With the flu and cold season upon us, it is important to have optimal Vitamin D levels. According to Dr. Michael F. Holick, Ph.D., MD, author of the "The Vitamin D Solution," Vitamin D could prevent:  heart disease, common cancers, stroke, infectious diseases from influenza to tuberculosis, type 1 and 2 diabetes, dementia, depression, insomnia, muscle weakness, joint pain, fibromyalgia, osteoarthritis, rheumatoid arthritis, osteoporosis, psoriasis, multiple sclerosis and hypertension.

Dr. Holick states in his book that 3 out of 4 Americans are deficient in Vitamin D.  He also clarifies that Vitamin D is actually a secosteroid hormone that directly or indirectly targets more than 2000 genes or about 6% of the human genome. 

Below are medical journal references from Dr. Hugo Rodier about Vitamin D:

“Vitamin D Insufficiency May Be Linked to Allergies, Asthma,”
J. Family Practice News May 1st 2010, page 32 

“Vitamin D deficiency in urban youth with asthma,”
J. Pediatrics 2010;156:A3

“Low Serum 25-Hydroxyvitamin D Levels Are Associated with Increased All-Cause Mortality Risk in a General Population: the Troms study,”
European J. Endocrinology 2010;162:935

“Association of A1C Levels With Vitamin D Status in U.S. Adults: Data from the National Health and Nutrition Examination Survey;” check vitamin D levels in diabetics.
J. Diabetes Care 2010;33:1236  

“Randomized Trial of Vitamin D Supplementation to Prevent Seasonal iInfluenza A in Schoolchildren,”
American J. Clinical Nutrition 2010;91:1255

“Vitamin D and the Magic Mountain: The Anti-Infectious Role of the Vitamin,”
J. Pediatrics 2010;156:698 

The risk of respiratory infections, including TB, influenza, pneumonia, and other upper and lower respiratory tract infections, is much greater in children with vitamin D deficiency (serum 25(OH)D <10 ng/mL). This inverse relationship between vitamin D status (low in winter and high in summer) and infection is what was found when rickets was epidemic. Recent experiments have shed light on the immune-enhancing properties of vitamin D that combat M tuberculosis and other infectious agents. The concept prevalent in the late 19th century that infections caused rickets can now be reversed, because mechanisms exist by which vitamin D deficiency leads to increased infections.