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Introdução: Associada com uma considerável quantidade de doenças crônicas, agudas e mais recentemente, a Covid 19, a deficiência de vitamina D tem se tornado cada vez mais prevalente até em regiões de baixa latitude. Objetivo geral: Identificar e caracterizar a associação entre clima, estilo de vida e áreas verdes com os status de vitamina D em mulheres. Objetivos específicos: Avaliar a associação entre concentrações séricas de 25(OH)D e fatores relacionados ao estilo de vida em uma amostra de mulheres brasileiras que vivem na latitude 21º 80' S. Analisar a associação entre verde residencial em áreas urbanas e concentrações séricas de 25(OH)D em moradoras de uma cidade brasileira interiorana de médio porte e de clima tropical. Analisar a associação entre verde residencial, estilo de vida e concentrações séricas de 25(OH)D em moradoras de cidades de clima temperado ao sul da Inglaterra. Método: Foram realizados dois estudos epidemiológicos que analisaram a influência da dieta e exposição à luz solar no status de vitamina D. Idade, variáveis antropométricas, cor da pele e estado pós-menopausa foram medidos como potenciais fatores de confusão. O estudo transversal foi realizado com 101 mulheres com 35 anos ou mais que avaliou a associação entre a concentração sérica de 25(OH)D e a exposição à radiação ultravioleta, estilo de vida e depressão. O estudo longitudinal de 1 ano avaliou o status de vitamina D em 365 mulheres caucasianas e asiáticas, na pré-menopausa e pós-menopausa, residentes na região sul do Reino Unido. Como indicador da variável áreas verdes, foi calculado o Índice de Vegetação por Diferença Normalizada. Foram usados modelos de regressão múltipla e logística para analisar a associação entre as variáveis, além de testes não paramétricos. Os estudos resultaram em três artigos que estão na presente tese. Resultados: No primeiro artigo, no estudo transversal, mulheres mais velhas tiveram uma concentração significativamente maior de 25(OH)D do que as mulheres mais jovens (p = 0,013), bem como maior exposição à RUV (p = 0,01) e menor IMC (p = 0,005). Esses achados são independentes de outros fatores de confusão medidos. No segundo artigo, observou-se uma associacao positiva estatisticamente significativa entre a exposicao ao indice de vegetacao circundante residencial abaixo da mediana e a prevalencia de niveis insuficientes de 25(HO)D (P=0,03).No terceiro artigo, no estudo de coorte, as participantes que viviam em áreas mais verdes eram mais propensas a ter status de vitamina D melhorado (RR: 1,51, IC 95%: 1,13- 2,02), assim como, as que eram mais expostas à radiação ultravioleta (RR: 2,05, IC 95%: 1,44 - 2,92). Contudo, no modelo totalmente ajustado, as variáveis etnia e hormônio paratireóideo permaneceram significantes, p < 0,001 e p = 0,003. Conclusão: Foram encontradas associações entre vitamina D, estilo de vida, saúde mental e áreas verdes importantes para um panejamento urbano e social de incentivo a atividades ao ar livre. Contudo, uma análise de mediação que elucide como as áreas verdes contribuem para maiores níveis de vitamina D através do tempo de exposição à luz solar é necessário.

Introduction: Associated with a considerable amount of chronic and acute diseases and more recently, Covid 19, vitamin D deficiency has become increasingly prevalent even in low latitude regions. General objective: To identify and characterize the association between climate, lifestyle and green areas with vitamin D status in women. Specific objectives: To evaluate the association between serum concentrations of 25(OH)D and factors related to lifestyle in a sample of Brazilian women living at latitude 21º 80' S. To analyze the association between residential green in urban areas and serum concentrations of 25(OH)D in residents of a medium-sized country town in Brazil with a tropical climate. To analyze the association between residential greenery, lifestyle and serum concentrations of 25(OH)D in residents of temperate cities in the south of England. Method: Two epidemiological studies were performed that analyzed the influence of diet and sunlight exposure on vitamin D status. Age, anthropometric variables, skin color and postmenopausal status were measured as potential confounders. A cross-sectional study was carried out with 101 women aged 35 years or older that evaluated the association between serum 25(OH)D concentration and exposure to ultraviolet radiation, lifestyle and depression. The 1-year longitudinal study assessed the vitamin D status of 365 premenopausal and postmenopausal Caucasian and Asian women residing in the southern part of the UK. As an indicator of the green areas variable, the Vegetation Index by Normalized Difference was calculated. Multiple and logistic regression models were used to analyze the association between variables, in addition to non-parametric tests. The studies resulted in three articles that are in this thesis. Results: In the first article, in the cross-sectional study, older women had a significantly higher concentration of 25(OH)D than younger women (p = 0.013), as well as greater exposure to UVR (p = 0.01) and lower BMI (p = 0.005). These findings are independent of other measured confounders. In the second article, a statistically significant positive association was observed between exposure to the surrounding residential vegetation index below the median and the prevalence of insufficient levels of 25(HO)D (P=0.03). cohort, participants who lived in greener areas were more likely to have improved vitamin D status (RR: 1.51, 95% CI: 1.13-2.02), as were those who were more exposed to ultraviolet radiation (RR: 2.05, 95% CI: 1.44 - 2.92). However, in the fully adjusted model, the variables ethnicity and parathyroid hormone remained significant, p < 0.001 and p = 0.003. Conclusion: Association was found between vitamin D, lifestyle, mental health and important green areas for urban and social planning to encourage outdoor activities. However, a mediation analysis that elucidates how green areas contribute to higher levels of vitamin D through exposure time to sunlight is needed.

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This study evaluated the differences in vitamin D3 synthesis in two different latitudes throughout 1 year using an in vitro model, which simulates cutaneous vitamin D photoproduction. Borosilicate ampoules containing 7-dehydrocholesterol (7-DHC) were exposed to sunlight hourly throughout the daylight hours, 1 day per month for a year, in Fortaleza (latitude 03° 43' 01" S-LAT3° S) and Sao Paulo (latitude 23° 32' 53" S-LAT23° S). Later, vitamin D3 and photoisomers of 7-DHC (tachysterol and lumisterol) were measured by a high-performance liquid chromatography system (HPLC). Vitamin D synthesis weighted UV radiation (UVBVitD) and solar zenith angle (SZA) were calculated during the same periods for both latitudes. Vitamin D3 synthesis occurred throughout the year in both locations, as expected in latitudes lower than 35°. Median of photoconversion to vitamin D3 through the year was higher in LAT3°S [median (IQR): LAT 3°S 4.1% (6.0); LAT 23°S 2.9% (4.5); p value = 0.020]. Vitamin D3 production strongly correlated with UV-B (LAT3° S, r = 0.917; p < 0.0001 and at LAT23° S, r = 0.879; p < 0.0001) and SZA (LAT3° S, r = - 0.924; p < 0.0001 and in LAT23°S, r = - 0.808; p < 0.0001). Vitamin D3 production starts later in LAT23° S, especially in winter. Lowest percentages were observed in June in both cities, although, compared to LAT3° S, in LAT 23° S the conversion was over 50% lower in the winter period. Cloudiness impaired photoproduction of Vitamin D3 even in summer months in both latitudes. Our results provide data to help guide medical recommendations for sensible sun exposure to promote the cutaneous production of vitamin D3 at different latitudes, seasonality, time of day and cloudiness status in Brazil.

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Ultraviolet radiation (UVR) plays a key role in several biological functions, including human health. Skin exposure to UVR is the main factor in vitamin D photoconversion. There is also evidence relating low levels of vitamin D with certain internal cancers, mainly colon, breast and prostate, as well as other diseases. Several epidemiological studies have shown an inverse relationship between the above-mentioned diseases and latitude, in accordance with the ultraviolet radiation latitudinal gradient. The aim of this study is to determine whether UV irradiance levels in the southern South America are sufficient to produce suitable levels of vitamin D year around. For this purpose, vitamin D photoconversion weighted-irradiance was analyzed between S.S. de Jujuy (24.17°S, 65.02°W) and Ushuaia (54° 50'S, 68° 18'W). In addition to irradiance, skin type and area of body exposed to sunlight are critical factors in vitamin D epidemiology. Due to a broad ethnic variability, it was assumed that the skin type in this region varies between II and V (from the most to the less sensitive). All sites except South Patagonia indicate that skin II under any condition of body area exposure and skin V when exposing head, hands, arms and legs, would produce suitable levels of vitamin D year round (except for some days in winter at North Patagonian sites). At South Patagonian sites, minimum healthy levels of vitamin D year round can be reached only by the more sensitive skin II type, if exposing head, hands, arms and legs, which is not a realistic scenario during winter. At these southern latitudes, healthy vitamin D levels would not be obtained between mid May and beginning of August if exposing only the head. Skin V with head exposure is the most critical situation; with the exception of the tropics, sun exposure would not produce suitable levels of vitamin D around winter, during a time period that varies with latitude. Analyzing the best exposure time during the day in order to obtain a suitable level of vitamin D without risk of sunburn, it was concluded that noon is best during winter, as determined previously. For skin type II when exposing head, exposure period in winter varies between 30 and 130 min, according to latitude, except for South Patagonian sites. During summer, noon seems to be a good time of day for short periods of exposure, while during leisure times, longer periods of exposure without risk of sunburn are possible at mid-morning and mid-afternoon. At 3 h from noon, solar zenith angles are almost the same for sites between the tropics and North Patagonia, and at 4 h from noon, for all sites. Then, in these cases, the necessary exposure periods varied slightly between sites, only due to meteorological differences.

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Studies of voluntary exposure to ultraviolet-B (UVB) radiation from the sun in the field were conducted in the southern US and Jamaica for 15 species of lizards and snakes occupying various habitats. Species were sorted into four zones of UVB exposure ranging from a median UV index of 0.35 for zone 1 to 3.1 for zone 4. Guidelines for UVB exposure in captivity of these and species occupying similar light environments are presented. Data for most species were collected during mid-day during the spring breeding season, which appeared to be the time of maximum exposure. For two species of Sceloporus studied more intensively there was significant variation of exposure among times of the day and among seasons. So, all-day studies over the entire active season are necessary to fully understand the pattern of natural exposure for a particular diurnal species. Environmental and body temperature and thermoregulation as well as UVB/vitamin D photoregulation influences exposure to UVB. Regressions allowing the inter-conversion of readings among some meters with different detector sensitivities are presented. Readings of natural sunlight predict the same photobiosynthetic potential for vitamin D as the same reading from artificial sources whose wavelength distribution within the UVB band of the source is comparable to that of sunlight. Research approaches to further increase our understanding of vitamin D and UVB use and requirements for squamate reptiles in captivity are outlined.

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