Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure

Effect of preoperative vitamin D on postoperative atrial fibrillation incidence after coronary artery bypass grafting

BACKGROUND

Post-operative atrial fibrillation (POAF) is associated with adverse long-term cardiovascular events.

OBJECTIVES

This study investigated the effects of a high-dose vitamin D administered preoperatively on the postoperative atrial fibrillation (POAF) incidence in patients with vitamin D deficiency following coronary artery bypass grafting (CABG) surgery.

METHODS

This randomized controlled clinical trial was conducted on 246 CABG patients with vitamin D deficiency. All patients were randomly divided into intervention and control groups including 123 cases for each group. In the intervention group, from 3 days before surgery, they received a daily dose of 150,000 units of vitamin D orally (50,000 units of Vit D tablet three times a day) and the patients in the control group received placebo tablets before surgery. All patients in the intervention group were assessed continuously for the occurrence of POAF during the recovery period.

RESULTS

In terms of gender, age, and BMI there were no significant differences between intervention and control groups. Our findings showed that the use of vitamin D supplements did not cause a significant change in the duration of intubation and hospitalization. The ratio of POAF following CABG surgery in the control and treatment groups was 26% and 11.4%, respectively (odds ratio = 0.36; 95% CI = 0.18-0.72; P = 0.003).

CONCLUSIONS

Our findings revealed that high-dose vitamin D supplementation before CABG surgery significantly reduced the incidence of POAF. Further multicenter randomized trials with larger sample sizes are certainly warranted to confirm our results.

The Global Prevalence of Vitamin D Deficiency and Insufficiency in Patients with Multiple Myeloma: A Systematic Review and Meta-Analysis

BACKGROUND

Multiple myeloma (MM) is a hematological malignancy characterized by the exponential growth of malignant plasma cells. Individuals diagnosed with MM exhibit a deficiency in vitamin D and may suffer fatigue, a loss of muscular strength, persistent musculoskeletal aches, and pain. The objective of this systematic review and meta-analysis is to determine the prevalence of vitamin D insufficiency and deficiency in individuals diagnosed with MM.

METHODS

We searched five electronic databases using relevant keywords. The quality of the included studies was evaluated using the critical appraisal tool developed by the Joanna Briggs Institute. We employed a random-effects model and presented the findings in the form of percentages accompanied by 95% confidence intervals (CI). This protocol has been officially registered in PROSPERO under the registration number CRD42021248710.

RESULTS

The meta-analysis comprised a total of eighteen studies and found that, among patients with MM, the occurrence of serum vitamin D deficiency and insufficiency was 39.4% (95% CI: 25.8 to 52.9, n = 3746) and 34.1% (95% CI: 20.9 to 47.2, n = 3559), respectively. The findings indicate that a greater proportion of newly diagnosed patients exhibited vitamin D deficiency and insufficiency, with rates of 43.0% and 41.6%, respectively, compared to those receiving treatment (rates of 41.6% and 32.3%, respectively). The findings of the sensitivity analyses were consistent, and most of the studies (72.2%) were deemed to be of high quality. The results of Egger's test indicated the absence of publication bias.

CONCLUSIONS

Patients diagnosed with MM have been found to exhibit significantly elevated levels of both vitamin D deficiency and insufficiency. Therefore, it is recommended to consider vitamin D testing as an additional parameter in the current criteria for the clinical evaluation of MM.

Ultraviolet light induces mechanical and structural changes in full thickness human skin

While the detrimental health effects of prolonged ultraviolet (UV) irradiation on skin health have been widely accepted, the biomechanical process by which photoaging occurs and the relative effects of irradiation with different UV ranges on skin biomechanics have remained relatively unexplored. In this study, the effects of UV-induced photoageing are explored by quantifying the changes in the mechanical properties of full-thickness human skin irradiated with UVA and UVB light for incident dosages up to 1600 J/cm2. Mechanical testing of skin samples excised parallel and perpendicular to the predominant collagen fiber orientation show a rise in the fractional relative difference of elastic modulus, fracture stress, and toughness with increased UV irradiation. These changes become significant with UVA incident dosages of 1200 J/cm2 for samples excised both parallel and perpendicular to the dominant collagen fiber orientation. However, while mechanical changes occur in samples aligned with the collagen orientation at UVB dosages of 1200 J/cm2, statistical differences in samples perpendicular to the collagen orientation emerge only for UVB dosages of 1600 J/cm2. No notable or consistent trend is observed for the fracture strain. Analyses of toughness changes with maximum absorbed dosage reveals that no one UV range is more impactful in inducing mechanical property changes, but rather these changes scale with maximum absorbed energy. Evaluation of the structural characteristics of collagen further reveals an increase in collagen fiber bundle density with UV irradiation, but not collagen tortuosity, potentially linking mechanical changes to altered microstructure.

The Effect of Sunlight Exposure on Vitamin D Status in Countries of Low and High Latitudes: A Systematic Literature Review

PURPOSE OF THE REVIEW

To conduct a systematic review of studies to investigate the association between climate and vitamin D in humans.

RECENT FINDINGS

There is growing interest in the association between the environment and vitamin D, but robust methods to understand this relationship are lacking. Studies focus mainly on seasonality and latitude. Research quantifying sunlight exposure necessary for adequate vitamin D synthesis in people with darker skin color and those people living at low latitudes are scarce, as are studies in urban populations that may have limited opportunity for sunlight exposure. There are gaps regarding values and timing of exposure to UV radiation required for adequate vitamin D synthesis considering skin color, geography, climate, and local irradiation. Nature-based solutions (NbS) that can mitigate climate change will become increasingly important for preventing hypovitaminosis D. For example, tree-shaded spaces might encourage more participation in outside activities and thereby favor vitamin D synthesis by the skin.

The Effect of Vitamin D Level on Parathyroid Hormone and Alkaline Phosphatase

Over the years, we have noticed in our clinical practice that patients with 25-hydroxyvitamin D (25OHD) levels below 15 ng/mL are more symptomatic than those with higher levels. The aim of this research is to investigate changes in both parathyroid hormone (PTH) and alkaline phosphatase (ALP) at different vitamin D levels to determine if lower vitamin D levels are associated with more severe changes in PTH and ALP, which may explain the presence and severity of symptoms at those lower 25OHD levels. We looked for correlations between 25OHD level, PTH, and ALP in 1311 samples between 2015 and 2019 at our endocrine clinic to determine if vitamin D level correlates with changes in PTH and ALP. We further categorized vitamin D deficiency levels into three categories based on the severity of the reported symptoms. As expected, there were inverse but significant correlations between 25OHD, PTH, and ALP. The lower the 25OHD, the higher the PTH and ALP levels. When 25OHD was below 10 ng/mL, PTH was increased in 65% of the samples and ALP was elevated in 21% of the samples; however, PTH and ALP were normal in 70% and 87%, respectively, of patients with 25OHD levels between 15 < 20 ng/mL. The results support our clinical observations since most of the patients with 25OHD greater than 15 ng/mL had normal PTH and ALP, which may explain the lack of symptoms in these patients.

Statistical power in vitamin D randomized control trials investigating biomarkers as continuous outcomes

It has long been suspected that mean vitamin D level and differences among individuals in the population might deteriorate power in vitamin D randomised controlled trials (RCTs). However, standard statistical planning tools cannot accommodate these considerations. Here, to accommodate the large within-person and between-people heterogeneity in naturally fluctuating 25-hydroxyvitamin D (25OHD) concentration, a simulation based approach was used to investigate the power and sample size requirements in vitamin D supplementation RCTs looking at the proportion of regulatory T cells, %Tregs, as a continuous outcome. A range of sample sizes, mean increases in 25OHD in the intervention arm, and population 25OHD heterogeneity were tested. We found that in a population with a mean 25OHD of 50▒nmol/L and moderate heterogeneity in 25OHD (defined as inter-quartile range IQR = 20), sample size of approximately 1000 participants per arm is required to achieve 80% power if 25OHD increased by 10▒nmol/L in the intervention arm, compared to 250, < 100 and < 50 participants per arm if this increase was 20▒nmol/L, 40▒nmol/L or 60▒nmol/L, respectively. Thus we conclude that the increase in 25OHD in the intervention arm and population heterogeneity impact the power of vitamin D RCTs substantially. Sample size determination through simulation is a powerful approach for non-standard trials, and the work presented can easily be adopted to other intervention-outcome pairs.

The Skin We Live in: Pigmentation Traits and Tanning Behaviour in British Young Adults, an Observational and Genetically-Informed Study

Skin cancer incidence has been increasing worldwide, representing a particularly high burden for populations of European ancestry. Outdoor and indoor tanning using ultraviolet (UV) radiation devices are major risk factors for skin cancer. While tanning behaviours can be modified by targeted interventions to reduce skin cancer rates, there is insufficient evidence on the motivations for tanning preferences and their relationship with pigmentation phenotypes. The present observational and genetically-informed study investigates motives for tanning and the role that pigmentation phenotypes play on outdoor and indoor tanning behaviour in British young adults. This study included 3722 participants from the Avon Longitudinal Study of Parents and Children in South West England, with data on pigmentation features, tanning ability and preferences, and SNP genotypes. Liking to tan and outdoor tanning were strongly influenced by pigmentary traits and tanning ability. However, the association of these phenotypes with UV indoor tanning was weaker. Our results provide evidence to support the implementation of skin cancer preventative interventions that consider individual biological characteristics and motives for undergoing outdoor and indoor tanning.

Lipid Nanomaterials for Targeted Delivery of Dermocosmetic Ingredients: Advances in Photoprotection and Skin Anti-Aging

Despite the health benefits of the sun, overexposure to solar radiation without proper precautions can cause irreversible damage to exposed skin. In the search for balance between the risks and benefits of exposure to solar radiation in human health, a technological alternative was found, the incorporation of photoprotective products in lipid nanoparticulate systems for topical application. These nanometric systems have demonstrated several advantages when used as adjuvants in photoprotection compared to chemical and/or physical sunscreens alone. The increase in the sun protection factor (SPF), photostability and UV action spectrum are parameters that have benefited from the application of these systems in order to increase the effectiveness and safety of photoprotective formulations containing organic and/or inorganic sunscreens.

Serum Vitamin D Insufficiency in Hospitalized Full-Term Neonates at a Tertiary Hospital in Eastern China

OBJECTIVE

This study explored the status of serum vitamin D in hospitalized full-term neonates at a tertiary hospital in eastern China.

METHODS

A prospective study was conducted among 471 hospitalized full-term neonates at the Children's Hospital of Soochow University between January 1 and June 20, 2020. Perinatal clinical data, serum 25-hydroxyvitamin D (25(OH)D₃), laboratory examinations, serum calcium levels, and immune function were obtained and analyzed. We explored and analyzed the risk factors for vitamin D insufficiency or deficiency, and we also attempted to determine correlations between vitamin D and its influence on immunity.

RESULTS

The mean serum 25(OH)D₃ was 33.65±6.07ng/ml.The prevalence of vitamin D insufficiency was 28.24%,vitamin D sufficiency was 71.76%, there was no vitamin D deficiency. The serum 25-(OH)D₃ in singleton neonate was higher than twins or multiple infants (t = -10.918, P = 0.000). The serum 25-(OH)D₃ were higher in neonates who born in spring and summer than in winter (H = 13.443, P = 0.001). The serum 25-(OH)D₃ in appropriate for gestational age (AGA) and large for gestational age (LGA) neonates were higher than small for gestational age (SGA) (H = 7.686, P = 0.021). The serum 25-(OH)D₃ were higher in neonates whose mothers had no underlying diseases than those with certain immunological and infectious diseases (F = 12.417, P = 0.000). The serum 25-(OH)D₃ in neonates whose mothers had none or one perinatal complication were higher than those with two or more (F = 13.299, P = 0.000). The neonates with eosinophils ≤5% or normal platelet counts or serum Ca⁺⁺ ≥0.9 mmol/L have higher serum 25-(OH)D₃. Neonates born in winter were at risk for vitamin D insufficiency, and the incidence of infectious pneumonia, sepsis, cytomegalovirus infection, and hypocalcemia in the vitamin D insufficiency group were higher than sufficiency group (P < 0.05). The serum CD3+, CD3+CD4+, and IgA levels in vitamin D sufficiency neonates were significantly higher than those in insufficiency group (P < 0.05).

CONCLUSION

The prevalence of vitamin D insufficiency was 28.24%, and birth in winter was a risk factor for vitamin D insufficiency in hospitalized full-term neonates in Suzhou area. Neonates with infectious pneumonia, sepsis, cytomegalovirus infection, and hypocalcemia exhibited a high risk of vitamin D insufficiency. The serum CD3⁺, CD3⁺CD4⁺, and IgA levels in neonates with vitamin D insufficiency were lower.

COVID-19 and Vitamin D Misinformation on YouTube: Content Analysis

Background

The “infodemic” accompanying the SARS-CoV-2 virus pandemic has the potential to increase avoidable spread as well as engagement in risky health behaviors. Although social media platforms, such as YouTube, can be an inexpensive and effective method of sharing accurate health information, inaccurate and misleading information shared on YouTube can be dangerous for viewers. The confusing nature of data and claims surrounding the benefits of vitamin D, particularly in the prevention or cure of COVID-19, influences both viewers and the general “immune boosting” commercial interest.

Objective

The aim of this study was to ascertain how information on vitamin D and COVID-19 was presented on YouTube in 2020.

Methods

YouTube video results for the search terms “COVID,” “coronavirus,” and “vitamin D” were collected and analyzed for content themes and deemed useful or misleading based on the accuracy or inaccuracy of the content. Qualitative content analysis and simple statistical analysis were used to determine the prevalence and frequency of concerning content, such as confusing correlation with causation regarding vitamin D benefits.

Results

In total, 77 videos with a combined 10,225,763 views (at the time of data collection) were included in the analysis, with over three-quarters of them containing misleading content about COVID-19 and vitamin D. In addition, 45 (58%) of the 77 videos confused the relationship between vitamin D and COVID-19, with 46 (85%) of 54 videos stating that vitamin D has preventative or curative abilities. The major contributors to these videos were medical professionals with YouTube accounts. Vitamin D recommendations that do not align with the current literature were frequently suggested, including taking supplementation higher than the recommended safe dosage or seeking intentional solar UV radiation exposure.

Conclusions

The spread of misinformation is particularly alarming when spread by medical professionals, and existing data suggesting vitamin D has immune-boosting abilities can add to viewer confusion or mistrust in health information. Further, the suggestions made in the videos may increase the risks of other poor health outcomes, such as skin cancer from solar UV radiation.

Importance of Vitamin D3 in COVID-19 Patients

Outbreaks of a respiratory ailment in Wuhan, China, known as the Corona virus Disease-2019 (COVID-19), began in late December 2019. Since then, several pieces of advice have been made to boost the immune system to fight more efficiently with this infection. Previously published studies showed that vitamin D3 (Vit D3) level was low in COVID-19 patients. One of the most important factors in COVID-19 severity would be the inflammatory response. It is well documented that the inflammatory cytokine storm increases the severity of COVID-19. Cytokine storm results from dysregulation of the innate immune system with an outpouring of proinflammatory cytokines and chemokines, leading to abnormal activation of the adaptive immune pathway. It has been approved that Vit D3 has immunomodulatory functions and plays an anti-inflammatory role, particularly in viral infections. Therefore, the current study was designed to investigate the possible role of Vit D3 deficiency in the COVID-19 patients' innate immunity. This study included 180 participants who were divided into group (A) consisted of 60 COVID-19 positive patients with normal level of Vit D3, group (B) consisted of 60 COVID-19 positive patients with Vit D3 deficiency, and group (C) consisted of 60 COVID-19 positive patients that had received Vit D3 therapy. The results showed that the rate of hospitalization in the group (B) (41.3%) was significantly increased, compared to group (A) (12.5%). In this regard, Vit D3 therapy led to a significant increase in the level of Vit D3, and the patients who received Vit D3 were recovered from hospital 5 days on average sooner than those in the group (B). Therefore, the consumption of Vit D3 as a daily supplement would be a reasonable suggestion for these days of the COVID-19 pandemic to increase the power of immunity of the body.

The role of vitamin D in reducing SARS-CoV-2 infection: An update

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is having a disastrous impact on global health. Recently, several studies examined the potential of vitamin D to reduce the effects of SARS-CoV-2 infection by modulating the immune system. Indeed, vitamin D has been found to boost the innate immune system and stimulate the adaptive immune response against SARS-CoV-2 infection. In this review, we provide a comprehensive update of the immunological mechanisms underlying the positive effects of vitamin D in reducing SARS-CoV-2 infection as well as a thorough survey of the recent epidemiological studies and clinical trials that tested vitamin D as a potential therapeutic agent against COVID-19 infection. We believe that a better understanding of the histopathology and immunopathology of the disease as well as the mechanism of vitamin D effects on COVID-19 severity will ultimately pave the way for a more effective prevention and control of this global pandemic.

Vitamin D and cardiovascular health

The principal source of vitamin D in humans is its biosynthesis in the skin through a chemical reaction dependent on sun exposure. In lesser amounts, the vitamin can be obtained from the diet, mostly from fatty fish, fish liver oil and mushrooms. Individuals with vitamin D deficiency, defined as a serum level of 25 hydroxyvitamin D < 20 ng/dl, should be supplemented. Vitamin D deficiency is a prevalent global problem caused mainly by low exposure to sunlight. The main role of 1,25 dihydroxyvitamin D is the maintenance of calcium and phosphorus homeostasis. However, vitamin D receptors are found in most human cells and tissues, indicating many extra-skeletal effects of the vitamin, particularly in the immune and cardiovascular (CV) systems. Vitamin D regulates blood pressure by acting on endothelial cells and smooth muscle cells. Its deficiency has been associated with various CV risk factors and appears to be linked to a higher mortality and incidence of CV disease (CVD). Several mechanisms have been proposed relating vitamin D deficiency to CV risk factors such as renin-angiotensin-aldosterone system activation, abnormal nitric oxide regulation, oxidative stress or altered inflammatory pathways. However, in the latest randomized controlled trials no benefits of vitamin D supplementation for CVD have been confirmed. Although more work is needed to establish the protective role of vitamin D in this setting, according to current evidences vitamin D supplements should not be recommended for CVD prevention.

Serum vitamin D deficiency and risk of epithelial ovarian cancer in Lagos, Nigeria

The studies that have evaluated the association between vitamin D and risk of ovarian cancer have reported inconsistent findings. Many of these studies were carried out in regions with relatively low sunshine all year round unlike in Africa. This study was aimed to determine the relationship between vitamin D deficiency and epithelial ovarian cancer (EOC) amongst women in Lagos, Nigeria. We conducted a case–control study involving women with histologically confirmed EOC (case group) and an equal number of healthy women without cancer (control group) treated at the gynaecological oncology units of two public tertiary hospitals in Lagos, Nigeria, between 1 August, 2016 and 31 May, 2017. Relevant information was obtained from the participants using a structured interviewer-administered questionnaire, and then, venous blood samples were collected and analysed for serum 25-hydroxyvitamin D levels using the CALBIOTECH® 25(OH) vitamin D ELISA kit. The descriptive statistics were conducted for all relevant data, and the multivariable analysis using binary logistic regression model was performed to examine the association between vitamin D deficiency and EOC after adjusting for all possible confounders. The mean age of the participants was 50.6 ± 11.1 years. There was no statistically significant association between serum vitamin D deficiency and EOC (p = 0.09). However, 10 mmol/L change in circulating vitamin D levels was associated with EOC amongst the study participants (adjusted odds ratio 0.96; 95% confidence interval 0.93–0.99; p = 0.04), but following adjustment for potential confounders in a multivariable analysis, there was no statistically significant relationship observed with EOC (adjusted odds ratio 0.99; 95% confidence interval 0.97–1.00; p = 0.06). In addition, there was no evidence of an interaction effect between these confounders and change in circulating 25(OH)D levels in relation to the risk of EOC. The study revealed no statistically significant association between the circulating levels of vitamin D and the risk of EOC. A better assessment of sun exposure in the future as well as better dietary compositional data may help to clarify whether the association between vitamin D and EOC actually exists. Therefore, the future large prospective longitudinal studies are recommended to further examine this relationship and then evaluate the possible need for vitamin D supplementation in women with an increased risk of EOC in Nigeria.

Normal fertilisation rates and serum 25-OHD levels among couples undergoing in-vitro fertilisation: a prospective cohort study

Background

The aim of this study was to explore the correlation between serum vitamin D levels in couples undergoing in-vitro fertilisation (IVF) and normal fertilisation process.

Methods

Between March 2016 and March 2017, we performed a prospective cohort study at an academic reproductive medicine centre to measure serum 25-hydroxyvitaminD (25-OHD) levels of 1232 couples before controlled ovarian stimulation. Generalized linear regression and binary multivariate logistic regression were employed to assess whether 25-OHD levels in men and women correlated with normal fertilisation rates and low fertilisation rate (LFR).

Results

Serum 25-OHD levels in women were classified into three groups: Group A, less than 10%; Group B, between 10 and 90%; and Group C, greater than 90%. Using generalized linear regression, we observed that female 25-OHD levels were related to normal fertilisation rates. Adjusted normal fertilisation rates from Group A to Group C in women were 59.50, 62.72, and 66.13%, respectively (P = 0.007). After binary logistic regression analysis, for women, compared with Group C, the ORs for LFR were 4.814 in Group A (95% CI, 1.266–18.309, P = 0.021) and were 3.204 in Group B (95% CI, 0.949–10.812, P = 0.061). Male 25-OHD levels were not related to the probability of low fertilisation rate (P > 0.05).

Conclusions

Circulating 25-OHD concentrations in women appear to be associated with normal fertilisation rates and low fertilisation rates in IVF cycles, but not in men. A further randomized controlled trial with vitamin D supplementation is needed to demonstrate whether female vitamin D levels exert an effect on the normal fertilisation process.

Trial registration

https://clinicaltrials.gov/;NCT03305510; Registered 08 October 2017 - Retrospectively registered.

Five salmon dinners per week were not sufficient to prevent the reduction in serum vitamin D in autumn at 60° north latitude: a randomised trial

Low serum concentrations of several vitamins have been linked to increased risk of diseases including insulin resistance and type 2 diabetes (T2D). Fish is a good source of several vitamins, and the prevalence of T2D is low in populations with high fish intake. The aim of the present study was to investigate the effects of high fish intake on vitamins in serum from adults in autumn in South-Western Norway at 60° north latitude. In this randomised clinical trial, sixty-three healthy participants with overweight/obesity consumed 750 g/week of either cod (n22) or salmon (n22) as five weekly dinners or were instructed to continue their normal eating habits but avoid fish intake (Control group,n19) for 8 weeks. The estimated vitamin D intake was significantly increased in the Salmon group when compared with the Cod group (P= 6·3 × 10−4) and with the Control group (P= 3·5 × 10−6), with no differences between groups for estimated intake of vitamins A, B1, B2, B3, B6, B9, C and E. Serum 25-hydroxyvitamin D3concentration was decreased in all groups after 8 weeks; however, the reduction in the Salmon group was significantly smaller compared with the Cod group (P= 0·013) and the Control group (P= 0·0060). Cod and salmon intake did not affect serum concentrations of the other measured vitamins. The findings suggest that 750 g/week of salmon was not sufficient to prevent a decrease in serum 25-hydroxyvitamin D3in autumn in South-Western Norway in adults with overweight/obesity.

Estimation of exposure durations for vitamin D production and sunburn risk in Switzerland

Although overexposure to solar ultraviolet radiation (UVR) is responsible for cutaneous melanoma and epithelial skin cancer and can cause negative health effects such as sunburn, a "little and often" exposure regime is often suggested to produce naturally recommended vitamin D levels, being essential for skeletal health. This study aimed to quantify solar UV doses needed to trigger 1000 International Units (IU) vitamin D doses and, at the same time, producing sunburn in Switzerland. Solar UV erythema irradiance (in mW/m2) measured at four meteorological stations in Switzerland for the period 2005-2017 were used to evaluate effective solar UV radiation producing 1000 IU vitamin D doses in skin phototype II and III individuals. Daily solar UV exposure durations (in minutes) needed to produce vitamin D with limited sunburn risk were estimated while considering mean vitamin D food intake of the Swiss population and seasonal skin coverage. In summer and spring, with 22% of uncovered skin, 1000 IU vitamin D doses are synthesized in 10-15 min of sun exposure for adults. Exposure durations between erythema risk and 1000 IU vitamin D production vary between 9 and 46 min. In winter and autumn, the recommended vitamin D production without sunburn risks often unachievable, since up to 6.5 h of sun exposure might be necessary considering 8-10% of uncovered skin surface. The vitamin D food intake only represented 10% of the recommended vitamin D production and remained unchanged throughout the year. These findings might clarify why vitamin D deficiency is common in Switzerland. Moreover, exposure durations between recommended vitamin D and increased sunburn risk might only differ by few minutes. Without additional oral vitamin D supplementation, daily doses of vitamin D (1000 IU) are not reachable in autumn and winter months in Switzerland.

Compilation and spatio-temporal analysis of publicly available total solar and UV irradiance data in the contiguous United States

Skin cancer is the most common type of cancer in the United States, the majority of which is caused by overexposure to ultraviolet (UV) irradiance, which is one component of sunlight. National Environmental Public Health Tracking Program at CDC has collaborated with partners to develop and disseminate county-level daily UV irradiance (2005-2015) and total solar irradiance (1991-2012) data for the contiguous United States. UV irradiance dataset was derived from the Ozone Monitoring Instrument (OMI), and solar irradiance was extracted from National Solar Radiation Data Base (NSRDB) and SolarAnywhere data. Firstly, we produced daily population-weighted UV and solar irradiance datasets at the county level. Then the spatial distributions and long-term trends of UV irradiance, solar irradiance and the ratio of UV irradiance to solar irradiance were analyzed. The national average values across all years are 4300 Wh/m2, 2700 J/m2 and 130 mW/m2 for global horizontal irradiance (GHI), erythemally weighted daily dose of UV irradiance (EDD) and erythemally weighted UV irradiance at local solar noon time (EDR), respectively. Solar, UV irradiances and the ratio of UV to solar irradiance all increased toward the South and in some areas with high altitude, suggesting that using solar irradiance as indicator of UV irradiance in studies covering large geographic regions may bias the true pattern of UV exposure. National annual average daily solar and UV irradiances increased significantly over the years by about 0.3% and 0.5% per year, respectively. Both datasets are available to the public through CDC's Tracking network. The UV irradiance dataset is currently the only publicly-available, spatially-resolved, and long-term UV irradiance dataset covering the contiguous United States. These datasets help us understand the spatial distributions and temporal trends of solar and UV irradiances, and allow for improved characterization of UV and sunlight exposure in future studies.

Silica-based nanosystems for therapeutic applications in the skin

Aging, exposure to oxidants, infectious pathogens, inflammogens, ultraviolet radiation and other environmental and genetic factors can result in the development of various skin disorders. Despite immense progress being made in dermatological treatments, many skin-associated problems still remain difficult to treat and various therapies have limitations. Progress in silica-based nanomaterials research provides an opportunity to overcome these drawbacks and improve therapies and is a promising tool for inclusion in clinical practice to treat skin diseases. This review focuses on the use of various types of silica nanoparticles with therapeutic applications in various skin disorders. These nanosystems improve treatment efficacy by maintaining or enhancing the effect of several drugs and are useful tools for nanomedicine, pharmaceutical sciences and future clinical applications.

Vitamin D Deficiency: Effects on Oxidative Stress, Epigenetics, Gene Regulation, and Aging

Recent advances in vitamin D research indicate that this vitamin, a secosteroid hormone, has beneficial effects on several body systems other than the musculoskeletal system. Both 25 dihydroxy vitamin D [25(OH)₂D] and its active hormonal form, 1,25-dihydroxyvitamin D [1,25(OH)₂D] are essential for human physiological functions, including damping down inflammation and the excessive intracellular oxidative stresses. Vitamin D is one of the key controllers of systemic inflammation, oxidative stress and mitochondrial respiratory function, and thus, the aging process in humans. In turn, molecular and cellular actions form 1,25(OH)₂D slow down oxidative stress, cell and tissue damage, and the aging process. On the other hand, hypovitaminosis D impairs mitochondrial functions, and enhances oxidative stress and systemic inflammation. The interaction of 1,25(OH)₂D with its intracellular receptors modulates vitamin D–dependent gene transcription and activation of vitamin D-responsive elements, which triggers multiple second messenger systems. Thus, it is not surprising that hypovitaminosis D increases the incidence and severity of several age-related common diseases, such as metabolic disorders that are linked to oxidative stress. These include obesity, insulin resistance, type 2 diabetes, hypertension, pregnancy complications, memory disorders, osteoporosis, autoimmune diseases, certain cancers, and systemic inflammatory diseases. Vitamin D adequacy leads to less oxidative stress and improves mitochondrial and endocrine functions, reducing the risks of disorders, such as autoimmunity, infections, metabolic derangements, and impairment of DNA repair; all of this aids a healthy, graceful aging process. Vitamin D is also a potent anti-oxidant that facilitates balanced mitochondrial activities, preventing oxidative stress-related protein oxidation, lipid peroxidation, and DNA damage. New understandings of vitamin D-related advances in metabolomics, transcriptomics, epigenetics, in relation to its ability to control oxidative stress in conjunction with micronutrients, vitamins, and antioxidants, following normalization of serum 25(OH)D and tissue 1,25(OH)₂D concentrations, likely to promise cost-effective better clinical outcomes in humans.

Inverted U-shaped relationship between vitamin D and ever-reported eczema in US adults

BACKGROUND

Eczema is a skin condition which affects up to 10% to 20% of people worldwide. Previous literature finds that low vitamin D levels may be a risk factor for eczema, but the association is not clear.

METHODS

We used the cross-sectional data from U.S. National Health and Nutrition Examination Survey 2005-2006. Adults were defined as 20 years and older. The association between eczema and serum 25-hydroxyvitamin D [25(OH)D] was estimated using multivariate logistic regression models adjusted for patient demographics, lifestyle variables, stress, and medical comorbidities. Restricted cubic spline analyses were performed to explore nonlinear relationship. We also stratified by race.

RESULTS

A total of 3921 adults were included in the analysis. The prevalence of ever-report of eczema was 7.94% in US adults. Reports of eczema were higher in people with higher socioeconomic status, depressive symptoms, previous history of asthma and hay fever, female, sampled in summer, and nonHispanic white. The logistic regression found higher odds ratio of eczema in vitamin D deficiency group (<50 nmol/L) compared to sufficiency group (>75 nmol/L) (OR = 1.81, 95% CI: 1.09-3.01, P = 0.02). The spline analysis found an inverted U-shaped relationship between eczema and serum 25(OH)D level. Eczema risk reached the highest at around 45 nmol/L, with decreasing risk in both directions away from this value. This relationship was absent in nonHispanic black population.

CONCLUSION

Vitamin D is associated with reports of eczema in nonHispanic white population, but not in the nonHispanic black population in the United States.

Vitamin D history part III: the "modern times"-new questions for orthopaedic practice: deficiency, cell therapy, osteomalacia, fractures, supplementation, infections

PURPOSE

The nutritional basis for rickets was described between 1880 and 1915, at the same period of discovery of other "vital substances" or vitamins. In contrast, rickets could also be prevented or cured by sunshine. But as the capacity to produce vitamin D depends on exposure to ultraviolet B rays (UVB) from sunlight or artificial sources, vitamin D became one of the most frequently used "drugs" in the twentieth century to compensate for insufficient exposure to UVB of humans. Furthermore, as the understanding of vitamin D metabolism grew during the twentieth century, other concerns than rickets occurred for the orthopaedic surgeon: In recent history, deficiency is explored as being an associated factor of different bone pathologies as fracture or prosthetic infection. The aim of this review is to analyze these new data on vitamin D.

MATERIALS AND METHODS

During the twentieth century, there were many concerns for the orthopaedic surgeon: sources and synthesis of vitamin D, regulation of the calcium deposition process for both children and adults, when vitamin D deficiency is observed, and what the best method of vitamin D supplementation is. As target genes regulated by vitamin D are not limited to those involved in mineral homeostasis, orthopedists recently discovered that vitamin D might prevent periprosthetic infection.

RESULTS

The primary source (80%) of vitamin D is dermal synthesis related to the sun. Dietary sources (20%) of vitamin D are fat fishe, beef, liver, and eggs. Vitamin D is produced industrially to be used in fortified foods and supplements. Maintenance of skeletal calcium balance is mediated through vitamin D receptors. Progenitor cells, chondrocytes, osteoblasts, and osteoclasts contain these receptors which explains the role of vitamin D in cell therapy, in the prevention of rickets and osteomalacia. Despite fortified foods, the prevalence of deficiency remains endemic in north latitudes. However, the definition of vitamin D insufficiency or deficiency remains controversial. Vitamin D has been evaluated in patients undergoing fractures and elective orthopaedic procedures Although supplementation may not be able to prevent or cure all the orthopaedic pathologies, oral supplementation is able to improve the vitamin D levels of deficient patients. These vitamin D level improvements might be associated with better functional and clinical outcomes after some surgical procedures and improvement of immunity to decrease the risk of infection in arthroplasties.

CONCLUSION

Vitamin D deficiency is frequent and concerns millions of people in the world. It is therefore normal to find hypovitaminosis in various orthopaedic populations including trauma and arthroplasties. However, we do not know exactly if this phenomenon only reflects the general prevalence of vitamin D deficiency or has an influence on the outcome of some pathologies on specific populations at risk. After the success of treatment of rickets, it is disappointing that we are still wondering in the twenty-first century whether supplementation of a substance synthetized millions of years ago by plankton and necessary for growth of all the animals may improve (or not) clinical and functional outcomes of a simple fracture in humans.

Designing Safe General LED Lighting that Provides the UVB Benefits of Sunlight

The ultraviolet (UV) rays emitted from sunlight greatly influence human health. Excessive exposure to UV rays can be harmful to eyes and skin; however, limited UVB exposure is essential for the synthesis of vitamin D. Nowadays, owing to insufficient exposure to natural light, there is increasing concerns about low vitamin D amongst individuals. To address this issue, many lighting devices that provide UVB doses have been released; however, such devices are only used for treatments or for special purposes. This study proposes a general indoor lighting system with a UVB LED light source to provide safe UVB doses to users who spend large amounts of time indoors. The optical characteristics of two UVB LEDs with output of 20 and 100 mW were analyzed based on their distances and applied currents. The light source combination of UVB LEDS that meets the UV hazard standard of IEC-62471 was derived; this is a photobiological safety evaluation standard of LED lighting devices. We then produced a lighting module in which the UVB LED light source was applied to general LED lighting and measured and analyzed the spectral irradiance of the proposed lighting according to the measurement standard for the general lighting of IEC 62471. The actinic UV hazard (AUV) and near-UV hazard (NUV) were calculated to be 0.001 and 10 W/m2, respectively. Thus, the provision of UVB dose did not pose any risks. In addition, the total EUV (Erythemal weighted UV) dose when the proposed lighting was implemented for 16 h was 187.66 J/m2, confirming that this dose did not cause erythema for the general skin types (Skin Types 1–6). Further, the design plan of general indoor lighting with a UVB LED light source is presented.

p62 functions as an oncogene in colorectal cancer through inhibiting apoptosis and promoting cell proliferation by interacting with the vitamin D receptor

Objectives

The role of p62 in cancer is controversial. Evidence has shown that p62 is upregulated in different cancers and promotes tumour growth, such as in liver cancer and lung cancer. However, a recent study showed that the downregulation of p62 in hepatic stellate cells (HSCs) promotes hepatocellular carcinoma (HCC) development. How p62 is regulated in colorectal cancer (CRC) remains largely unknown. In this study, we aimed to investigate the roles and molecular mechanisms of p62 in CRC.

Materials and Methods

The expression levels of p62 in CRC tissues and adjacent non‐tumour tissues were determined by immunohistochemistry (IHC). Stable p62‐overexpression HCT116 cells and p62‐knockdown SW480 cells were established with lentiviral vectors. The role of p62 in CRC was investigated in in vitro and in vivo functional studies. The relationship between p62 and the vitamin D receptor (VDR) was investigated by coimmunoprecipitation (Co‐IP) assays.

Results

p62 was significantly upregulated in CRC, and a high p62 level was an independent risk factor for a poor prognosis in CRC patients. p62 promoted CRC migration and invasion by inhibiting apoptosis and promoting cell proliferation in vitro, and p62 aggravated tumour growth and metastasis in vivo. Co‐IP assays indicated that p62 interacts with the VDR and may target the NRF2‐NQO1 axis.

Conclusions

Our study suggested that p62 functions as an oncogene in CRC through inhibiting apoptosis and promoting cell proliferation by interacting with the VDR.

Effect of high dose vitamin D3 therapy on serum vitamin D3 levels in vitamin D insufficient adults with cystic fibrosis

BACKGROUND

The effect of a high dose oral cholecalciferol repletion strategy in Vitamin D insufficient adults with CF is still unknown. Therefore, we assessed the effectiveness of our current approach, giving oral vitamin D3 supplementation at a dose of 10,000 IU from Monday to Friday for a total of 50,000 IU D3 weekly in vitamin D insufficient adult with CF.

METHODS

We performed a retrospective chart review of all 59 adult CF patients between the ages of 17 and 64 years routinely followed at the CF Adult Program of Winnipeg Health Sciences Centre. Through consultation with the endocrinologist, our clinic vitamin D repletion protocol for treating CF adult patients who have serum 25-hydroxyvitamin D (25-OHD) < 30 ng/ml (<75 nmol/L) was to prescribe vitamin D3 10,000 IU orally from Monday to Friday (or the weekly equivalent of 50,000 IU) for 12 weeks in addition to their regular CF vitamin that supplied from 800 to 2000 IU vitamin D3 daily. Cholecalciferol was conveniently administered orally as either one capsule (oil-based) 10,000 IU or one tablet (powder-based) 10,000 IU. All patients were instructed to obtain follow-up serum 25-OHD levels post completion of treatment.

RESULTS

Of the 59 adult patients at our CF Clinic, 35 patients (59%) had below optimal serum 25-OHD levels. Of the 35 patients identified, 10 patients with insufficient serum 25-OHD levels between 10 and 30 ng/ml (25-75 nmol/L) fulfilled the inclusion criteria. A significant increase in serum 25-OHD levels was observed (P < 0.01) from mean value of 21.6 ± 5.9 ng/ml (54.1 ± 14.8 nmol/L) at baseline to 31.7 ± 9.1 ng/ml (79.3 ± 22.8 nmol/L) ≥ 2 months post intervention. The current treatment approach was successful in treating Vitamin D insufficiency in 70% of the patients with low 25-OHD levels.

CONCLUSION

The results of this study demonstrate that a large number of adults attending Winnipeg Health Sciences Centre CF Clinic have serum 25-OHD levels below 30 ng/ml (75 nmol/L). This supports the need for dedicated and individualized approach to manage this condition. High dose therapy of vitamin D3, although a more aggressive treatment approach, may result in achieving optimal levels of serum 25-OHD in adults with CF.

Cytotoxicity and apoptotic cell death induced by Vitis vinifera peel and seed extracts in A431 skin cancer cells

Vitis vinifera. L is one of the most widely consumed fruits in the world and are rich in antioxidant abundant polyphenols. The present study was carried out to assess the antiproliferative and apoptotic effects of Vitis vinifera peel and seed extracts in an in vitro model using human epidermoid carcinoma A431 cell lines. Vitis vinifera peel and seed extracts were incubated with A431 cells to evaluate the antiproliferative, apoptotic effects and the morphological apoptotic changes induced by the extracts. Mitochondrial membrane potential was also measured after incubating the cells with extracts. At the inhibitory concentration (IC₅₀), grape seed extract (111.11 µg/mL) and grape peel extract (319.14 µg/mL) were incubated for 24 h with A431 cells. Vitis vinifera peel and seed extracts were able to impart cytotoxic effects, induced apoptosis and apoptotic morphological changes in A431 cells significantly (p < 0.01) and this effect is associated with the interference with mitochondrial membrane potential. This reduction in mitochondrial membrane potential probably initiated the apoptotic cascade in the extracts treated cells. Vitis vinifera peel and seed phytochemicals can selectively target cancer cells and the phytochemicals that are occluded can serve as potential anticancer agents providing better efficacy in killing cancer cells.

Pterygia are indicators of an increased risk of developing cutaneous melanomas

AIM

To investigate whether pterygium is an indicator of an increased risk of cutaneous melanoma (CM).

METHODS

A matched-cohort study, using linked health administrative data sets to identify all hospital-treated pterygium in Western Australia (WA) between 1979 and 2014. We identified pterygium cases from hospital diagnosis and/or procedure International Classification of Diseases 9th revision (ICD-9) and 10th revision (ICD-10) codes and matched cases by age, sex and residential postcode to WA Electoral Roll controls with no known history of pterygium. Both cohorts were linked to the WA Cancer Registry and the WA Deaths Registry.

RESULTS

23 625 people had pterygium treatment (64% male) in WA hospitals. The median age for pterygium diagnosis and/or treatment was 49 years (range 14-96). There were significantly more CM cases in the pterygium cohort compared with the control cohort (1083 vs 874; p<0.001). In a logistic regression analysis, there was a 24% increase in the odds of developing a CM in the pterygium cohort, compared with controls, after controlling for other predictors (OR 1.24, 95% CI 1.1 to 1.4). The incident rate ratio (IRR) of a malignant CM diagnosis was 20% greater in people who had treatment for a pterygium compared with controls (IRR 1.2, 95% CI 1.0 to 1.4).

CONCLUSION

The presence of a pterygium indicates a significantly increased risk of developing a CM. Eye care providers who see patients with developing pterygia should advise these patients of this increased risk and recommend regular skin surveillance.

Hypovitaminosis D in patients undergoing kidney transplant: the importance of sunlight exposure

OBJECTIVES:

Recent studies have shown a high prevalence of hypovitaminosis D, defined as a serum 25-hydroxyvitamin D level less than 30 ng/ml, in both healthy populations and patients with chronic kidney disease. Patients undergoing kidney transplant are at an increased risk of skin cancer and are advised to avoid sunlight exposure. Therefore, these patients might share two major risk factors for hypovitaminosis D: chronic kidney disease and low sunlight exposure. This paper describes the prevalence and clinical characteristics of hypovitaminosis D among patients undergoing kidney transplant.

METHODS:

We evaluated 25-hydroxyvitamin D serum levels in a representative sample of patients undergoing kidney transplant. We sought to determine the prevalence of hypovitaminosis D, compare these patients with a control group, and identify factors associated with hypovitaminosis D (e.g., sunlight exposure and dietary habits).

RESULTS:

Hypovitaminosis D was found in 79% of patients undergoing kidney transplant, and the major associated factor was low sunlight exposure. These patients had higher creatinine and intact parathyroid hormone serum levels, with 25-hydroxyvitamin D being inversely correlated with intact parathyroid hormone serum levels. Compared with the control group, patients undergoing kidney transplant presented a higher prevalence of 25-hydroxyvitamin D deficiency and lower serum calcium, phosphate and albumin but higher creatinine and intact parathyroid hormone levels.

CONCLUSIONS:

Our results confirmed the high prevalence of hypovitaminosis D in patients undergoing kidney transplant. Therapeutic strategies such as moderate sunlight exposure and vitamin D supplementation should be seriously considered for this population.

The relationship between serum vitamin D levels and sleep quality in fixed day indoor field workers in the electronics manufacturing industry in Korea

Background

Although recent studies have investigated the influence of vitamin D on sleep patterns, there is a lack of research on the relationship between vitamin D and sleep patterns in Korean workers. This study focused on the relationship between serum vitamin D levels and sleep in fixed day indoor field workers in the electronics manufacturing industry in Korea.

Methods

The 1472 subjects who were included in this study were selected from fixed day workers in the electronics manufacturing industry who had received a worker’s special health examination at a hospital in Changwon, South Gyeongsang Province between January 2015 and December 2015. Nighttime workers and those who showed symptoms of depression were excluded from this study. The sociodemographic and lifestyle variables of the participants were investigated, including age, sex, marital status, level of education, body mass index, smoking habits, alcohol consumption habits, and regular exercise. Work-related factors were evaluated, such as employee tenure and occupational stress. Serum 25-hydroxyvitamin D was measured as an indicator of vitamin D levels, and quality of sleep was evaluated using the Pittsburgh Sleep Quality Index (PSQI) translated into Korean.

Results

The subjects had a mean serum vitamin D level of 13.70 ± 5.93 ng/mL. Vitamin D deficiency, defined as a serum vitamin D level of <10 ng/mL, was found in 24.8% of males and significantly more frequently in females (47.6%). Poor sleep quality was reported by 19.8% of participants with serum vitamin D levels ≥10 ng/mL and by 21.7% of those with serum vitamin D levels <10 ng/mL, which was a significant difference (P = .007). Multiple logistic regression analysis adjusting for significant variables found that poor sleep quality was more likely in those with vitamin D deficiency than those with higher serum vitamin D levels (odds ratio = 1.36; 95% CI, 1.01–1.82). A comparison of serum vitamin D levels and PSQI components showed that the mean scores for subjective sleep quality, sleep latency, and sleep duration were significantly higher in the vitamin D-deficient participants, indicating that the vitamin D-deficient participants had poorer sleep quality.

Conclusions

This study investigated serum vitamin D levels in fixed day indoor field workers in the manufacturing industry in Korea and analyzed the relationship of vitamin D deficiency with sleep quality. A significant correlation was found between serum vitamin D deficiency and poor sleep quality. Based on the results of this study, sleep disorder management for workers can be improved by providing regular examinations checking their serum vitamin D levels and supplying vitamin D to workers with serum vitamin D deficiency to enhance their quality of sleep.

The vitamin D deficiency pandemic: Approaches for diagnosis, treatment and prevention

Vitamin D deficiency and insufficiency is a global health issue that afflicts more than one billion children and adults worldwide. The consequences of vitamin D deficiency cannot be under estimated. There has been an association of vitamin D deficiency with a myriad of acute and chronic illnesses including preeclampsia, childhood dental caries, periodontitis, autoimmune disorders, infectious diseases, cardiovascular disease, deadly cancers, type 2 diabetes and neurological disorders. This review is to put into perspective the controversy surrounding the definition for vitamin D deficiency and insufficiency as well as providing guidance for how to treat and prevent vitamin D deficiency.

Vitis vinifera peel and seed gold nanoparticles exhibit chemopreventive potential, antioxidant activity and induce apoptosis through mutant p53, Bcl-2 and pan cytokeratin down-regulation in experimental animals

Several studies suggest surface modifications of gold nanoparticles (AuNPs) by capping agents or surface coatings could play an important role in biological systems, and site directed delivery. The present study was carried out to assess the antioxidant and apoptotic activities of the Vitis vinifera peel and seed gold nanoparticles in experimentally induced cancer in Swiss albino mice. 12-dimethylbenz [a] anthracene (DMBA) (single application) and 12-O-tetradecanoylphorbol 13-acetate (TPA) (thrice a week) were applied on the dorsal area of the skin to induce skin papillomagenesis in Swiss albino mice for 16 weeks. Gold nanoparticles were synthesized using Vitis vinifera peel and seed aqueous extracts and characterized by Transmission electron microscopic (TEM) analyses. On topical application, peel and seed gold nanoparticles demonstrated chemopreventive potential by significantly (p<0.05) reducing the cumulative number of tumors while increasing the antioxidant enzyme activities in the gold nanoparticles treated mice. The down-regulated expression of mutant p53, Bcl-2 and the levels of pan-cytokeratins might have facilitated the process of apoptosis in the chemical carcinogenesis process. The results were supported by the histopathological evaluation which exhibited mild dysplasia and acanthosis in the skin tissues of Vitis vinifera peel and seed AuNPs treated mice. Based on the present study, the chemopreventive action of Vitis vinifera peel and seed AuNPs is probably due to its ability to stimulate the antioxidant enzymes within the cells and suppressed abnormal skin cell proliferation that occurred during DMBA-induced skin papillomagenesis.

Vitamin D Levels in Children with Adenotonsillar Hypertrophy and Otitis Media with Effusion

INTRODUCTION

Vitamin D has been suggested to play a considerable role in the function of the immune system in various infectious, inflammatory, and autoimmune conditions. Otitis media with effusion (OME), defined as the presence of non-purulent fluid within the middle ear without signs or symptoms of suppurative otitis media, has a number of inflammatory predisposing factors. This study was designed to explore the association between vitamin D deficiency and OME.

MATERIALS AND METHODS

In this cross-sectional study, 74 children aged 2-7 years with an obstructive indication for adenotonsillectomy were included. Patients were divided into two groups based on the need for ventilation tube insertion for OME. Thirty-two children were enrolled in the OME group and 42 in the control group. The mean vitamin D level was compared between the two groups.

RESULTS

Mean vitamin D concentration in all patients was 11.96±5.85 ng/ml (9.79±4.36 ng/ml in the OME group and 13.61±6.33 ng/ml in the control group; P=0.003). There was also a significant difference in levels of vitamin D in patients referred in winter (9.0±2.94 ng/ml) compared with the summer (19.85±4.21 ng/ml; P=0.001). Data analyzed based on the season in which the patients were referred showed no significant difference between the OME and the control group.

CONCLUSION

Although our results showed lower serum levels of vitamin D in OME patients, the difference was not significant when seasons were taken into consideration. Therefore, the season is an important confounding factor in any research related to vitamin D due to the effect of sun-induced vitamin D.

Concurrent beneficial (vitamin D production) and hazardous (cutaneous DNA damage) impact of repeated low-level summer sunlight exposures

Background

The concurrent impact of repeated low‐level summer sunlight exposures on vitamin D production and cutaneous DNA damage, potentially leading to mutagenesis and skin cancer, is unknown.

Objectives

This is an experimental study (i) to determine the dual impact of repeated low‐level sunlight exposures on vitamin D status and DNA damage/repair (via both skin and urinary biomarkers) in light‐skinned adults; and (ii) to compare outcomes following the same exposures in brown‐skinned adults.

Methods

Ten white (phototype II) and six South Asian volunteers (phototype V), aged 23–59 years, received 6 weeks’ simulated summer sunlight exposures (95% ultraviolet A/5% ultraviolet B, 1·3 standard erythemal doses three times weekly) wearing summer clothing exposing ~35% body surface area. Assessments made were circulating 25‐hydroxyvitamin D [25(OH)D], immunohistochemistry for cyclobutane pyrimidine dimer (CPD)‐positive nuclei and urinary biomarkers of direct and oxidative (8‐oxo‐deoxyguanosine) DNA damage.

Results

Serum 25(OH)D rose from mean 36·5 ± 13·0 to 54·3 ± 10·5 nmol L⁻¹ (14·6 ± 5·2 to 21·7 ± 4·2 ng mL⁻¹) in phototype II vs. 17·2 ± 6·3 to 25·5 ± 9·5 nmol L⁻¹ (6·9 ± 2·5 to 10·2 ± 3·8 ng mL⁻¹) in phototype V (P < 0·05). Phototype II skin showed CPD‐positive nuclei immediately postcourse, mean 44% (range 27–84) cleared after 24 h, contrasting with minimal DNA damage and full clearance in phototype V (P < 0·001). The findings did not differ from those following single ultraviolet radiation (UVR) exposure. Urinary CPDs remained below the detection threshold in both groups; 8‐oxo‐deoxyguanosine was higher in phototype II than V (P = 0·002), but was unaffected by UVR.

Conclusions

Low‐dose summer sunlight exposures confer vitamin D sufficiency in light‐skinned people concurrently with low‐level, nonaccumulating DNA damage. The same exposures produce minimal DNA damage but less vitamin D in brown‐skinned people. This informs tailoring of sun‐exposure policies.

What's already known about this topic?

Repeated low‐level exposures to simulated U.K. sunlight can produce vitamin D sufficiency in light‐skinned people, but the concurrent impact on cutaneous DNA damage is unknown.

What does this study add?

Low‐level simulated sunlight exposures in people of skin phototype II conferred vitamin D sufficiency concurrently with DNA damage, which showed partial clearance at 24 h and no evidence of accumulated damage after 6 weeks of exposures.

The same exposures produced minimal DNA damage but less vitamin D in brown‐skinned people (phototype V).

The findings are informative for sun‐exposure guidance.

Plain language summary available online

Vitamin D production in UK Caucasian and South Asian women following UVR exposure

BACKGROUND

It is known that skin pigmentation reduces the penetration of ultraviolet radiation (UVR) and thus photosynthesis of 25-hydroxvitamin D (25(OH)D). However ethnic differences in 25(OH)D production remain to be elucidated.

OBJECTIVE

The aim of this study was to investigate differences in vitamin D production between UK South Asian and Caucasian postmenopausal women, in response to a defined and controlled exposure to UVR.

DESIGN

Seventeen women; 9 white Caucasian (skin phototype II and III), 8 South Asian women (skin phototype IV and V) participated in the study, acting as their own controls. Three blood samples were taken for the measurement of vitamin D status during the run in period (9days, no sunbed exposure) after which, all subjects underwent an identical UVR exposure protocol irrespective of skin colour (9 days, 3 sun bed sessions, 6, 8 and 8min respectively with approximately 80% body surface exposed). Skin tone was measured four times during the study.

RESULTS

Despite consistently lower 25(OH)D levels in South Asian women, they were shown to synthesise vitamin D as efficiently as Caucasians when exposed to the same dose of UVR. Interestingly, the baseline level of vitamin D rather than ethnicity and skin tone influenced the amount of vitamin D synthesised.

CONCLUSIONS

This study have found no ethnic differences in the synthesis of 25(OH)D, possibly due to the baseline differences in 25(OH)D concentration or due to the small population size used in this study. Applying mixed linear model, findings indicated no effect of ethnicity and skin tone on the production of vitamin D; baseline level and length of exposure were the critical factors. To confirm that ethnicity and skin tone has no effect on 25(OH)D production, a larger sample size study is required that considers other ethnic groups with highly pigmented skin. Initial vitamin D status influences the amount of UVB needed to reach equal serum concentrations.

Local Adaptation of Sun-Exposure-Dependent Gene Expression Regulation in Human Skin

Sun-exposure is a key environmental variable in the study of human evolution. Several skin-pigmentation genes serve as classical examples of positive selection, suggesting that sun-exposure has significantly shaped worldwide genomic variation. Here we investigate the interaction between genetic variation and sun-exposure, and how this impacts gene expression regulation. Using RNA-Seq data from 607 human skin samples, we identified thousands of transcripts that are differentially expressed between sun-exposed skin and non-sun-exposed skin. We then tested whether genetic variants may influence each individual’s gene expression response to sun-exposure. Our analysis revealed 10 sun-exposure-dependent gene expression quantitative trait loci (se-eQTLs), including genes involved in skin pigmentation (SLC45A2) and epidermal differentiation (RASSF9). The allele frequencies of the RASSF9 se-eQTL across diverse populations correlate with the magnitude of solar radiation experienced by these populations, suggesting local adaptation to varying levels of sunlight. These results provide the first examples of sun-exposure-dependent regulatory variation and suggest that this variation has contributed to recent human adaptation.

Varying levels of sun-exposure across the world have significantly shaped human evolution. Previous analyses have found several skin pigmentation genes with evidence of strong evolutionary pressures throughout human history, manifesting as large differences in the frequency of genomic variants across populations. But even within populations, individuals respond differently to sun-exposure, suggesting variation in addition to the major differences in skin pigmentation across populations. Here we investigated whether genetic variants associate with response to sun-exposure within Europeans. To measure the response we analyzed gene expression in sun-exposed and non-sun-exposed skin, and identified ten genetic variants that associated with the sun-exposure response of nearby genes. One of these genetic variants, which associated with the sun-exposure response of the gene RASSF9, showed evidence of adaptation in humans in response to solar radiation. Together this evidence suggests that the regulation of gene expression is influenced by sun-exposure and that the sun-exposure dependent effect on RASSF9 expression may have had an effect on human fitness. To our knowledge, this is the first example of an environment-dependent regulatory variant with evidence of adaptation in humans.

Nucleotide Excision Repair and Vitamin D--Relevance for Skin Cancer Therapy

Ultraviolet (UV) radiation is involved in almost all skin cancer cases, but on the other hand, it stimulates the production of pre-vitamin D3, whose active metabolite, 1,25-dihydroxyvitamin D3 (1,25VD3), plays important physiological functions on binding with its receptor (vitamin D receptor, VDR). UV-induced DNA damages in the form of cyclobutane pyrimidine dimers or (6-4)-pyrimidine-pyrimidone photoproducts are frequently found in skin cancer and its precursors. Therefore, removing these lesions is essential for the prevention of skin cancer. As UV-induced DNA damages are repaired by nucleotide excision repair (NER), the interaction of 1,25VD3 with NER components can be important for skin cancer transformation. Several studies show that 1,25VD3 protects DNA against damage induced by UV, but the exact mechanism of this protection is not completely clear. 1,25VD3 was also shown to affect cell cycle regulation and apoptosis in several signaling pathways, so it can be considered as a potential modulator of the cellular DNA damage response, which is crucial for mutagenesis and cancer transformation. 1,25VD3 was shown to affect DNA repair and potentially NER through decreasing nitrosylation of DNA repair enzymes by NO overproduction by UV, but other mechanisms of the interaction between 1,25VD3 and NER machinery also are suggested. Therefore, the array of NER gene functioning could be analyzed and an appropriate amount of 1.25VD3 could be recommended to decrease UV-induced DNA damage important for skin cancer transformation.

Low serum vitamin D is associated with axial length and risk of myopia in young children

The aim of the study was to investigate the relationship between serum 25(OH)D levels and axial length (AL) and myopia in 6-year-old children. A total of 2666 children aged 6 years participating in the birth-cohort study Generation R underwent a stepwise eye examination. First, presenting visual acuity (VA) and AL were performed. Second, automated cycloplegic refraction was measured if LogMAR VA > 0.1. Serum 25-hydroxyvitamin D [25(OH)D] was determined from blood using liquid chromatography/tandem mass spectrometry. Vitamin D related SNPs were determined with a SNP array; outdoor exposure was assessed by questionnaire. The relationships between 25(OH)D and AL or myopia were investigated using linear and logistic regression analysis. Average 25(OH)D concentration was 68.8 nmol/L (SD ± 27.5; range 4–211); average AL 22.35 mm (SD ± 0.7; range 19.2–25.3); and prevalence of myopia 2.3 % (n = 62). After adjustment for covariates, 25(OH)D concentration (per 25 nmol/L) was inversely associated with AL (β −0.043; P < 0.01), and after additional adjusting for time spent outdoors (β −0.038; P < 0.01). Associations were not different between European and non-European children (β −0.037 and β −0.039 respectively). Risk of myopia (per 25 nmol/L) was OR 0.65 (95 % CI 0.46–0.92). None of the 25(OH)D related SNPs showed an association with AL or myopia. Lower 25(OH)D concentration in serum was associated with longer AL and a higher risk of myopia in these young children. This effect appeared independent of outdoor exposure and may suggest a more direct role for 25(OH)D in myopia pathogenesis.

The risks and benefits of sun exposure 2016

Public health authorities in the United States are recommending that men, women and children reduce their exposure to sunlight, based on concerns that this exposure will promote skin cancer. On the other hand, data show that increasing numbers of Americans suffer from vitamin D deficiencies and serious health problems caused by insufficient sun exposure. The body of science concerning the benefits of moderate sun exposure is growing rapidly, and is causing a different perception of sun/UV as it relates to human health. Melanoma and its relationship to sun exposure and sunburn is not adequately addressed in most of the scientific literature. Reports of favorable health outcomes related to adequate serum 25(OH)D concentration or vitamin D supplementation have been inappropriately merged, so that benefits of sun exposure other than production of vitamin D are not adequately described. This review of recent studies and their analyses consider the risks and benefits of sun exposure which indicate that insufficient sun exposure is an emerging public health problem. This review considers the studies that have shown a wide range health benefits from sun/UV exposure. These benefits include among others various types of cancer, cardiovascular disease, Alzheimer disease/dementia, myopia and macular degeneration, diabetes and multiple sclerosis. The message of sun avoidance must be changed to acceptance of non-burning sun exposure sufficient to achieve serum 25(OH)D concentration of 30 ng/mL or higher in the sunny season and the general benefits of UV exposure beyond those of vitamin D.

The angular distributions of ultraviolet spectral irradiance at different solar elevation angles under clear sky conditions

To investigate the angular distributions of UVA, UVB, and effective UV for erythema and vitamin D (vitD) synthesis, the UV spectral irradiances were measured at ten inclined angles (from 0° to 90°) and seven azimuths (from 0° to 180°) at solar elevation angle (SEA) that ranged from 18.8° to 80° in Shanghai (31.22° N, 121.55° E) under clear sky and the albedo of ground was 0.1. The results demonstrated that in the mean azimuths and with the back to the sun, the UVA, UVB, and erythemally and vitD-weighted irradiances increased with the inclined angles and an increase in SEA. When facing toward the sun at 0°-60° inclined angles, the UVA first increased and then decreased with an increase in SEA; at other inclined angles, the UVA increased with SEA. At 0°-40° inclined angles, the UVB and erythemally and vitD-weighted irradiances first increased and then decreased with an increase in SEA, and their maximums were achieved at SEA 68.7°; at other inclined angles, the above three irradiances increased with an increase in SEA. The maximum UVA, UVB, and erythemally and vitD-weighted irradiances were achieved at an 80° inclined angle at SEA 80° (the highest in our measurements); the cumulative exposure of the half day achieved the maximum at a 60° inclined angle, but not on the horizontal. This study provides support for the assessment of human skin sun exposure.