Does increased sunlight exposure work as a strategy to improve vitamin D status in the elderly: a cluster randomised controlled trial
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Sunlight exposure by improving vitamin D status could be a simple public health strategy in reducing falls among frail elder people. In a randomised controlled trial, adherence to sunlight exposure was low (median adherence, 26%) and no effect of increased UV exposure on falls risk was observed (incidence rate ratio (IRR) 1.06, P = 0.73).
This study aimed to determine whether increased sunlight exposure was effective to improve vitamin D status and reduce falls in the elderly.
In a cluster randomised controlled trial (NCT00322166 at ClinicalTrials.gov), 602 residents aged 70 or more (mean age, 86.4 years; 71% female) were recruited from 51 aged care facilities in Northern Sydney, Australia. Participants were randomised by facility to receive either increased sunlight exposure (additional 30–40 min/day in the early morning) with (UV+) or without (UV) calcium supplementation (600 mg/day) or neither (control) for a year. The co-primary endpoints were change in serum 25 hydroxy vitamin D (25OHD) and falls incidence after 12 months.
Adherence to sunlight exposure was low (median adherence, 26%; IQR, 7%–45%). Serum 25OHD levels were low at baseline (median, 32.9 nmol/L) and increased only slightly depending on the number of sunlight sessions attended over 12 months (P = 0.04). During the study, 327 falls occurred in 111 (54%) subjects in the control group, 326 falls in 111 (58%) subjects in the UV only group and 335 falls in 108 (52%) subjects in the UV+ group. By intention-to-treat analysis, there was no significant effect of increased UV exposure on falls risk (IRR, 1.06; 95% CI, 0.76–1.48; P = 0.73). However, in 66 participants who attended ≥130 sessions per year (adherence, ≥50% of 260 sessions–five per week), falls were significantly reduced (IRR, 0.52; 95% CI, 0.31–0.88; P = 0.01) compared with the control group.
Increased sunlight exposure did not reduce vitamin D deficiency or falls risk in frail older people. This public health strategy was not effective most likely due to poor adherence to the intervention.
KeywordsAged care facility Elderly Falls Sunlight exposure Vitamin D deficiency
The authors gratefully acknowledge the support we received from the staff members in the participating institutions.
This work was supported by a project grant from the Australian National Health and Medical Research Council.
Conflicts of interest
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