of vitamin D augmentation in major depressive disorder associated with vitamin D deficiency

BACKGROUND

Randomized controlled trials (RCTs) of vitamin D (VitD) supplementation for depression have yielded inconsistent results. We conducted the first RCT of VitD supplementation with multipoint serum 25(OH)D assessments in major depressive disorder (MDD) patients with concurrent severe VitD deficiency.

METHODS

We randomized antidepressant-free depressed adults with mean baseline 25(OH)D of 11.5 ng/ml to VitD (60,000 IU every 5 days; n = 31) or placebo (n = 28) for 12 weeks. All patients also received escitalopram (10-20 mg/day). Patients were rated at baseline and at the end of weeks 4, 8, and 12. Serum 25(OH)D was estimated at baseline, week 8, and week 12.

RESULTS

In an intent-to-treat analysis, mean Hamilton Depression Scale scores dropped from 25.7 to 5.7 and from 25.8 to 5.0 in VitD and placebo groups, respectively (primary outcome; P = 0.92). VitD and placebo groups did not differ on other objective and subjective ratings of depression, or on global ratings. Similar findings characterized completer analyses. No significant correlations were observed between 25(OH)D levels and depression ratings across the course of the study. Importantly, endpoint escitalopram doses were 4 mg/day higher in placebo than in VitD patients, and 4 mg/day higher in VitD deficient than in VitD sufficient patients.

LIMITATIONS

A ceiling effect with escitalopram may have prevented the discovery of benefits with VitD supplementation.

CONCLUSIONS

VitD supplementation does not improve antidepressant outcomes with flexibly dosed escitalopram. VitD deficient depressed patients may require higher antidepressant doses to experience benefits similar to those whose deficiency is corrected by VitD supplementation.

Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce

OBJECTIVES

The therapeutic use of nutrient-based 'nutraceuticals' and plant-based 'phytoceuticals' for the treatment of mental disorders is common; however, despite recent research progress, there have not been any updated global clinical guidelines since 2015. To address this, the World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Disorders (CANMAT) convened an international taskforce involving 31 leading academics and clinicians from 15 countries, between 2019 and 2021. These guidelines are aimed at providing a definitive evidence-informed approach to assist clinicians in making decisions around the use of such agents for major psychiatric disorders. We also provide detail on safety and tolerability, and clinical advice regarding prescription (e.g. indications, dosage), in addition to consideration for use in specialised populations.

METHODS

The methodology was based on the WFSBP guidelines development process. Evidence was assessed based on the WFSBP grading of evidence (and was modified to focus on Grade A level evidence - meta-analysis or two or more RCTs - due to the breadth of data available across all nutraceuticals and phytoceuticals across major psychiatric disorders). The taskforce assessed both the 'level of evidence' (LoE) (i.e. meta-analyses or RCTs) and the assessment of the direction of the evidence, to determine whether the intervention was 'Recommended' (+++), 'Provisionally Recommended' (++), 'Weakly Recommended' (+), 'Not Currently Recommended' (+/-), or 'Not Recommended' (-) for a particular condition. Due to the number of clinical trials now available in the field, we firstly examined the data from our two meta-reviews of meta-analyses (nutraceuticals conducted in 2019, and phytoceuticals in 2020). We then performed a search of additional relevant RCTs and reported on both these data as the primary drivers supporting our clinical recommendations. Lower levels of evidence, including isolated RCTs, open label studies, case studies, preclinical research, and interventions with only traditional or anecdotal use, were not assessed.

RESULTS

Amongst nutraceuticals with Grade A evidence, positive directionality and varying levels of support (recommended, provisionally recommended, or weakly recommended) was found for adjunctive omega-3 fatty acids (+++), vitamin D (+), adjunctive probiotics (++), adjunctive zinc (++), methylfolate (+), and adjunctive s-adenosyl methionine (SAMe) (+) in the treatment of unipolar depression. Monotherapy omega-3 (+/-), folic acid (-), vitamin C (-), tryptophan (+/-), creatine (+/-), inositol (-), magnesium (-), and n-acetyl cysteine (NAC) (+/-) and SAMe (+/-) were not supported for this use. In bipolar disorder, omega-3 had weak support for bipolar depression (+), while NAC was not currently recommended (+/-). NAC was weakly recommended (+) in the treatment of OCD-related disorders; however, no other nutraceutical had sufficient evidence in any anxiety-related disorder. Vitamin D (+), NAC (++), methylfolate (++) were recommended to varying degrees in the treatment of the negative symptoms in schizophrenia, while omega-3 fatty acids were not, although evidence suggests a role for prevention of transition to psychosis in high-risk youth, with potential pre-existing fatty acid deficiency. Micronutrients (+) and vitamin D (+) were weakly supported in the treatment of ADHD, while omega-3 (+/-) and omega-9 fatty acids (-), acetyl L carnitine (-), and zinc (+/-) were not supported. Phytoceuticals with supporting Grade A evidence and positive directionality included St John's wort (+++), saffron (++), curcumin (++), and lavender (+) in the treatment of unipolar depression, while rhodiola use was not supported for use in mood disorders. Ashwagandha (++), galphimia (+), and lavender (++) were modestly supported in the treatment of anxiety disorders, while kava (-) and chamomile (+/-) were not recommended for generalised anxiety disorder. Ginkgo was weakly supported in the adjunctive treatment of negative symptoms of schizophrenia (+), but not supported in the treatment of ADHD (+/-). With respect to safety and tolerability, all interventions were deemed to have varying acceptable levels of safety and tolerability for low-risk over-the-counter use in most circumstances. Quality and standardisation of phytoceuticals was also raised by the taskforce as a key limiting issue for firmer confidence in these agents. Finally, the taskforce noted that such use of nutraceuticals or phytoceuticals be primarily recommended (where supportive evidence exists) adjunctively within a standard medical/health professional care model, especially in cases of more severe mental illness. Some meta-analyses reviewed contained data from heterogenous studies involving poor methodology. Isolated RCTs and other data such as open label or case series were not included, and it is recognised that an absence of data does not imply lack of efficacy.

CONCLUSIONS

Based on the current data and clinician input, a range of nutraceuticals and phytoceuticals were given either a supportive recommendation or a provisional recommendation across a range of various psychiatric disorders. However several had only a weak endorsement for potential use; for a few it was not possible to reach a clear recommendation direction, largely due to mixed study findings; while some other agents showed no obvious therapeutic benefit and were clearly not recommended for use. It is the intention of these guidelines to inform psychiatric/medical, and health professional practice globally.

Molecular Basis Underlying the Therapeutic Potential of Vitamin D for the Treatment of Depression and Anxiety

Major depressive disorder and anxiety disorders are common and disabling conditions that affect millions of people worldwide. Despite being different disorders, symptoms of depression and anxiety frequently overlap in individuals, making them difficult to diagnose and treat adequately. Therefore, compounds capable of exerting beneficial effects against both disorders are of special interest. Noteworthily, vitamin D deficiency has been associated with an increased risk of developing depression and anxiety, and individuals with these psychiatric conditions have low serum levels of this vitamin. Indeed, in the last few years, vitamin D has gained attention for its many functions that go beyond its effects on calcium–phosphorus metabolism. Particularly, antioxidant, anti-inflammatory, pro-neurogenic, and neuromodulatory properties seem to contribute to its antidepressant and anxiolytic effects. Therefore, in this review, we highlight the main mechanisms that may underlie the potential antidepressant and anxiolytic effects of vitamin D. In addition, we discuss preclinical and clinical studies that support the therapeutic potential of this vitamin for the management of these disorders.

Vitamin D and the risk of treatment-resistant and atypical depression: A Mendelian randomization study

Observational evidence has implicated vitamin D levels as a risk factor in major depressive disorder (MDD). Confounding or reverse causation may be driving these observed associations, with studies using genetics indicating little evidence of an effect. However, genetic studies have relied on broad definitions of depression. The genetic architecture of different depression subtypes may vary since MDD is a highly heterogenous condition, implying potentially diverging requirements in therapeutic approaches. We explored the associations between vitamin D and two subtypes of MDD, for which evidence of a causal link could have the greatest clinical benefits: treatment-resistant depression (TRD) and atypical depression (AD). We used a dual approach, combining observational data with genetic evidence from polygenic risk scores (PRS) and two-sample Mendelian randomization (MR), in the UK Biobank. There was some evidence of a weak association between vitamin D and both incident TRD (Ncases = 830) and AD (Ncases = 2366) in observational analyses, which largely attenuated when adjusting for confounders. Genetic evidence from PRS and two-sample MR, did not support a causal link between vitamin D and either TRD (Ncases = 1891, OR = 1.01 [95%CI 0.78, 1.31]) or AD (Ncases = 2101, OR = 1.04 [95%CI 0.80, 1.36]). Our comprehensive investigations indicated some evidence of an association between vitamin D and TRD/AD observationally, but little evidence of association when using PRS and MR, mirroring findings of genetic studies of vitamin D on broad depression phenotypes. Results do not support further clinical trials of vitamin D in these MDD subtypes but do not rule out that small effects may exist that require larger samples to detect.

Adverse health outcomes in vitamin D supplementation trials for depression: A systematic review

BACKGROUND

Vitamin D deficiency is a universal risk factor for adverse health outcomes. Since depression is consistently associated with low vitamin D levels as well as several adverse health outcomes, vitamin D supplementation may be especially relevant for depressed persons. This review examines the potential benefits of vitamin D for (somatic) health outcomes in randomised controlled supplementation trials for depression.

METHOD

Systematic literature search to assess whether adverse health outcomes, such as frailty, falls, or cognitive functioning, were included in vitamin D supplementation trials for depression, and whether these outcomes were affected by supplementation. The revised Cochrane tool for assessing risk of bias in randomised trials was used.

RESULTS

Thirty-one trials were included. Adverse health outcomes were considered in five studies. Two studies reported some beneficial effect on an adverse health outcome.

CONCLUSIONS AND IMPLICATIONS

While depressed persons are at increased risk of vitamin D deficiency, supplementation trials hardly addressed the common negative health consequences of low vitamin D levels as secondary outcome measures. Well-designed trials of the effects of vitamin D supplementation in late-life depression should explore whether adverse health outcomes can be prevented or stabilised, and whether depression benefits from this improvement.

Vitamin D in the time of the coronavirus (COVID-19) pandemic - a clinical review from a public health and public mental health perspective

Individuals with serious mental disorders (SMD) may have a higher risk of vitamin D (VIT-D) deficiency. They also experience higher mortality because of coronavirus disease 2019 (COVID-19) infection. Therefore, we have conducted a comprehensive review to examine the significance of VIT-D for public health and public mental health during the ongoing COVID-19 pandemic. This review had three specific aims, from a global perspective to (a) create a profile of VIT-D and review the epidemiology of VIT-D deficiency, (b) explore VIT-D deficiency as risk factor for SMD and COVID-19 infections and (c) examine the effectiveness of VIT-D supplementation for both conditions. We found that, in terms of SMD, the evidence from laboratory and observational studies points towards some association between VIT-D deficiency and depression or schizophrenia. Mendelian randomisation studies, however, suggest no, or reverse, causality. The evidence from intervention studies is conflicting. Concerning COVID-19 infection, on proof of principle, VIT-D could provide a plausible defence against the infection itself and against an adverse clinical course. But data from observational studies and the first preliminary intervention studies remain conflicting, with stronger evidence that VIT-D may mitigate the clinical course of COVID-19 infection rather than the risk of infection in the first place. From a public health and public mental health point of view, based on the currently limited knowledge, for individuals with SMD, the benefits of VIT-D optimisation through supplementation seem to outweigh the risks. VIT-D supplementation, however, should not substitute for vaccination or medical care for COVID-19 infection.

Vitamin D, Depressive Symptoms, and Covid-19 Pandemic

Since the COVID-19 outbreak, studies across diverse countries have strongly pointed toward the emergence of a mental health crisis, with a dramatic increase in the prevalence of depressive psychopathology and suicidal tendencies. Vitamin D deficiency has been associated with an increased risk of mental health problems as well as individual responses to stress. Studies have discussed the relationship between low serum vitamin D concentrations and depressive symptoms, suggesting that maintaining adequate concentrations of serum vitamin D seems to have a protective effect against it. Vitamin D was found to contribute to improved serotonergic neurotransmission in the experimental model of depression by regulating serotonin metabolism. The signaling of 1,25-dihydroxyvitamin D3, the active form of vitamin D, through vitamin D receptor (VDR) induces the expression of the gene of tryptophan hydroxylase 2 (TPH2), influences the expression of serotonin reuptake transporter (SERT) as well as the levels of monoamine oxidase-A (MAO-A), the enzyme responsible for serotonin catabolism. Vitamin D also presents a relevant link with chronobiological interplay, which could influence the development of depressive symptoms when unbalance between light-dark cycles occurs. In this Perspective, we discussed the significant role of vitamin D in the elevation of stress-related depressive symptoms during the COVID-19 pandemic. It is suggested that vitamin D monitoring and, when deficiency is detected, supplementation could be considered as an important healthcare measure while lockdown and social isolation procedures last during the COVID-19 pandemic.