| Vitamin D2 (ergocalciferol) is the form often | | | | D, which is then used by the body. Since vitamin |
| added to milk and other foods, and most often | | | | D can only be produced by the skin during the |
| used in nutrition supplement. Vitamin D3 | | | | summer months via this route, the body’s |
| (cholecalciferol) is made by the body and is found | | | | ability to store vitamin D is extremely essential. |
| in some foods. Active vitamin D functions as a | | | | The remaining 10% of the recommended intake |
| hormone as it sends a message to the intestines | | | | of vitamin D is supplied by diet. |
| to increase the absorption of calcium and | | | | Factors such as the season of the year, latitude, |
| phosphorus; as such vitamin D is critically | | | | time of day, cloud cover, smog, and sun screens |
| important for the development, growth, and | | | | all affect the amount of ultraviolet ray exposure |
| maintenance of a healthy body, from birth until | | | | we receive from the sun and can reduce our |
| death, in humans. The major biologic function of | | | | supply of vitamin D. In countries where exposure |
| vitamin D is to maintain normal blood levels of | | | | to the sun is reduced by head to feet clothing for |
| calcium and phosphorus. It helps to form and | | | | religious or other reasons, vitamin D under |
| maintain strong bones by promoting calcium | | | | nutrition is a problem. Elderly people who stay |
| absorption. It also works alongside a number of | | | | inside and have poor diets may also have a sub |
| other vitamins, minerals, and hormones to | | | | clinical deficiency of vitamin D. |
| promote bone mineralisation. Without vitamin D, | | | | An initial exposure of about 10-15 minutes to |
| bones can become thin, brittle, or misshapen. | | | | sunlight allows adequate time for Vitamin D |
| Vitamin D sufficiency prevents rickets in children | | | | synthesis and should be followed by application of |
| and osteomalacia in adults, two forms of skeletal | | | | a sunscreen with a sun protection factor SPF of |
| diseases that weaken bones. | | | | at least 15 to protect the skin. This is because |
| Sun exposure is perhaps the most important | | | | sunscreens with an SPF of 8 or greater will block |
| source of vitamin D because exposure to sunlight | | | | UV rays that produce vitamin D, but it is still |
| provides most humans with their vitamin D | | | | important to routinely use sunscreen to help |
| requirement. About 90% of the daily | | | | prevent skin cancer and other negative |
| recommended intake of 10 micrograms or 400 | | | | consequences of excessive sun exposure. Ten to |
| international units is obtained from the action of | | | | fifteen minutes of sun exposure at least two |
| sunlight on the skin. UV rays (particularly UVB | | | | times per week to the face, arms, hands, or |
| rays) from the sun trigger an inactive form of | | | | back without sunscreen is usually sufficient to |
| vitamin D to be formed in the skin. This is taken | | | | provide adequate vitamin D. It is very important |
| up by the blood stream, to be stored in muscles | | | | for individuals with limited sun exposure to include |
| and body fat; it also passes through the liver and | | | | good sources of vitamin D in their diet. |
| kidneys and becomes an active form of vitamin | | | | |