Gugger A, et al. - In this ancillary study of a 1-year, double-blind, randomized clinical trial conducted in Zurich, Switzerland, authors assessed 200 community-dwelling adults of aged ≥ 70 years to examine the influence of monthly high-dose vitamin D supplementation on mental health in pre-frail older adults. Subjects were given 24,000 IU vitamin D3 (considered a standard of care), 60,000 IU vitamin D3, or 24,000 IU vitamin D3 plus 300 μg calcifediol per month. The investigators observed substantial improvements in mental health scores among candidates with the highest 25(OH)D quartile at 12 months (44.7-98.9 ng/mL) after adjusting for confounders, and this association was strongest among subjects who were vitamin D deficient at baseline. Overall, compared with the standard monthly dose of 24,000 IU, higher monthly doses of vitamin D3 did not provide any mental health benefit. However, higher 25(OH)D levels at 12-month follow-up was associated with a small but statistically significant improvement in mental health scores, regardless of vitamin D treatment dose.