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Type: Thesis
Title: Community perspectives on vitamin D and bone health in three at-risk populations.
Author: Vanlint, Simon John
Issue Date: 2013
School/Discipline: School of Population Health
Abstract: Background: Disorders affecting bone health, including osteoporosis and fractures, cause significant morbidity and mortality in Australia. Specific sub-groups within the general population are at increased risk of poor bone health and fracture. Such groups include people with intellectual disability, Aboriginal Australians and people known to have osteopenia. These studies aim to document the extent of this increase in risk, examine the underlying reasons and evaluate possible treatment options. Methods: Three studies are described: a) A 5 year retrospective audit of 280 individuals with intellectual disability examined data including age, gender, mobility, dietary status, incident fractures, medications and 25-hydroxyvitamin D (25D) levels, as well as response to vitamin D supplementation. b) A cross-sectional study of 58 South Australian Aboriginal people investigating the adequacy of vitamin D status and the relationship between serum 25D levels and biochemical variables of calcium and bone mineral homeostasis. c) A prospective, randomised, placebo-controlled pilot study of the efficacy, acceptability and tolerability of docosahexanoic acid (DHA) supplementation in addition to calcium and vitamin D₃ in 40 individuals with osteopenia. Results: a) 57% of intellectually disabled individuals tested were vitamin D insufficient. Vitamin D insufficiency was strongly correlated with reduced mobility (p<0.001) and difficulty consuming solids (p<0.001). The correlation between 25D levels and fractures was not significant (p = 0.3). Oral supplementation using vitamin D₃ 100,000 IU every 4 months was effective in correcting vitamin D insufficiency. 68 fractures occurred over the audit period in 52 individuals, a rate of 1 fracture every 23.8 person years. Peripheral fractures accounted for 54% of all fractures, being particularly prevalent in the most mobile individuals. b) Serum 25D levels varied seasonally in South Australian Aboriginal people, being higher in summer (P < 0.001). The overall mean of 56.8 nmol/L (SD, 22.1) is below the recommended target level of 60 nmol/L. Serum 25D levels correlated significantly with c-terminal telopeptide (CTx) (P = 0.03), but not with age, body mass index, levels of fasting glucose or PTH. BMI and PTH levels were significantly correlated with each other (P = 0.001). c) CTx was suppressed after 12 months for all osteopenic participants (p=0.04) with no difference in effect size between DHA and control groups (p=0.53). Changes in CTx at 12 months were significantly correlated with changes in bone density at the lumbar spine (p=0.01) and total proximal femur (TPF) (p=0.03). Participants rated the supplements as tolerable and acceptable, with few adverse events. Conclusions: a) Fractures are common in people with intellectual disability. Vitamin D insufficiency may contribute to this increased risk, although this study did not conclusively establish this. Oral vitamin D₃ supplementation is effective in restoring normal vitamin D levels. b) Vitamin D insufficiency is highly prevalent in adult Aboriginal Australians, with low mean values found in all seasons other than summer. c) The combination of oral calcium, vitamin D₃ and DHA was safe, tolerable and acceptable when used for 12 months by osteopenic individuals. Both combinations (i.e. calcium, vitamin D₃ and DHA; and calcium, vitamin D₃ and placebo) had a positive effect on bone health, with no significant effect from the addition of DHA.
Advisor: Newbury, Jonathan William
Dissertation Note: Thesis (Ph.D.)--University of Adelaide, School of Population Health, 2013.
Keywords: vitamin D; bone health; calcium; intellectual disability; Aboriginal health
Provenance: Copyright material removed from digital thesis. See print copy in University of Adelaide Library for full text.
Appears in Collections:Research Theses

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