Grade 9
Vitamin D and Colds
Written by Caroline Yu
T
he common cold, also termed as Respiratory Tract Infection, is one of the most common infectious diseases in human of all ages. A growing number of studies have suggested that Vitamin D deficiency could cause the
common cold. The metabolism of Vitamin D and the factors cause the Vitamin D deficiency will be discussed in this paper. We will also involve the topic of how to prevent Vitamin D deficiency.
Introduction Vitamin D ( Vit D) is one of the most unexpected discoveries. Scientists found that Vit D reduced 50% of cancer incidences, and 90% of patients with the common cold recovered after taking Vit D. In addition, Vit D was also reported to play key roles in longevity. The common cold (we also termed it as Respiratory Tract Infection) is known as the most common infectious disease in human beings, including men and women of all ages. More and more research data showed that Vit D deficiency could cause the common cold. Why is Vit D deficiency linked to colds; what is the mechanism, and how can we prevent colds by supplementing with Vit D?
Discovery of Vitamin D In early 1918, Sir Edward Mellanby, a British medical doctor, found that cod liver oil could relieve rickets effectively, and rickets was caused by a dietary factor, a lack of Vitamin A (Vit A). In his later experiments, he processed cod liver oil through bubbling oxygen, which destroyed Vit A. And then, he still observed that the processed cod liver oil still could effectively relieve rickets. He was quite disappointed even though he knew that a nutrient deficiency caused the disease, but he could not figure out the reagent. Four years later, McCollum did repeat the same experiment. He found an unknown vitamin, which he termed it as “Vit D”, to contribute to the treatment of rickets. (History of the Discovery of Vitamin D and Its Active Metabolites)
Metabolism of vitamin D Vit D is one of the derivatives of steroids, which
can help calcium and phosphorus’s absorption, and also promote bone mineralization and musculoskeletal health. A new function of Vit D has been discovered claiming it was involved in various defense and immune cells including monoc y tes, macrophages, lymphoc y tes or epithelial cells. It also has been found that Vit D is related to lots of diseases such as infectious lung disease, asthma, and cancer. (Vitamin D and Health) Our bodies can not make Vit D3 themselves. Vit D3 is made in the skin from 7-dehydrocholesterol (7-DHC) under the influence of UV light or diet. The production of Vit D3 in the skin is not an enzymatic process. Instead, Vit D3 (also named cholecalciferol) is produced from 7-DHC though a two-step process by UV light (spectrum 280320 UVB) radiation from the sun. The intensity of UVB from sunlight varies according to season and latitude. Both UVB intensity and skin pigmentation level contribute to the rate of Vit D3 formation in our body. Another source of Vit D is our diet. Most foods with the exception of fatty fish contain little Vit D unless they are fortified. Fish Vit D is Vit D3, whereas D2 (also named ergocalciferol) is often used for fortification. D2 is produced by UVB irradiation of the ergosterol in plants and fungi (such as mushrooms). Vit D2 and D3 in are transported to the liver, where Vit D turned into 25-hydrocyvitamin D (25-OH(D)). 25-OH(D); the main circulation form of Vit D is biologically inactive until it converted into 1,25(OH)2D in the kidneys. (Vitamin D and the Immune System)
Relationships between vitamin D and 35