The sunshine vitamin, Vitamin D, is important in innate immunity, protecting against infections, tumors and autoimmune diseases. Maintenance of adequate Vitamin D levels is extremely important for human health. During autumn and winter, when sunlight is weak, vitamin D levels and immunity defenses against viral infection decrease, spurring the need for vitamin D supplements. In this study, changes in blood levels of vitamin D of the young (age range: 20-30), middle (age range: 31-59), and elderly (age range: 60-86) were compared. The elderly were found to have the lowest vitamin D level. Researchers found that toll-like receptor 7 (TRL7), which regulates virus immunity, is most affected by vitamin D deficiency. Dr. John Wherry of the Journal of Leukocyte Biology said that “the study shows that the lack of vitamin D could have a role in the seasonally higher rates of infection.”