Thompson, MJW and Jones, G and Aitken, DA, Constitutive melanin density is associated with higher 25-hydroxyvitamin D and potentially total body BMD in older Caucasian adults via increased sun tolerance and exposure, Osteoporosis International pp. 1-9. ISSN 0937-941X (2018) [Refereed Article]
Introduction: Higher cutaneous melanin reduces vitamin D3 production. This may impact lifetime vitamin D status and increase fracture risk. This study aimed to describe the relationship between spectrophotometrically determined constitutive melanin density, osteoporotic risk factors and potential intermediaries in a cohort of exclusively older Caucasian adults.
Methods: One thousand seventy-two community-dwelling adults aged 50-80 years had constitutive melanin density quantified using spectrophotometry. Sun exposure, skin phenotype, non-melanoma skin cancer (NMSC) prevalence and smoking status were assessed by questionnaire. Bone mineral density (BMD), falls risk, physical activity and 25-hydroxyvitamin D were measured using DXA, the short form Physiological Profile Assessment, pedometer and radioimmunoassay, respectively.
Results: Higher melanin density was independently associated with greater ability to tan (RR = 1.27, p < 0.001), less propensity to sunburn (RR = 0.92, p < 0.001), fewer lifetime sunburns (RR = 0.94, p = 0.01), current smoking (RR = 1.41, p < 0.001), female sex (RR = 1.24, p < 0.001) and less photodamage (RR = 0.98, p = 0.01). The associations between melanin density and sun exposure (RR = 1.05-1.11, p < 0.001-0.01), sun protection behaviours (RR = 0.89, p < 0.001) and NMSC prevalence (RR = 0.75, p = 0.001) were no longer significant after taking into account skin phenotype and sun exposure, respectively. 25-Hydroxyvitamin D was strongly associated with higher melanin density (β = 1.71-2.05, p = 0.001). The association between melanin density and total body BMD (β = 0.007, p = 0.04) became non-significant after adjustment for 25-hydroxyvitamin D. There was no association between melanin density and physical activity, falls risk or BMD at other sites.
Conclusions: Our data support a model of higher constitutive melanin density underpinning a less photosensitive skin phenotype, permitting greater sun exposure with fewer sequelae and yielding higher 25-hydroxyvitamin D and, potentially, total body BMD.
|Item Type:||Refereed Article|
|Keywords:||BMD, fracture risk, melanin density, skin pigmentation, vitamin D|
|Research Division:||Medical and Health Sciences|
|Research Group:||Clinical Sciences|
|Research Field:||Rheumatology and Arthritis|
|Objective Group:||Clinical Health (Organs, Diseases and Abnormal Conditions)|
|Objective Field:||Skeletal System and Disorders (incl. Arthritis)|
|Author:||Thompson, MJW (Dr Michael Thompson)|
|Author:||Jones, G (Professor Graeme Jones)|
|Author:||Aitken, DA (Dr Dawn Aitken)|
|Deposited By:||Menzies Institute for Medical Research|
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