This review summarises aspects of vitamin D metabolism, the consequences of vitamin D deficiency, and the impact of vitamin D supplementation on musculoskeletal health in older age. With age, changes in vitamin D exposure, cutaneous vitamin D synthesis and behavioural factors (including physical activity, diet and sun exposure) are compounded by changes in calcium and vitamin D pathophysiology with altered calcium absorption, decreased 25-OH vitamin D [25(OH)D] hydroxylation, lower renal fractional calcium reabsorption and a rise in parathyroid hormone. Hypovitaminosis D is common and associated with a risk of osteomalacia, particularly in older adults, where rates of vitamin D deficiency range from 10-66%, depending on the threshold of circulating 25(OH)D used, population studied and season. The relationship between vitamin D status and osteoporosis is less clear. While circulating 25(OH)D has a linear relationship with bone mineral density (BMD) in some epidemiological studies, this is not consistent across all racial groups. The results of randomized controlled trials of vitamin D supplementation on BMD are also inconsistent, and some studies may be less relevant to the older population, as, for example, half of participants in the most robust meta-analysis were aged under 60 years. The impact on BMD of treating vitamin D deficiency (and osteomalacia) is also rarely considered in such intervention studies. When considering osteoporosis, fracture risk is our main concern, but vitamin D therapy has no consistent fracture-prevention effect, except in studies where calcium is coprescribed (particularly in frail populations living in care homes). As a J-shaped effect on falls and fracture risk is becoming evident with vitamin D interventions, we should target those at greatest risk who may benefit from vitamin D supplementation to decrease falls and fractures, although the optimum dose is still unclear.

ObjectiveTo investigate the associations between low and high concentrations of baseline serum 25-hydroxyvitamin D [25(OH)D] and all-cause mortality in very old (≥85 years) men and women over 6 years.Design, setting and subjectsProspective mortality data from 775 participants in the Newcastle 85+ Study were analysed for survival in relation to 25(OH)D (season-specific quartiles and predefined cut-off values) and sex using Cox proportional hazards models. The models were fitted to the entire and restricted (nonusers of vitamin D-containing supplements and medication) cohorts.ResultsFor the entire cohort, mortality was higher in both the lowest and highest 25(OH)D season-specific quartiles [SQ1: hazard ratio (HR) 1.31, 95% confidence interval (CI) 1.01–1.69, P = 0.04; SQ4: HR 1.44, 95% CI 1.12–1.85, P = 0.004] compared with the combined middle quartiles (SQ2 + SQ3), after adjustment for sociodemographic factors. The increased risk for the highest quartile remained significant after further adjustment for lifestyle variables (SQ4: HR 1.37, 95% CI 1.06–1.77, P = 0.02) and was seen only in women in sex-specific analyses. Similarly, in sensitivity analyses with predefined 25(OH)D cut-off values, the highest 25(OH)D concentration (≥75 nmol L−1) was associated with a 2.4-fold increased risk of mortality in women (restricted cohort) after adjusting for all covariates.ConclusionLow and high season-specific 25(OH)D quartiles were associated with increased risks of mortality over 6 years in the very old; this effect was particularly noticeable in women, including those who reported taking vitamin D-containing supplements/medication.

There is an alarming high prevalence of vitamin D deficiency (<30 nmol/L) in 85-year-olds living in North East England at all times of the year but particularly during winter and spring. Use of vitamin D containing preparations (both supplements and medications) appeared to be the strongest predictor of 25(OH)D concentrations in these very old adults.

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