Vitamin D insufficiency in Aboriginal Australians

Abstract

Objective: To investigate the adequacy of vitamin D status in a South Australian Aboriginal population, and to examine the relationship between serum 25‐hydroxyvitamin D (25‐OHD) levels and biochemical variables of calcium and bone mineral homeostasis, as well as other factors which may influence vitamin D synthesis, storage and metabolism. Design, setting and participants: A single‐visit, observational study of 58 adults from two Aboriginal community‐controlled health services in Adelaide and Yalata, South Australia. Participants were recruited between May 2008 and December 2009. Main outcome measures: Serum levels of 25‐OHD, parathyroid hormone (PTH), fasting glucose and fasting C‐terminal telopeptides of type I collagen (β‐CTx). Results: Serum 25‐OHD levels showed clear seasonal variation, being higher in summer (P < 0.001). The overall mean level was 56.8 nmol/L (SD, 22.1), which is below the recommended target level of 60 nmol/L. Serum 25‐OHD levels correlated significantly with β‐CTx (P = 0.03), but not with age, body mass index (BMI), PTH levels or levels of fasting glucose. A significant association was found between BMI and PTH levels (P = 0.001). A significant inverse association between serum 25‐OHD levels and BMI, observed in other studies, was not found in our study. Conclusions: Vitamin D insufficiency is highly prevalent in this population of adult Aboriginal Australians, with low mean values found in all seasons other than summer.

Clinical audit of health promotion of vitamin D in one general practice

“…The overall mean 25-OHD level (74.0 nmol/l) found in this audit was similar to the 76.9 nmol/l mean level found in a group of Adelaide residents[4] and higher than the 56.8 nmol/l mean level found in a recent study of adult Aboriginal Australians[5]. Furthermore, the audit confirmed the known seasonal variation in 25-OHD [5] by finding a high proportion of 25-OHD tests taken in summer compared to other seasons and a comparatively low proportion of patients with low levels of 25-OHD in summer.…”

“…Furthermore, the audit confirmed the known seasonal variation in 25-OHD [5] by finding a high proportion of 25-OHD tests taken in summer compared to other seasons and a comparatively low proportion of patients with low levels of 25-OHD in summer. In our audit, we did not measure the amount of time patients spent outside.…”

Serum vitamin D levels, diabetes and cardio-metabolic risk factors in Aboriginal and Torres Strait Islander Australians

“…We have reported a high percentage (31%) of vitamin D deficiency in this cohort from Northern and Central Australia, regions closer to the equator than previous Australian studies. The median 25(OH)D level (55 nmol/L) is similar to the mean 25(OH)D previously reported in a small study of 58 Aboriginal participants from South Australia (latitude 35 degrees south), of 56.8 nmol/L [12]. Of note, AusDiab, a nation-wide Australian population-based study, reported that 31% of Australians had 25(OH)D levels <50 nmol/L, however only 0.9% of AusDiab participants identified as Aboriginal or Torres Strait Islander Australians [6].…”

“…A recent systematic review reported a prevalence of 30-53% in ethnic minorities with dark skin versus 14-26% in those of Europid background [11]. Limited data from South Australia show that Indigenous Australians have a low vitamin D status [12]. However, approximately 40% of Indigenous Australians live at latitudes closer to the equator - in the tropical and subtropical regions of Australia [13].…”

Evidence-based D-bate on health benefits of vitamin D revisited

“…The IOM’s concern about skin cancer precluded them from making recommendations about sun exposure even though they acknowledged that casual sun exposure played an important role in a person’s vitamin D status. Humans have and continue to obtain a significant amount of their vitamin D requirement from sun exposure 7 , 10 , 11 , 17 , 42 . Although excessive exposure to sunlight increases risk for nonmelanoma skin cancer which is easy to detect and easy to treat there is no evidence that sensible sun exposure, as our hunter gatherer forefathers likely experienced, increases risk.…”