Clinical Research

This randomized clinical trial of vitamin D–deficient patients with generalized anxiety disorder, found that adding weekly vitamin D supplementation to standard treatment improved anxiety symptoms and produced favorable changes in mood-related and inflammatory biomarkers over 3 months. The vitamin D group saw increases in Serotonin, a neurotransmitter associated with mood, and decreases in Neopterin, a marker of inflammation and oxidative stress. According to the study authors, “This supports the hypothesis that vitamin D actions in generalized anxiety disorder may be partly mediated through its anti-inflammatory effects that reduce oxidative stress, a mechanism previously suggested to contribute to vitamin D antidepressant effects.”

This study that looked at data from 12,232 participants in the National Health and Nutrition Examination Survey (NHANES) found that serum vitamin D level had a significant negative correlation with anxiety. Individuals with the highest vitamin D levels had about 22% lower odds of anxiety compared with those with the lowest levels. This effect remained significant even after fully adjusting for a wide variety of confounding variables.

This literature review and meta-analysis found that both vitamin D insufficiency and deficiency were significantly associated with an increased risk of Parkinson’s disease when compared with controls. Meta-data analysis showed that those with a vitamin D level below 20 ng/ml had a 2.5-fold increased risk of developing Parkinson’s disease. The study also found that at least 15 minutes of sunlight exposure per week was significantly associated with a reduced risk of Parkinson’s disease.

This ecological analysis that used data from 204 countries found that lower ambient ultraviolet radiation (UVR) levels are associated with higher dementia incidence rates worldwide, suggesting a critical role for UVR in mitigating dementia risk. The analysis found a significant inverse correlation between UVR and dementia incidence, which persisted after adjusting for confounding factors. According to the author, “UVR, through both vitamin D-dependent and independent mechanisms, influences physiological processes essential for brain health, such as reducing neuroinflammation, improving sleep regulation, and enhancing neuroplasticity.”

This study of 12,388 dementia-free participants at baseline found that vitamin D supplementation was associated with significantly longer dementia-free survival and lower dementia incidence rate than no supplementation over 10 years. Vitamin D supplementation was associated with 40% lower dementia incidence. These results suggest that vitamin D may play a role in dementia prevention, especially for those who are at high-risk.

This study that looked at the mental health of operating room nurses, who had little sunlight exposure due to their long work hours, found that this population had poorer mental health than the general population. The study found that poor mental health was associated with less sunlight hours, worse sleep regularity, and increased chronic disease. As the duration of sunlight exposure increased, survey respondents’ mental health status improved.

This retrospective review of 153 older adults with hypertension and mild cognitive impairment found significant improvements in recognition memory and systolic blood pressure following vitamin D supplementation (≥5,000 IU/day for at least 6 months) compared with a control group that received no or minimal supplementation. In adjusted multivariable regression analyses, the supplemented group showed an additional 1.8 point improvement in recognition memory and a 10.7 mmHg reduction in systolic blood pressure.

In this study that randomly assigned participants to either 50,000 IU vitamin D every 2 weeks or placebo for 8 weeks, they saw that those in the supplement group had a significant increase in vitamin D level and decreased depression severity. The control did not see significant change in either outcome.

This study of middle-age and older men, a higher depression index score was significantly associated with lower levels of 25(OH)D (p = 0.004). A 10 nmol/L decrease in 25(OH)D was associated with an average increase (worsening) of 5.2% in the BDI-II score. The odds of depression increased by around 70% across either decreasing quartiles or sufficiency categories of 25(OH)D.

Vitamin D, which has antioxidant properties and activity in brain tissue, is important for mood disorders preventions or treatments. Low vitamin D levels are associated with increased symptoms of depression and anxiety. This report dives into some of the ways vitamin D and UV light impact mental health.

This study found that adjusted regression models demonstrated 19% to 25% increased risk of all-cause dementia, Alzheimer's Disease (AD), and vascular dementia (VD) outcomes for those with vitamin D deficiency and 10% to 15% increased risk of those with vitamin D insufficiency. Regular users of vitamin D and multivitamins had 17% and 14% lower risk of AD and VD incidence, respectively.

This paper that reviewed data from two population-based studies found that having low sun exposure increased MS risk directly as well as indirectly, by affecting vitamin D status. The protective effect of sun exposure thus seems to involve both vitamin D and non-vitamin D pathways.

This double-blind, randomized, placebo controlled clinical trial found that high-dose oral vitamin D supplementation (100,000 IU of vitamin D twice per month) reduced disease activity in clinically isolated syndrome and in early relapsing-remitting multiple sclerosis when intervention was started less within 90 days of the start of clinically isolated syndrome.

In this study which tested 25(OH)D levels in 1,092 women in Finland an average of 9 years before their MS diagnosis and compared their outcomes with those of similar women who did not develop MS, women with 25(OH)D levels of less than 12 ng/mL had a 43% higher MS risk than women with levels 20 ng/mL or higher. Among the women with two or more serum 25(OH)D samples taken before diagnosis, a 20 ng/mL increase in 25(OH)D was associated with a 41% reduced risk of MS, and 25(OH)D levels less than 12 ng/mL were associated with an MS risk that was twice as high as levels of 20 ng/mL or higher.