Supplementation of Vitamin D and Mental Health in Adults with Respiratory System Diseases: A Systematic Review of Randomized Controlled Trials.

Vitamin D is indicated to be beneficial for the prevention and treatment of both respiratory health and mental health problems, while mental health issues are a common consequence of diseases of the respiratory system. The aim of the presented systematic review was to gather available evidence regarding the influence of the supplementation of vitamin D on mental health in adults with respiratory system diseases obtained within randomized controlled trials (RCTs). The systematic review was conducted on the basis of the PubMed and Web of Science databases in agreement with the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), while being registered within the database of the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42020155779). A total of 8514 studies published before September 2021 were screened and 5 RCTs were included, which were assessed using the revised Cochrane risk-of-bias tool for randomized trials. Screening, inclusion, reporting, and assessment were conducted by two researchers independently. The studies focused on the assessment of patients with chronic obstructive pulmonary disease, but also increased susceptibility to respiratory tract infections, pulmonary tuberculosis, and bronchial asthma. The studies were conducted for various periods of time-from 2 months to a year-while the dose of vitamin D applied was also diverse-from 4000 IU applied daily, to 100,000 IU applied weekly, or monthly. The psychological measures applied within the studies allowed the assessment, mainly, of quality of life, but also well-being, and depression. For the majority of studies, some concerns regarding risk of bias were defined, resulting from the randomization process and selection of reported results; however, for one study, the risk was even defined as high. Within the included studies, three studies confirmed a beneficial effect of vitamin D (including those with a high risk of bias), but two studies did not confirm it. Taking into account the evidence gathered, in spite of a positive influence of vitamin D on mental health in individuals with increased susceptibility to respiratory tract infections and bronchial asthma, the conducted systematic review is not a strong confirmation of the beneficial effect of the supplementation of vitamin D on mental health in adults with respiratory system diseases.

Association between Vitamin D Supplementation and Mental Health in Healthy Adults: A Systematic Review.

Vitamin D is considered to be a crucial factor that influences symptoms of depression, negative emotions, and quality of life, but to date, no systematic review has been conducted with regard to its effect on other domains of mental health. The aim of the study was to evaluate the influence of vitamin D supplementation on mental health in healthy adults. The systematic review was registered in the PROSPERO database (CRD42020155779) and performed according to the PRISMA guidelines. The literature search was conducted in PubMed and Web of Science databases and included intervention studies published until October 2019. The human studies were included if the supplementation regimen involved the administration of a specified dosage of vitamin D to an adult sample. A total of 7613 records were screened and assessed independently by two researchers, based on their title, abstract, and full text sequentially. Finally, 14 studies were included, and their risk of bias was assessed using the Newcastle-Ottawa Scale (NOS). The studies were included if they presented the results of various doses of vitamin D, compared the supplementation results with the placebo effect, compared the outcome with no supplementation, or observed effect of specific dose applied. The assessed mental health outcomes mainly included depressive symptoms, or depression, well-being, quality of life, mood, general mental component, and anxiety, but single studies also included other parameters such as distress, impression of improvement, and fear of falling and flourishing. The results of the majority of studies did not confirm a positive influence of vitamin D supplementation. None of the high-quality studies (assessed using NOS), which evaluated outcomes other than depression, supported the hypothesis that vitamin D supplementation effectively ameliorates mental health issues, while they present conflicting evidence for depression. Some studies indicated that supplementation should be combined with physical activity to provide effective results, and that supplementation is less effective than vitamin D supply from food sources. The included studies were conducted in diverse populations and followed various doses and intervals of administration, so the results may be incomparable, which should be considered as a limitation. The conducted systematic review did not provide strong evidence for a positive effect of vitamin D supplementation on mental health in healthy adults.