A number of studies have suggested a role for vitamin D in innate immunity, including the prevention of respiratory tract infections (RTIs).  Researchers from the University of Colorado (Colorado, USA) analyzed data from the Third National Health and Nutrition Examination Survey, which involved 18,883 adults and adolescents between 1988 and 1994.  The team found that people with the lowest average levels of Vitamin D in the blood were about 40% more likely to have a recent RTI, as compared to those with the highest Vitamin D blood levels .  Further, low Vitamin D levels in people with asthma were associated with a five-time greater risk of RTI; and among COPD patients, RTIs were twice as common among those with Vitamin D deficiency. 

Therapeutic Daily Dosing: Consult an anti-aging physician to determine the dosing that is appropriate for your medical needs.