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

Erythemal UV radiation across Nigeria: where do we stand?

The deleterious effects of solar ultraviolet (UV) radiation on humans are of public health concern which demands constant global monitoring and intervention. This study analysed the latitudinal variations in mean daily and multi-year erythemal ultraviolet radiation (EUVR) across 7 states in Nigeria using satellite data from the Total Ozone Mapping Spectrophotometer (TOMS) and Ozone Mapping Instrument (OMI). The latitudes studied were 13° N, 8° N, 6° N and 4° N respectively, using 37 years of data obtained from phases: 1979–1988, 1989–1998, 1999–2008 and 2009–2020. The data obtained were statistically analysed using Ms Excel and MATLAB. The results of this study show that the mean daily EUVR at the selected latitudes ranges from 32.97 to 390 (mW/m²). The results show that Borno State located at latitude 13° N had the highest EUVR, while Rivers State recorded the least EUVR at latitude 4° N. Comparative analysis of all the locations studied indicates latitudinal and longitudinal variations because the eastern axis recorded higher values than its western counterpart on the same latitude. Box and whisker plots in this study summarized the latitudinal variance in the mean multi-year EUVR in each phase. Box and whisker plots from 2009–2020 showed that there was a drastic reduction in mean multi-year EUVR in this phase unlike in the other phases. The findings of this study when compared to the UV index show that the 37 years mean EUVR obtained across Nigeria ranged from 8–10 which is on the “very high” category. This study recommends the implementation of WHO suggestions in preventing the biological effects of solar UV radiation. Furthermore, the Nigerian government should curb ignorance among its citizens by heightening public awareness of the effects of EUVR.

Wearable ultraviolet radiation sensors for research and personal use

Skin cancers are strongly linked to personal exposure to ultraviolet (UV) radiation, yet UV exposure is also the most preventable risk factor. People are exposed to UV rays when they engage in outdoor activities, particularly exercise, which is an important health behavior. Thus, researchers and the general public have shown increasing interest in measuring UV exposure using wearable sensors during outdoor physical activity. However, minimal research exists at the intersection of UV sensors, personal exposure, adaptive behavior due to exposures, and risk of skin damage. Recent years have seen an influx of new consumer-based and research-based UV-sensing technologies with wide-ranging form factors and purposes to fill this research gap, yet a thorough review of available sensors for specific purposes does not exist. Hence, the overall goal of this state-of-the-art review is to synthesize the current academic and gray literature surrounding personal UV-sensing technologies. Peer-reviewed journal articles and "gray literature," such as working papers, manuals, and UV sensor websites, were reviewed, assessing attributes of UV wearables marketed for research use, personal use, or both. Overall, 13 wearable UV sensors are available for personal use and/or research applications. These sensors vary from electronic to photochromic, with large differences in price, data outputs, accuracy, and precision. Recommendations are provided for which sensors are most suitable for various types of research or public use. Notably, the review findings will help guide researchers in future studies assessing UV exposure during physical activity.

Assessment of sunlight exposure across industries and occupations using blood vitamin D as a biomarker

Objective

Exposure to ultraviolet (UV) radiation from sunlight induces the production of essential vitamin D, whereas overexposure to sunlight leads to skin cancer. Sunlight exposure has been measured using questionnaires, dosimeters, and vitamin D levels. Several studies have measured vitamin D in the working population; however, these studies were limited to certain occupations such as farmers and construction workers. In the present study, we evaluated sunlight exposure using blood vitamin D as an exposure surrogate across industries and occupations.

Methods

The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide study representing the Korean population. We analyzed data from KNHANES between 2008 and 2009. We examined the association between vitamin D levels and pertinent personal, seasonal, residential, and occupational factors. Furthermore, we developed a multiple regression model with factors other than occupational factors (industry and occupation) and obtained residual values. We computed the third quartile (Q3) of the residuals and then calculated the fractions exceeding the Q3 level for each combination of industry and occupation.

Results

Age, sex, body mass index, year, season, latitude, living area, living in an apartment, industry, and occupation were significantly associated with vitamin D levels. Based on the exceeding fraction, the armed forces showed the highest exceeding fraction level of 0.71.

Conclusions

Our results present the high exposure groups to sunlight across industries and occupations. Our results may provide a source for prioritizing occupational groups with a high risk of adverse health effects from sunlight exposure.

Poor Status of Vitamin D: A Survey of Area With Lowest Sunlight Radiation in Sichuan, China

OBJECTIVE

Vitamin D plays an important role in bone and mineral metabolism. Ultraviolet B (UVB) is the primary determinant for vitamin D synthesis. However, population-based data of vitamin D status was sparse in areas with sunlight deprivation in China. This study aimed to assess serum 25-hydroxyvitamin D [25(OH)D] levels among adult women in Sichuan basin with the lowest sunlight radiation in China, and the associations with sunlight exposure and age.

METHODS

In the context of the same ethnicity, similar latitude and lifestyle in sunlight-limited basin and sunlight-abundant plateau, 1,057 women in basin and 337 in plateau aged 29-95 years were included in this study, from November 2012 to February 2013. Daily sunlight exposure duration of previous month was obtained using questionnaires. Serum 25(OH)D was measured by enzyme-linked immunosorbent assay.

RESULTS

The prevalence of vitamin D severe deficiency [25(OH)D <30 nmol/L] and deficiency [30 ≤ 25(OH)D <50 nmol/L] was significantly higher in basin than plateau (21.85% vs. 10.09%, and 59.32% vs. 40.36%; P<0.0001). Women from basin exhibited lower serum 25(OH)D levels than those from plateau (40.66 ± 15.62 vs. 52.54 ± 19.94 nmol/L, P<0.0001). In basin, women more than 50 years old had higher 25(OH)D than younger counterparts, and 25(OH)D level of these groups was not associated with sunlight exposure duration. While in plateau, women younger than 60 years old had higher 25(OH)D than the older women. Furthermore, for those younger groups, women with long sunlight exposure (≥3 h daily) had higher 25(OH)D concentration than those with short sunlight exposure (<3 h daily). Serum PTH was negatively associated with 25(OH)D in basin, but not in plateau.

CONCLUSIONS

Alarmingly high prevalence of vitamin D deficiency was observed in women in sunlight-deprived basin in Sichuan. Only the vitamin D status of younger women from plateau with adequate solar radiation could benefit from sunlight exposure. Vitamin D supplementation and vitamin D-fortified food should be encouraged to improve vitamin D status for women living in sunlight-limited areas, or with old age.

Vitamin D: Insufficiency, Uncertainty and Achievability

Vitamin D is a prohormone that is essential to good health. As very few foods (fish, egg yolks, milk) are rich in vitamin D, the main source of the vitamin is synthesized in the skin in the presence of ultraviolet B rays from sunlight. However, due to Canada's northern latitude, sufficient amounts of vitamin D cannot be synthesized using sunlight during the fall and winter months and, consequently, there is a concern that many Canadians are not achieving adequate levels of vitamin D. A wide array of inconsistent evidence derived from serum and dietary assessments has been published and the results are inconclusive. This paper serves to outline the issues and challenges regarding nationwide intervention strategies such as fortification to increase vitamin D intake in the Canadian population. Given the potential for excessive intakes and the lack of informed Canadian data, implementing an intervention to increase vitamin D intake in the entire population may be irresponsible; however, further investigation of vitamin D intakes in certain subgroups of the Canadian population is warranted.

The roles of vitamin D and dietary calcium in nutritional rickets

The etiology and pathogenesis of nutritional rickets are becoming progressively clearer. Vitamin D deficiency has generally been considered the major or only player in the pathogenesis of nutritional rickets. However, recent research into calcium deficiency has now provided clinicians with reasons to investigate and manage patients with nutritional rickets more appropriately.

The important question when assessing cases of nutritional rickets is: “Is it calcium or vitamin D deficiency or both that play a major role in the pathogenesis of the disease?”

The case presentation in this review highlights the risk factors, clinical presentation and pathophysiology of nutritional rickets in a young South African black child from a semi-urban area in Johannesburg, a city with abundant sunshine throughout the year.

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Vitamin D and calcium deficiencies play synergistic roles in nutritional rickets.

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Dietary calcium intake of <300 mg/day increases the risk of nutritional rickets.

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Vitamin D status is worsened by dietary calcium deficiency itself.

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Marked elevation of 1,25-dihydroxyvitamin D is characteristic of calcium deficiency.

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Preventative strategies needed to decrease the prevalence of nutritional rickets.

Highly prevalence of vitamin D deficiency among Brazilian women of reproductive age

OBJECTIVE

Vitamin D has several metabolic functions and possible reproductive functions. This study aimed to determine the prevalence of vitamin D deficiency among Brazilian women of reproductive age, and to evaluate the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentrations and infertility causes.

SUBJECTS AND METHODS

This retrospective cross-sectional study evaluated data from a private Brazilian assisted reproduction center that were collected between January 1 and May 5, 2012. Serum 25(OH)D concentrations were measured and compared for infertile and fertile women. Concentrations of 25(OH)D that were < 20 ng/mL were defined as deficiency and concentrations of 21-30 ng/mL were defined as hypovitaminosis D.

RESULTS

Among the 369 evaluated women, 81.1% exhibited hypovitaminosis D and 32.0% exhibited deficiency. The infertile and control patients did not exhibit any significant differences in the prevalence of vitamin D deficiency (30.2% vs. 35%, respectively; p = 0.33) or in the mean 25(OH)D concentrations (24.3 ± 7.9 ng/mL vs. 23.8 ± 8.7 ng/mL, respectively; p = 0.51). Furthermore, there were no significant differences in the mean 25(OH)D concentrations among subgroups of patients with single infertility factors, or between these subgroups and the control group.

CONCLUSIONS

A high proportion of Brazilian women of reproductive age exhibited vitamin D deficiency, regardless of their fertility status. Thus, it may be useful to evaluate this population for vitamin D deficiency, although future studies are needed to determine whether this deficiency might affect the outcomes of treatments for infertility.