Sun protection and vitamin D status in an Australian subtropical community.

OBJECTIVE: Claims have been made that sun protection may negatively affect vitamin D status, but very few data are available about whether this applies to people in uncontrolled settings. METHOD: In 1996 we measured 25(OH)-vitamin D concentrations in 1113 adults in Nambour, a subtropical community, who reported their concurrent sun protection behaviours in a skin cancer prevention trial. Estimates were adjusted for time outdoors, vitamin D intake and other factors known to affect vitamin D status. RESULTS: Persons who tended to stay in the shade had lower vitamin D levels than those who never stayed in the shade (62.5 vs. 68.8 nmol/L respectively, p=0.01), and this association remained in persons who spent less than 50% (p=0.02) but not in those who spent more than 50% of their time outdoors. Wearing a hat, long sleeves, sunglasses and use of sunscreen or umbrella were not associated with vitamin D status after adjustments, including after stratification by time outdoors. CONCLUSION: Sun protection behaviour to reduce the risk of skin cancer can be maintained without affecting vitamin D serum status, although consistently seeking shade when spending less than 50% of daytime outdoors is associated with lower vitamin D levels.

Repeatability and reproducibility of multiparametric magnetic resonance imaging of the liver.

As the burden of liver disease reaches epidemic levels, there is a high unmet medical need to develop robust, accurate and reproducible non-invasive methods to quantify liver tissue characteristics for use in clinical development and ultimately in clinical practice. This prospective cross-sectional study systematically examines the repeatability and reproducibility of iron-corrected T1 (cT1), T2*, and hepatic proton density fat fraction (PDFF) quantification with multiparametric MRI across different field strengths, scanner manufacturers and models. 61 adult participants with mixed liver disease aetiology and those without any history of liver disease underwent multiparametric MRI on combinations of 5 scanner models from two manufacturers (Siemens and Philips) at different field strengths (1.5T and 3T). We report high repeatability and reproducibility across different field strengths, manufacturers, and scanner models in standardized cT1 (repeatability CoV: 1.7%, bias -7.5ms, 95% LoA of -53.6 ms to 38.5 ms; reproducibility CoV 3.3%, bias 6.5 ms, 95% LoA of -76.3 to 89.2 ms) and T2* (repeatability CoV: 5.5%, bias -0.18 ms, 95% LoA -5.41 to 5.05 ms; reproducibility CoV 6.6%, bias -1.7 ms, 95% LoA -6.61 to 3.15 ms) in human measurements. PDFF repeatability (0.8%) and reproducibility (0.75%) coefficients showed high precision of this metric. Similar precision was observed in phantom measurements. Inspection of the ICC model indicated that most of the variance in cT1 could be accounted for by study participants (ICC = 0.91), with minimal contribution from technical differences. We demonstrate that multiparametric MRI is a non-invasive, repeatable and reproducible method for quantifying liver tissue characteristics across manufacturers (Philips and Siemens) and field strengths (1.5T and 3T).

Vitamin D intake in Australian adults and the modeled effects of milk and breakfast cereal fortification.

OBJECTIVE: Vitamin D intake from foods or supplements is a safe and attractive means to improve vitamin D status of populations. The aim of this study was to help identify population subgroups that would benefit most from efforts to increase intake. To do so, we investigated which personal characteristics are associated with vitamin D intake in an Australian population and modeled possible effects of expanded food fortification practices. METHODS: We investigated vitamin D intake in a population-based random sample of 785 adults, using a validated food frequency questionnaire, and assessed associations with personal and behavioral characteristics. We identified vitamin D food sources and modeled the hypothetical effects of blanket fortification of milk and breakfast cereals. RESULTS: Average total vitamin D intake was 4.4 (±4.0) µg/g and below adequate intake for most participants in all age and sex subgroups. Higher intake was associated with being female, having a serious medical condition, energy intake below the median, and vitamin D supplement use (all P < 0.05). The "meat, fish, and eggs" food group contributed most to total vitamin D intake (51%), followed by dairy products and related foods (43%). If all milk and breakfast cereals were to be fortified with vitamin D, the average intake of vitamin D from foods would increase from 3.6 (±2.4) µg/d to 6.3 (±3.2) µg/d, with similar increases in all age and sex subgroups. CONCLUSIONS: Vitamin D intake in Australia is generally below recommended levels, and few personal characteristics help to identify subgroups with low intake. Blanket vitamin D fortification of milk and breakfast cereals would substantially increase average vitamin D intake in Australian adults of all ages.