Concerns about vitamin D and sun exposure behaviour among Australians

ISSUES ADDRESSED

Australians' concerns about vitamin D and influence on sun protection were last quantified a decade ago in Queensland amidst media attention on emerging evidence of non-skeletal benefits of vitamin D. Meanwhile these circumstances persist and impact is worth assessing.

METHODS

Measures of concern about vitamin D were included in three recent population-based cross-sectional surveys of Australians' sun-related behaviours during summer months (2010-2011, 2013-2014 and 2016-2017). We analysed characteristics, beliefs and behaviours associated with vitamin D concerns regarding regular sunscreen use among adults in 2016-2017 (N = 3614).

RESULTS

Concerns about vitamin D continued to persist among adults surveyed between 2010-2011 and 2016-2017. Vitamin D concerns regarding the sunscreen use were more common among women, older respondents and adults with skin that tans or is not susceptible to sunburn. Respondents concerned about vitamin D were more likely to exhibit pro-tanning beliefs, scepticism about sunscreen safety and have attempted a suntan. They were also less likely to use sun protection in everyday activities outdoors and less likely to use sunscreen on summer weekends.

CONCLUSIONS

Vitamin D concerns related to sunscreen use remained common among Australian adults. Skin cancer control advocates may be reassured that those with the greatest skin cancer risk (burn only) were less likely to hold these concerns, while the related infrequent sun protection and tanning among concerned adults are problematic. SO WHAT?: Continued education and research is needed to ensure that the general public understand the risks and benefits of sun exposure in Australia.

Randomised Controlled Trial Comparing Daily Versus Depot Vitamin D3 Therapy in 0-16-Year-Old Newly Settled Refugees in Western Australia Over a Period of 40 Weeks

Vitamin D deficiency is highly prevalent in newly settled refugees in Western Australia (WA). If adherence to daily vitamin D therapy is problematic, depot therapy is a therapeutic alternative. The aim of this study was to compare daily versus depot treatment and factors influencing the therapeutic outcome. Newly settled refugees (n = 151) with 25(OH)D levels less than 78 nmol/L were randomised to receive daily or depot vitamin D therapy with eight weekly interval follow up to 40 weeks. Biochemical and clinical parameters were collected at each visit. Generalized Linear Mixed Models (GLMM) examined the longitudinal changes over time controlling for confounders including age, gender, treatment arm, season, country of refuge/origin and sun exposure score. Participants were aged 5.5 months to 16.0 years (75 males, 83 females). Both treatment groups achieved vitamin D sufficiency. The daily treatment group had significantly higher 25(OH)D levels at each visit post baseline and a higher proportion of participants with levels above 50 nmol/L at all time points. Time, treatment group, calcium and sun exposure score were significant predictors of 25(OH)D serum levels. Depot vitamin D therapy is an alternative to daily treatment in this at-risk group of children and adolescents in whom treatment adherence is problematic.

A review of prevalence studies of Autism Spectrum Disorder by latitude and solar irradiance impact

Autism Spectrum Disorder (ASD) is a lifelong disability with no known cause or cure. Among the suggested etiologies, is Cannell's hypothesis of a deficiency in Vitamin D the main natural source of which is Solar Ultraviolet-B (UVB) radiation. The aim in this paper is to build on this hypothesis and explore the relationship of solar irradiance of which UVB is a component, by latitude with the prevalence rates of ASD. Twenty-five reports published between 2011 and 2016 using comparable diagnostic criteria were reviewed. The results suggest a tendency for the prevalence rates of ASD to be lowest in countries near the equator and for this rate to increase as the latitude increases. These findings provide some support not just for the Vitamin D hypothesis, but also for a new proposition that along with UVB radiation, the entire solar radiation spectrum which reaches the earth, may play a role in ASD. While these results are both novel and encouraging in terms of the potential efficacy of exposure to natural sunlight, further research is warranted before results can be considered definitive, and before the implications of the findings can be implemented clinically.

Sun exposure and 25-hydroxyvitamin D3 levels in a community sample: Quantifying the association with electronic dosimeters

There is uncertainty about the amount of sun exposure required to increase low blood 25-hydroxyvitamin D (25(OH)D₃) levels, a possible disease risk factor. The study aimed to quantify the association between sun exposure and serum 25(OH)D₃ concentrations in a multiethnic community sample (n=502) living in Auckland (37°S) and Dunedin (46°S), New Zealand, aged 18-85 years. They wore electronic ultraviolet dosimeters between March and November (autumn, winter and spring) for 8 weeks to record their sun exposure. This was converted to standard erythemal doses (SEDs), corrected for clothing to generate equivalent full-body exposures, SED_EFB. Blood samples were collected at the end of weeks 4 and 8 to measure 25(OH)D₃. Median weekly SED_EFB was 0.33 during weeks 1-4 and 0.34 during weeks 5-8. Weekly exposures <0.5 SED_EFB during weeks 5-8 were associated with decreasing 25(OH)D₃ concentrations at the end of week 8. There was a non-linear association between sun exposure and 25(OH)D₃, with most of the increase in 25(OH)D₃ being at exposures <2 SED_EFB per week. This finding suggests that vitamin D status is increased by regular small sun exposures (<2 SED_EFB per week), and that greater exposures result in only small additional increases in 25(OH)D₃.

Ultraviolet radiation and effects on humans: the paradigm of maternal vitamin D production during pregnancy

Current evidence indicates that neonates born of mothers with vitamin D deficiency during pregnancy have greater risk for developing hypocalcemia, rickets and extra-skeletal disorders. Despite the classic knowledge that ultraviolet-B (UVB) exposure is the most efficient way for a future mother to obtain optimal vitamin D concentrations, no current consensus or clinical recommendations exist regarding the duration and timing of UVB exposure for pregnant women. This article offers a narrative review of available data regarding how UVB exposure affects maternal vitamin D production during pregnancy, along with a discourse on clinical implications of this public health issue. Future studies would benefit from adopting UVB exposure estimates to recommend appropriate UVB exposure to pregnant women. Doing so could provide a more holistic and practical approach in managing maternal hypovitaminosis D during pregnancy.

Vitamin D: Australian dietitian's knowledge and practices

AIM

To survey dietitians on their knowledge and practices regarding vitamin D (VitD) intake, sources, supplementation and effect on disease state.

METHODS

An online survey was disseminated to members of the Dietitian Association Australia via the weekly online state newsletter during April 2015. Response rate was 3%, with 134 respondents completing the survey. The survey included questions about knowledge and current practices. Descriptive statistics were used to analyse the results.

RESULTS

Dietitians have good knowledge regarding dietary sources of VitD and roles in the body, but there is confusion around supplement doses for treatment and prevention of deficiency and sun exposure guidelines.

CONCLUSIONS

Dietitians are well positioned to provide patients with advice on VitD supplementation and sun exposure practices, but not all are confident to provide this care. There is a need for clear and well-disseminated guidelines for VitD management by dietitians.

Vitamin D deficiency in patients with intestinal malabsorption syndromes--think in and outside the gut

There is a very high prevalence of vitamin D deficiency, which is defined by a serum level of 25-hydroxyvitamin D [25(OH)D] of lower than 20 ng/mL, in all populations of the world. Unfortunately, the prevalence of vitamin D deficiency in patients with intestinal malabsorption syndromes, including cystic fibrosis (CF), celiac disease (CD), short bowel syndrome and inflammatory bowel disease (IBD), is higher than that in the general population, indicating the presence of disease-specific causative factors. In this review, we aimed to present clinical findings to highlight the roles of insufficient exposure to sunlight and inflammation in the development of vitamin D deficiency in patients with intestinal malabsorption syndromes. Furthermore, we aimed to present experimental evidence that supported a role of vitamin D deficiency in the pathogenesis of IBD. Finally, we reviewed clinical intervention strategies aiming to normalize vitamin D status in and even to improve the conditions of patients and to discuss certain issues that needed to be addressed in future research.

Assessment of the feasibility of using sunlight exposure to obtain the recommended level of vitamin D in Canada

BACKGROUND

Endogenous vitamin D synthesis can be affected by a number of variables, including skin colour, amount of skin exposed and levels of ultraviolet radiation. The objective of this study was to assess the feasibility of using only sunlight exposure in Canada to meet the daily recommended level of vitamin D, given differences in these variables and adherence to guidelines for sun protection.

METHODS

Ultraviolet index data for 13 Canadian sites were obtained from Environment Canada. The sun exposure times required to synthesize 1000 IU of vitamin D in fair- and dark-skinned people who exposed either 1/4 or 1/8 of their body surface area to the sun were calculated for each hour of the year. These times were then classified according to whether the ultraviolet index was 3 or more (when sun protection is advised) or less than 3.

RESULTS

During the fall and winter months and in the more northern sites, ultraviolet radiation levels were too low for all skin types to use sun exposure alone to obtain enough vitamin D within one time period. The required exposure time became longer when a smaller surface area was exposed. For people with darker skin, it can be difficult even in the summer to find opportunities outside of when sun protection is advised to use sunlight to obtain the recommended dose of vitamin D.

INTERPRETATION

Although sun exposure is an important source of vitamin D, Canadians should look to other safe sources to meet the body's vitamin D requirements throughout the year.

Ultraviolet index and location are important determinants of vitamin D status in people with human immunodeficiency virus

This study aimed to document the vitamin D status of HIV-infected individuals across a wide latitude range in one country and to examine associated risk factors for low vitamin D. Using data from patients attending four HIV specialist clinics across a wide latitude range in Australia, we constructed logistic regression models to investigate risk factors associated with 25(OH)D < 75 nmol L(-1). 1788 patients were included; 87% were male, 76% Caucasian and 72% on antiretroviral therapy. The proportion with 25(OH)D < 50 nmol L(-1) was 27%, and <75 nmol L(-1) was 54%. Living in Melbourne compared with Cairns (adjusted odds ratio (aOR) 3.30; 95% CI 2.18, 4.99, P < 0.001) and non-Caucasian origin (aOR 2.82, 95% CI 2.12, 3.75, P < 0.001) was associated with an increased risk, while extreme UV index compared with low UV index was associated with a reduced risk (aOR 0.33; 95% CI 0.20, 0.55, P < 0.001) of 25(OH)D < 75 nmol L(-1). In those with biochemistry available (n = 1117), antiretroviral therapy was associated with 25(OH)D < 75 nmol L(-1); however, this association was modified by serum cholesterol status. Location and UV index were the strongest factors associated with 25(OH)D < 75 nmol L(-1). Cholesterol, the product of an alternative steroid pathway with a common precursor steroid, modified the effect of antiretroviral therapy on serum 25(OH)D.

Vitamin d supplementation in australia: implications for the development of supplementation guidelines

High rates of vitamin D deficiency and testing have been reported in Australia, yet there are few reports regarding vitamin D supplement use. Australian wholesale sales data was obtained for vitamin D supplements for the period 2000-2011. There has been a threefold increase in supplement sales over the past decade, whereby over A$94 million supplements containing vitamin D in Australia were sold during the year 2010. There were eighty-nine manufacturers that produce a variety of 195 vitamin D products. The amount of vitamin D in these products varies considerably, from 40 to 1000 IU per unit, although supplements containing only vitamin D had the highest amount of vitamin D. There was a trend for sales to increase in winter months. Given the potential public health benefits of vitamin D, there is an urgent need for a better understanding of supplementation use and for the development of supplementation.

Latitude, sunlight, vitamin D, and childhood food allergy/anaphylaxis

Vitamin D is widely known for its role in bone metabolism, but this sterol hormone also has important immunomodulatory properties. Vitamin D is produced by the conversion of D3 in the skin following UVB exposure, or after ingestion of D2 or D3. At the extremes of latitude, there is insufficient UVB intensity in the autumn and winter months for adequate synthesis of vitamin D to occur. Growing evidence implicates vitamin D deficiency in early life in the pathogenesis of nonskeletal disorders (e. g., type 1 diabetes and multiple sclerosis) and, more recently, atopic disorders. Several studies have reported higher rates of food allergy/anaphylaxis or proxy measures at higher absolute latitudes. Although causality remains to be determined, these studies suggest a possible role for sunlight and/or vitamin D in the pathogenesis of food allergy/anaphylaxis.

Make vitamin D while the sun shines, take supplements when it doesn't: a longitudinal, observational study of older adults in Tasmania, Australia

Low vitamin D status has been associated with a number of chronic conditions, particularly in older adults. The aim of this study was to identify how best to maintain optimum vitamin D status throughout the year in this high-risk population. The main objectives of the study were to assess seasonal vitamin D status; identify the main determinants of vitamin D status; determine if taking part in the study led to alterations in participant behaviour and vitamin D status. A longitudinal design across four consecutive seasons observed ninety-one 60–85 year old community-dwelling adults in Tasmania (41π S) over 13 consecutive months, with a follow-up assessment at next winter's end. Associations between solar UVB exposure, sun protection behaviours, dietary and supplemental vitamin D with serum 25(OH)D concentrations were assessed. Variation in serum 25(OH)D demonstrated an identical pattern to solar UVB, lagging 8–10 weeks. Serum 25(OH)D was positively associated with summer UVB (mean 15.9 nmol/L; 95%CI 11.8–19.9 nmol/L, p<0.001) and vitamin D supplementation (100–600 IU/day: 95%CI 10.2 nmol/L; 0.8–19.6 nmol/L; p = 0.03; 800 IU/day: 21.0 nmol/L; 95%CI 8.1–34.0 nmol/L; p = 0.001). Seasonal variation in serum 25(OH)D was greatly diminished in supplement users. The most common alteration in participant behaviour after the study was ingesting vitamin D supplements. Post-study vitamin D supplementation ℘800 IU/day was seven times more likely than during the study resulting in mean difference in serum 25(OH)D between supplement and non-supplement users of 30.1 nmol/L (95%CI 19.4–40.8 nmol/L; p<0.001). The main limitation was homogeneity of participant ethnicity. Solar exposure in summer and ingestion of vitamin D supplements in other seasons are the most effective ways of achieving and maintaining year-round vitamin D sufficiency in older adults in the Southern hemisphere. Vitamin D supplementation has greatest effect on vitamin D status if ingested during and after winter, i.e. between the autumn and spring equinoxes.