Effect of Monthly High-Dose Vitamin D on Mental Health in Older Adults: Secondary Analysis of a RCT.

OBJECTIVES: To test the effect of monthly high-dose vitamin D supplementation on mental health in pre-frail older adults.

DESIGN: Ancillary study of a 1-year double-blind randomized clinical trial conducted in Zurich, Switzerland.

SETTING AND PARTICIPANTS: A total of 200 community-dwelling adults 70 years and older with a prior fall event in the last year. Participants were randomized to receive 24 000 IU vitamin D3 (considered standard of care), 60 000 IU vitamin D3 , or 24 000 IU vitamin D3 plus 300 μg calcifediol per month.

MEASURES: The primary end point was the Mental Component Summary (MCS) of the SF-36. Secondary end points were the SF-36 Mental Health (MH) subscale and the Geriatric Depression Scale (GDS-15).

RESULTS: Participants' mean age was 78 years (67% women), and 58% were vitamin D deficient (<20 ng/mL). Over time, primary and secondary end points did not differ significantly among the three treatment groups or in subgroups by vitamin D status at baseline. Given the lack of a true placebo group, we explored in a predefined observational analysis the change in mental health scales by achieved 25(OH)D levels at 12 months. After adjusting for confounders, participants achieving the highest 25(OH)D quartile (Q) at 12 months (44.7-98.9 ng/mL) had the greatest improvements in MCS (Q4 = 0.79 vs Q1 = -2.9; p = .03) and MH scales (Q4 = 2.54 vs Q1 = -3.07; p = .03); these associations were strongest among participants who were vitamin D deficient at baseline. No association was found for GDS (p = .89).

CONCLUSIONS: For mental health, our study suggests no benefit of higher monthly doses of vitamin D3 compared with the standard monthly dose of 24 000 IU. However, irrespective of vitamin D treatment dose, achieving higher 25(OH)D levels at 12-month follow-up was associated with a small, clinically uncertain but statistically significant improvement in mental health scores.