Primary source of Vitamin D: sunlight or nutrition?

This study reviews the existing literature on whether sunlight or nutrition is the main source of vitamin D and explores the factors contributing to vitamin D deficiency in tropical regions. The key findings include urbanization, ethnicity, sunavoidance, religion, and nutrition as causes for the high prevalence of vitamin D deficiency in tropical areas. While sunlight is considered the main source of vitamin D, factors such as air pollution, sun-avoidance behaviors, and the clothing style of certain religions can limit sunlight absorption. Moreover, limited access to vitamin D-rich foods and low consumption of fortified foods contribute to the deficiency. The study suggests further research on the role of nutrition as a potential main contributor to vitamin D deficiency in tropical areas.