Michael G. Kimlin

Vitamin D Intake Needed to Maintain Target Serum 25-Hydroxyvitamin D Concentrations in Participants with Low Sun Exposure and Dark Skin Pigmentation Is Substantially Higher Than Current Recommendations

Cutaneous cholecalciferol synthesis has not been considered in making recommendations for vitamin D intake. Our objective was to model the effects of sun exposure, vitamin D intake, and skin reflectance (pigmentation) on serum 25-hydroxyvitamin D (25[OH]D) in young adults with a wide range of skin reflectance and sun exposure. Four cohorts of participants (n = 72 total) were studied for 7-8 wk in the fall, winter, spring, and summer in Davis, CA [38.5 degrees N, 121.7 degrees W, Elev. 49 ft (15 m)]. Skin reflectance was measured using a spectrophotometer, vitamin D intake using food records, and sun exposure using polysulfone dosimeter badges. A multiple regression model (R(2) = 0.55; P < 0.0001) was developed and used to predict the serum 25(OH)D concentration for participants with low [median for African ancestry (AA)] and high [median for European ancestry (EA)] skin reflectance and with low [20th percentile, approximately 20 min/d, approximately 18% body surface area (BSA) exposed] and high (80th percentile, approximately 90 min/d, approximately 35% BSA exposed) sun exposure, assuming an intake of 200 iu/d (5 ug/d). Predicted serum 25(OH)D concentrations for AA individuals with low and high sun exposure in the winter were 24 and 42 nmol/L and in the summer were 40 and 60 nmol/L. Corresponding values for EA individuals were 35 and 60 nmol/L in the winter and in the summer were 58 and 85 nmol/L. To achieve 25(OH)D > or =75 nmol/L, we estimate that EA individuals with high sun exposure need 1300 iu/d vitamin D intake in the winter and AA individuals with low sun exposure need 2100-3100 iu/d year-round.

Quantification of personal solar UV exposure of outdoor workers, indoor workers and adolescents at two locations in Southeast Queensland

Quantification of human exposure to solar ultraviolet (UV) radiation at two locations was performed to study the effect of occupation (outdoor workers, schoolchildren and home workers) and location on personal UV exposure. The study took place on 13 and 14 February 1997 in Toowoomba (27.5°S, 151.9°E) and Brisbane (27.4°S, 153.1°E) in Southeast Queensland, Australia. From the data collected by calibrated ambient UV monitoring stations located in Toowoomba and Brisbane, Toowoomba received 16% more UVB (280–320 nm) than Brisbane from 07:00 to 17:00 Australian Eastern Standard Time (EST) on the 13 February, 1997 and 10% more UVB on the 14 February 1997. All groups, regardless of occupation, in this study received a median erythemal UV exposure of over 2 MED on the shoulder over the 2 day period. The highest median erythemal UV exposure to the shoulder over the 2 day period was 6 MED in Toowoomba outdoor workers. The median 2 day erythemal exposure to the shoulder was 33% higher in Toowoomba than in Brisbane for the outdoor workers, 50% higher in Toowoomba compared to Brisbane for the schoolchildren and 25% higher in Toowoomba than Brisbane for the home workers.

UV index climatology over the United States and Canada from ground‐based and satellite estimates

[1] Long-term monthly mean UV index values for Canada and the United States were calculated using information from two sources: from noon erythemal UV estimated from Total Ozone Mapping Spectrometer (TOMS) total ozone and reflectivity data and from UV index values derived from observations of global solar radiation, total ozone, dew point, and snow cover. The results are presented as monthly maps of mean noon UV index values. Mean UV index values in summer range from 1.5 in the Arctic to 11.5 over southern Texas. Both climatologies were validated against spectral UV irradiance measurements made by Brewer spectrophotometers. With snow on the ground the TOMSbased data underestimate UV by up to 60% with respect to Brewer measurements and UV derived from global solar radiation and other parameters. In summer, TOMS UV index climatology values are from 10 to 30% higher than those derived from global solar radiation and other parameters. The difference is probably related to aerosol absorption and pollution effects in the lower troposphere that are not currently detected from space. For 21 of 28 midlatitude Brewer sites, long-term mean summer UV measured values and UV derived from global solar radiation and other parameters agree to within +5 to 7%. The remaining seven sites are located in ‘‘clean’’ environments where TOMS estimates agree with Brewer measurements while UV derived from global solar radiation and other parameters is 10–13% lower. Brewer data also demonstrate that clean and ‘‘typical’’ sites can be as little as 70–120 km apart. INDEX TERMS: 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation; 3359 Meteorology and Atmospheric Dynamics: Radiative processes; 0394 Atmospheric Composition and Structure: Instruments and techniques; 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); KEYWORDS: UV index, Brewer, TOMS, pyranometer, climatology, ozone

Vitamin D in health and disease: an insight into traditional functions and new roles for the ‘sunshine vitamin’

Vitamin D is unique among the vitamins in that man can synthesise it via the action of UV radiation upon the skin. This combined with its ability to act on specific target tissues via vitamin D receptors (VDR) make its classification as a steroid hormone more appropriate. While vitamin D deficiency is a recognised problem in some northern latitude countries, recent studies have shown that even in sunny countries, such as Australia, vitamin D deficiency may be more prevalent than first thought. Vitamin D is most well known for its role in bone health; however, the discovery of VDR on a wide variety of tissue types has also opened up roles for vitamin D far beyond traditional bone health. These include possible associations with autoimmune diseases such as multiple sclerosis and inflammatory bowel diseases, cancer, CVD and muscle strength. First, this paper presents an overview of the two sources of vitamin D: exposure to UVB radiation and food sources of vitamin D, with particular focus on both Australian and international studies on dietary vitamin D intake and national fortification strategies. Second, the paper reviews recent epidemiological and experimental evidence linking vitamin D and its role in health and disease for the major conditions linked to suboptimal vitamin D, while identifying significant gaps in the research and possible future directions for research.

Vitamin D and sun protection: The impact of mixed public health messages in Australia

Exposure of the skin to sunlight can cause skin cancer and is also necessary for cutaneous Vitamin D production. Media reports have highlighted the purported health benefits of Vitamin D. Our aim was to examine attitudes and behaviours related to sun protection and Vitamin D. A cross‐sectional study of 2,001 residents in Queensland, Australia, aged 20–70 years was undertaken. Information collected included the following: skin cancer risk factors; perceptions about levels of sun exposure required to maintain Vitamin D; belief that sun protection increases risk of Vitamin D deficiency; intention, and actual change in sun protection practices for adults and children. Multivariate models examined predictors of attitudinal and behavioural change. One‐third (32%) believed a fair‐skinned adult, and 31% thought a child required at least 30 min/day in summer sun to maintain Vitamin D levels. Reductions in sun protection were reported by 21% of adults and 14% of children. Factors associated with the belief that sun protection may result in not obtaining enough Vitamin D included age of ≥60 years (OR = 1.35, 95% CI 1.09–1.66) and having skin that tanned easily (OR = 1.96, 95% CI 1.38–2.78). Participants from low‐income households, and those who frequently used sun‐protective clothing were more likely to have reduced sun protection practices (OR = 1.33, 95% CI 1.10–1.73 and OR = 1.73, 95% CI 1.36–2.20, respectively). This study provides evidence of reductions in sun protection practices in a population living in a high UV environment. There is an urgent need to refocus messages regarding sun exposure and for continued sun protection practices.

Diffuse component of solar ultraviolet radiation in tree shade.

The first set of quantitative data of diffuse erythemal UV and UV-A radiation in tree shade at a sub-tropical Southern Hemisphere latitude is presented. Over the summer, approximately 60% of the erythemal UV radiation in tree shade is due to the diffuse component. Similarly, approximately 56% of the UV-A radiation in tree shade is due to the diffuse component. In tree shade these diffuse UV percentages are relatively constant from the morning to noon to afternoon periods. In comparison, in full sun, there is a decrease in the percentage of diffuse UV from morning to noon to afternoon. The exposures to diffuse UV on a horizontal plane in tree shade between 9:00 EST and 15:00 EST are of the order of 4 MED (minimum erythemal dose) and 14 J cm(-2) for erythemal UV and UV-A, respectively. The high diffuse UV component in the shade may result in high UV exposures not only to unprotected parts of the body on a horizontal plane, but also in equally high UV irradiances to parts of the body, including the eyes and face, that are not UV protected.

The Contributions of Solar Ultraviolet Radiation Exposure and Other Determinants to Serum 25-Hydroxyvitamin D Concentrations in Australian Adults: The AusD Study

The Quantitative Assessment of Solar UV [ultraviolet] Exposure for Vitamin D Synthesis in Australian Adults (AusD) Study aimed to better define the relationship between sun exposure and serum 25-hydroxyvitamin D (25(OH)D) concentration. Cross-sectional data were collected between May 2009 and December 2010 from 1,002 participants aged 18-75 years in 4 Australian sites spanning 24° of latitude. Participants completed the following: 1) questionnaires on sun exposure, dietary vitamin D intake, and vitamin D supplementation; 2) 10 days of personal ultraviolet radiation dosimetry; 3) a sun exposure and physical activity diary; and 4) clinical measurements and blood collection for 25(OH)D determination. Our multiple regression model described 40% of the variance in 25(OH)D concentration; modifiable behavioral factors contributed 52% of the explained variance, and environmental and demographic or constitutional variables contributed 38% and 10%, respectively. The amount of skin exposed was the single strongest contributor to the explained variance (27%), followed by location (20%), season (17%), personal ultraviolet radiation exposure (8%), vitamin D supplementation (7%), body mass index (weight (kg)/height (m)(2)) (4%), and physical activity (4%). Modifiable behavioral factors strongly influence serum 25(OH)D concentrations in Australian adults. In addition, latitude was a strong determinant of the relative contribution of different behavioral factors.

Sunlight and Other Determinants of Circulating 25-Hydroxyvitamin D Levels in Black and White Participants in a Nationwide US Study

Circulating 25-hydroxyvitamin D (25(OH)D), a marker for vitamin D status, is associated with bone health and possibly cancers and other diseases; yet, the determinants of 25(OH)D status, particularly ultraviolet radiation (UVR) exposure, are poorly understood. Determinants of 25(OH)D were analyzed in a subcohort of 1,500 participants of the US Radiologic Technologists (USRT) Study that included whites (n = 842), blacks (n = 646), and people of other races/ethnicities (n = 12). Participants were recruited monthly (2008-2009) across age, sex, race, and ambient UVR level groups. Questionnaires addressing UVR and other exposures were generally completed within 9 days of blood collection. The relation between potential determinants and 25(OH)D levels was examined through regression analysis in a random two-thirds sample and validated in the remaining one third. In the regression model for the full study population, age, race, body mass index, some seasons, hours outdoors being physically active, and vitamin D supplement use were associated with 25(OH)D levels. In whites, generally, the same factors were explanatory. In blacks, only age and vitamin D supplement use predicted 25(OH)D concentrations. In the full population, determinants accounted for 25% of circulating 25(OH)D variability, with similar correlations for subgroups. Despite detailed data on UVR and other factors near the time of blood collection, the ability to explain 25(OH)D was modest.

Evaluation of differences in ultraviolet exposure during weekend and weekday activities.

The weekday UV exposures to anatomical sites were evaluated for outdoor workers, home workers, adolescents, indoor workers, school staff and students in south-east Queensland, Australia. Additionally, the UV exposures at weekends of school staff, school students, indoor workers and outdoor workers were evaluated. The weekday exposures per day ranged from 1.0 to 11.0 SED for winter to summer respectively. During spring, the ratios of the personal exposures divided by the ambient exposures at the weekend to the personal exposures divided by the ambient exposures on the weekdays to the neck, hand and left arm were at least 3.4, 2.0 and 0.67 for the indoor workers, school staff and students and outdoor workers respectively. The same ratios for the erythemal UV exposures over the year, estimated from the exposures on four days in each of the four seasons, were at least 2.3 for the school staff and at least 1.3 for the 13 to 19 year old school students. These results reinforce the importance of targeting prevention programmes to both weekend and weekday exposures.

Building healthy bones throughout life: an evidence-informed strategy to prevent osteoporosis in Australia

Free to read on journal website (may need to create free account first) Osteoporosis imposes a tremendous burden on Australia : 1.2 million Australians have osteoporosis and 6.3 million have Osteopenia. In the 2007-08 financial year, 82000 Australians suffered fragility fractures, of Which >17000 were hip fractures. In the 2000-01 financial year, direct costs were estimated at