Vitamin D supplementation for the prevention of depression and poor physical function in older persons: the D-Vitaal study, a randomized clinical trial

Abstract

Background: Depressive symptoms and impaired physical functioning are prevalent among older adults. Supplementation with vitamin D might improve both conditions, particularly in persons with low vitamin D status.

Objective: The D-Vitaal study primarily aimed to investigate the effect of vitamin D supplementation on depressive symptoms, functional limitations, and physical performance in a high-risk older population with low vitamin D status. Secondary aims included examining the effect of vitamin D supplementation on anxiety symptoms, cognitive functioning, mobility, handgrip strength, and health-related quality of life.

Methods: This study was a randomized placebo-controlled trial with 155 participants aged 60-80 y who had clinically relevant depressive symptoms, ≥1 functional limitations, and serum 25-hydroxyvitamin D [25(OH)D] concentrations of 15-50/70 nmol/L (depending on season). Participants received 1200 IU/d vitamin D3 (n = 77) or placebo tablets (n = 78) for 12 mo. Serum 25(OH)D was measured at baseline and 6 mo; outcomes were assessed at baseline, 6 mo, and 12 mo. Linear mixed-models analyses were conducted to assess the effect of the intervention.

Results: The supplementation increased serum 25(OH)D concentrations in the intervention group to a mean ± SD of 85 ± 16 nmol/L compared with 43 ± 18 nmol/L in the placebo group after 6 mo (P < 0.001). No relevant differences between the treatment groups were observed regarding depressive symptoms, functional limitations, physical performance, or any of the secondary outcomes.

Conclusions: Supplementation with 1200 IU/d vitamin D for 12 mo had no effect on depressive symptoms and physical functioning in older persons with relatively low vitamin D status, clinically relevant depressive symptoms, and poor physical functioning. This trial is registered with the Netherlands Trial Register (www.trialregister.nl) under NTR3845.

Keywords: 25(OH)D; depressive symptoms; functional limitations; older adults; physical functioning; physical performance; prevention; randomized clinical trial; supplementation; vitamin D.

FIGURE 1

Recruitment, selection, randomization, and follow-up of participants in the D-Vitaal study. *n = 2 excluded from the intention-to-treat analyses due to insufficient data. **In the CES-D, BAI, SF-36 MCS, and EQ-5D analyses, an additional n = 2 were excluded completely, and the 12-mo measurements were excluded for another n = 2. ***In the CES-D, BAI, SF-36 MCS, and EQ-5D analyses, an additional n = 1 was excluded completely, and the 12-mo measurements were excluded for another n = 3 in all per-protocol analyses. BAI, Beck Anxiety Inventory; CES-D, Center of Epidemiological Studies–Depression scale; CIDI, Composite International Diagnostic Interview; EQ-5D, EuroQol-5 Dimensions; MDD, major depressive disorder; SF-36 MCS, Short Form–36 Health Survey Mental Component Summary; vitD, vitamin D; 25(OH)D, 25-hydroxyvitamin D.

FIGURE 2

Mean scores of the primary outcome variables over time for the intervention and placebo groups. The error bars represent SEMs. n per group: (A) intervention: n = 75, placebo: n = 75; (B) intervention: n = 75, placebo: n = 76; (C) intervention: n = 30, placebo: n = 26; (D) intervention: n = 44, placebo: n = 50. P for interaction for the stratified analyses of number of functional limitations: P = 0.020. BL, baseline; CES-D, Center of Epidemiological Studies–Depression scale.