About Vitamin D Deficiency
Vitamin D is essential for the development and maintenance of healthy bones. Early in life, Vitamin D is necessary for bone development and growth. Later in life, Vitamin D is necessary for bone maintenance.
Vitamin D is normally made in our skin or ingested in the foods we eat. In our skin Vitamin D is made by the photoconversion of 7-Dehydrocholesterol (a provitamin) to Previtamin D3 Previtamin D3 undergoes thermal isomerization to Vitamin D3 which is picked up by serum proteins and carried first to the liver where it undergoes a hydroxylation to 25-hydroxy Vitamin D and then 25-Hydroxy Vitamin D is carried to the kidneys where a second hydroxylation occurs which makes the active form of the vitamin 1,25 calciferol.
When we ingest foods containing Vitamin D3, like certain fish oils, or milks or cereals fortified with Vitamin D3, the D3 is transported through the gut and carried by proteins for the necessary hydroxylations by the liver and kidneys(ref.) There are several disturbing reports that some foods purported to contain Vitamin D; in fact, do not.
Vitamin D is stored in the body fat ant the major circulating form of vitamin D, 25 (OH)D has a circulating half life of approximately 2-3 weeks. Both of these in combination can help maintain a person’s vitamin D status in the normal range throughout the winter if they obtain enough vitamin D during the spring, summer and fall from sun exposure. However, it should be appreciated that body fat can sequester vitamin D, and that we and others have shown that obese people are more prone to vitamin D deficiency because of the irreversible sequestration of vitamin D in the body fat. It also should be recognized that you would need to raise your blood levels of 25 (OH)D into the 100-150 nmol/L (40-60 ng/ml) range by the end of the summer in order to store enough vitamin D in your body fat and have enough 25 (OH)D in the circulation to sustain you throughout the winter. Since most children and adults never reach this blood level, it is necessary for them to increase their dietary intake of vitamin D and to take a vitamin D supplement throughout the winter to maintain their 25 (OH)D levels above 75/nmol/L which most experts agree is a healthy preferred level.
It is well documented that increase in sensible sun exposure and or vitamin D intake improves overall health and well being. Exposure to ultraviolet B radiation or increasing intake of Vitamin D maximizes bone health in children; helps prevent osteoporosis in adults; decreases risk of common autoimmune diseases including multiple sclerosis, rheumatoid arthritis, Crohn’s disease and type 1 diabetes; reduces risk of serious deadly cancers including cancers of the colon, breast, prostate, ovary, esophagus and others; and decreases risk of cardiovascular heart disease. In addition, it is well documented that exposure to solar ultraviolet radiation was an effective method of treating patients with tuberculosis. Recent revelations have documented that it is necessary to increase blood levels of vitamin D either from solar ultraviolet irradiation, artificial ultraviolet irradiation or increasing vitamin D intake for enhancing the immune system to destroy the bacterium that causes tuberculosis. Thus, sensible exposure to ultraviolet B radiation from sun or lamps is an effective method of maintaining adequate vitamin D levels to sustain health throughout life.
