Alice explains that despite living in sunny areas, many people worldwide are deficient in vitamin D, a nutrient crucial for cell-to-cell communication in the body. She mentions that 75% of Americans, regardless of where they live, are vitamin D deficient. Studies have also shown that 100% of people in the Middle East and 95% of Indian women who spend most of their time outside are deficient in vitamin D. Alice emphasizes that vitamin D is not just for bones and is needed throughout one's life. It affects brain cognition, cardiac health, and more.