Long-Term Exposure to Ambient PM2.5, Sunlight, and Obesity: A Nationwide Study in China

BackgroundAccumulated researches revealed that both fine particulate matter (PM2.5) and sunlight exposure may be a risk factor for obesity, while researches regarding the potential effect modification by sunlight exposure on the relationship between PM2.5 and obesity are limited. We aim to investigate whether the effect of PM2.5 on obesity is affected by sunlight exposure among the general population in China.MethodsA sample of 47,204 adults in China was included. Obesity and abdominal obesity were assessed based on body mass index, waist circumference and waist-to-hip ratio, respectively. The five-year exposure to PM2.5 and sunlight were accessed using the multi-source satellite products and a geochemical transport model. The relationship between PM2.5, sunshine duration, and the obesity or abdominal obesity risk was evaluated using the general additive model.ResultsThe proportion of obesity and abdominal obesity was 12.6% and 26.8%, respectively. Levels of long-term PM2.5 ranged from 13.2 to 72.1 μg/m3 with the mean of 46.6 μg/m3. Each 10 μg/m3 rise in PM2.5 was related to a higher obesity risk [OR 1.12 (95% CI 1.09-1.14)] and abdominal obesity [OR 1.10 (95% CI 1.07-1.13)]. The association between PM2.5 and obesity varied according to sunshine duration, with the highest ORs of 1.56 (95% CI 1.28-1.91) for obesity and 1.66 (95% CI 1.34-2.07) for abdominal obesity in the bottom quartile of sunlight exposure (3.21-5.34 hours/day).ConclusionLong-term PM2.5 effect on obesity risk among the general Chinese population are influenced by sunlight exposure. More attention might be paid to reduce the adverse impacts of exposure to air pollution under short sunshine duration conditions.

Can we Depend on Sunshine for Vitamin D? A mini review and historical perspective

Worldwide studies have confirmed that vast population globally is suffering from vitamin D deficiency that can be linked to not only calcium and bone metabolic disorders, but also to diabetes, hypertension, rheumatoid arthritis and multiple sclerosis. Traditionally, inadequate sunlight exposure was implicated in Vitamin D deficiency. However recent studies from the Middle East and other countries suggest the contrary and thus unreliable. Test based diagnostics remain the most desirable way to prevent and treat Vitamin D deficiency rather than relying on sunshine.

Knowledge and Attitude towards Vitamin D among Saudi Female university students at Princess Nourah University

Aims: The purpose of this study was to assess the knowledge and attitude towards vitamin D and sunlight exposure among female university students. Study Design: Cross Sectional study design. Place and Duration of Study: The study was conducted among 500 female Saudi students in Princess Nourah Bint Abdulrahman University (PNU). Methodology: A self-administered questionnaire was used to assess the knowledge about vitamin D sources, health benefits and effects of vitamin D deficiency and assessing the attitude towards vitamin D and sunlight exposure. Results: The present study recognized that health college students (52.7%) had better knowledge than non-health college students (47.3%). Although PNU students had good knowledge about vitamin D, only 6.0% of them knew the current recommended daily dose. Female students showed good behavior and attitude in terms of high frequency of sunlight exposure daily (34.8%). Educational institutions were the main sources of information about vitamin D (43%). Hot weather (54.8%) and fear of pigmentation (51.2) were the main reasons for limited sunlight exposure among students. Conclusion: There was a good level of knowledge (52.2%) about vitamin D sources, benefits and effects of vitamin D deficiency among female students. In fact, health college students had better knowledge about vitamin D than non-health college students. Hot weather (54.8%) and fear of pigmentation (51.2%) were the main barriers to sunlight exposure.

Dietary vitamin D intake among university students and their habits concerning daily sunlight exposure – a cross-sectional study

Aim: To evaluate students’ dietary vitamin D intake according to characteristics and habits concerning daily sunlight exposure. Methods: The study included 403 students of the University of Rijeka, Croatia that fulfilled questionnaire about their characteristics, habits, physical activity, supplement use, diet, and their daily sunlight exposure. For assessing diet quality, the Dietary inflammatory index (DII®) was used. Results: Average dietary vitamin D intake was 2.76 μg/day, statistically highest among men (p<0.01), medical sciences universities’ students (p<0.01), students with obesity (p=0.03), highly physically active (p=0.02) and smokers (p=0.01). Major dietary vitamin D sources were fish (42%, p<0.01) and meat and meat products (31%). Students that more frequently expose themselves to the sunlight were mostly men, overweight, moderately physically active, dietary supplements users, and had a diet with more anti-inflammatory potential, higher dietary vitamin D intake and its major dietary sources. Those who rarely and never used a sunscreen had a more anti-inflammatory diet and higher vitamin D and its major food sources intakes. Diet with more pro-inflammatory potential had students that rarely or never directly expose themselves to the sunlight, likewise the students that frequently used sunscreen. Those subgroups also had the lowest dietary vitamin D intake. Conclusions: The average dietary vitamin D intake by investigated university students satisfied only the fifth of the recommended daily vitamin D intake. Students with habits that can influence the lower synthesis of vitamin D may increase the risk of diseases related to bone health, immunity and inflammation in their future life. Provided results about students’ habits of their exposure to the sunlight might be useful for public health messages toward sufficient sunlight exposure, diet quality with more anti-inflammatory potential, vitamin D supplements use, and vitamin D deficiency prevention.