Nutritionist Leyla Muedin discusses the significance of vitamin D, especially during the winter months in northern regions. She explains how the lack of sunlight exposure from October to April can lead to vitamin D deficiency, which is linked to various health issues including autoimmune diseases. Leyla emphasizes the importance of vitamin D for immune function, bone health, and overall well-being. She also offers practical tips on obtaining sufficient vitamin D through supplementation and dietary sources, as well as by safely getting sunlight exposure. The episode highlights recent research on the effects of vitamin D deficiency during childhood development and its potential long-term impacts on health.