Effects of sun protection on serum vitamin D deficiency
10.1111/phpp.12838
Shrey Patel BS1, Shiv Patel BA2, Rohan M. Shah BA2, Sahil Doshi BA2, Sareena Shah3, Peter A. Lio MD2
1 University of Miami Miller School of Medicine, Miami, FL, USA 2Northwestern University Feinberg School of Medicine, Chicago, IL, USA 3 University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA
Introduction
Engagement in sun protection behaviors is broadly recommended to prevent the development of UVR-related conditions such as skin cancer.1 These behaviors may come in the form of sun avoidance, use of protective clothing, and application of sunscreen. Weighing the risks and benefits of sun exposure is a particularly important consideration in sunburn susceptible Caucasian populations as overlap in the International Commission on Illumination action spectra of erythema with that of pre-vitamin D synthesis generates concern for sunscreen use compromising vitamin D synthesis.2,3 There are mixed reports on the impact of sun protection behaviors and their influence on vitamin D status.4,5 Vitamin D deficiency is associated with an increased risk of bone fractures, autoimmune disease, and cancer, however, supplementation may manage vitamin D deficiency while promoting sun protection habits, though the literature to support such an effort is unclear.6
Our study aims to investigate the relationship between engagement in sun protection behaviors and vitamin D deficiency using serum 25-hydroxyvitamin D data from the 2013-2018 US National Health and Nutrition Examination Surveys (NHANES).
Methods
Our investigation sourced data from the 2013-2018 cycles of the NHANES, which collects nationally representative health data pertaining to the civilian, non-institutionalized population of the United States in 2-year intervals.7 Non-Hispanic White respondents who underwent the laboratory examination and provided valid responses to items in the dermatology questionnaire and dietary interview were included in the study. Sun protection behaviors were evaluated through the questionnaires: staying in the shade, wearing long-sleeved shirts, and using sunscreen. Participants’ engagement in these behaviors was classified as “frequent” when reported as “always” or “most of the time,” as “occasional” when reported as “sometimes” or “rarely,” and as “never” when no engagement was reported. Dietary interview responses were used to measure vitamin D supplementation (pg) over a 30-day period. Liquid chromatography- tandem mass spectrometry was used to measure serum 25(OH)D levels for each participant. The season of each participant’s interview was recorded as 6-month time periods: November 1-April 30 or May 1-October 31. Demographic data were also collected. As the NHANES reports publicly accessible deidentified data, institutional review board approval was not required. Informed consent was obtained when the data was originally collected.
A cross-sectional analysis was conducted based on responses to the NHANES dermatology questionnaire, dietary interview, and laboratory data. The sample was weighted to account for the complex survey design of the NHANES, accounting for oversampling, nonresponse, and post-stratification adjustment to match population control totals from the US Census Bureau. All analyses were informed by the analytic guidelines published by the CDC.8 The primary outcome measure of vitamin D deficiency was defined as 25(OH)D concentration <50 nmol/L. Multiple logistic regression models assessed the odds of vitamin D deficiency after adjusting for age, race, gender, vitamin D supplementation, and season of the lab examination. Adjusted odds ratios, 95% confidence intervals, and p-values were computed from the multiple logistic regression models. A priori significance was set at P<0.05.
Results
A total of 1,213 participants met the inclusion criteria for the study. The weighted sample was more commonly female (54.9%), aged 43.1 years, and occasionally engaged in sunscreen use (44.4%), wearing long-sleeved shirts (53.9%), and staying in the shade (67.8%). Sample demographics are reported in Table 1. Wearing long-sleeved shirts was significantly associated with vitamin D deficiency (aOR=3.32; 95% CI:1.26-8.76; P=0.017), though no other forms of sun protection demonstrated similar odds. Vitamin D supplementation > 20 ng over a 30-day period reduced the odds of vitamin D deficiency (aOR=0.33; 95% CL0.13-0.81; P=0.018). Participants interviewed between May 1-October 31 were less likely to be vitamin D deficient (aOR = 0.28; 95% CL0.13-0.57; P=0.001). Weighted odds of vitamin D deficiency are reported in Table 2.
Discussion
Engagement in sun protection behaviors was not associated with vitamin D deficiency when accounting for vitamin D supplement intake, with the exception of frequently wearing long-sleeve clothing. Limitations in sample size, seasonal impact being limited to 6-month periods, and inconsistencies in individual sun protection practices contribute to variations in UVR exposure.
Our findings suggest no direct linkage between sun protection and vitamin D health in non-Hispanic white US adults, offering encouraging evidence to contribute to the growing body of literature supporting sun-protective practices. As such, providers should aim to recommend sun protection alongside vitamin D supplementation to prevent the development of UVR-related conditions and maintain optimal health among patients.
VitaminDWiki - Vitamin D produced by hands and face is 8X more than elsewhere – Feb 2018
See also Vitamin D production after UVB exposure – A comparison of exposed skin regions – Feb 2015