Vitamin D: Maintains normal blood levels of calcium and phosphorus
• Promotes bone mineralization
• May reduce high blood pressure
• Helps build strong bones
What is Vitamin D?
Vitamin D, calciferol, is a fat-soluble vitamin. It is known as the “sunshine” vitamin because it is formed in the body by the action of the sun’s ultraviolet rays on the skin. Vitamin D is converted in the kidneys to the hormone calcitrol, which is actually the most active form of vitamin D. The effects of this hormone are targeted at the intestines and bones.
Vitamin D requirements increase with age, while the ability of skin to convert sunlight into Vitamin D decreases. In addition the ability of the kidneys to convert calcidiol to its active form also decreases with age, prompting the need for increased Vitamin D supplementation in elderly individuals. One billion people in the world are currently Vitamin D deficient.
What does Vitamin D do?
The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, thereby helping to form and maintain strong bones. It promotes bone mineralization in conjunction with a number of other vitamins, minerals, and hormones. Without vitamin D, bones can become thin, brittle, soft, or misshapen. Vitamin D prevents rickets in children and osteomalacia in adults, which are skeletal diseases that result in defects that weaken bones.
Cardiovascular: Research indicates that vitamin D may play a role in preventing or reversing coronary disease. Vitamin D deficiency is associated with an increase in high blood pressure and cardiovascular risk. When researchers monitored the vitamin D levels, blood pressure and other cardiovascular risk factors of 1739 people, of an average age of 59 years for 5 years, they found that those people with low levels of vitamin D had a 62% higher risk of a cardiovascular event than those with normal vitamin D levels.
What are signs of Vitamin D deficiency?
The use of sunscreen with a sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin. To avoid vitamin D deficiency dermatologists recommend supplementation along with sunscreen use.
The reduced pigmentation of light-skinned individuals tends to allow more sunlight to be absorbed even at higher latitudes, thereby reducing the risk of vitamin D deficiency. However, at higher latitudes (above 30°) during the winter months, the decreased angle of the sun's rays, reduced daylight hours, protective clothing during cold weather, and fewer hours of outside activity, diminish absorption of sunlight and the production of vitamin D. Because melanin acts like a sun-block, prolonging the time required to generate vitamin D, dark-skinned individuals, in particular, may require extra vitamin D to avoid deficiency at higher latitudes.
Vitamin D deficiency can result from inadequate intake coupled with inadequate sunlight exposure, disorders that limit its absorption, conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders, or, rarely, by a number of hereditary disorders. Deficiency results in impaired bone mineralization, and leads to bone softening diseases, rickets in children and osteomalacia in adults, and possibly contributes to osteoporosis.
• The risk of overdose is not present with natural exposure to sunlight, because the skin's capacity to produce vitamin D is self-limiting (skin production is thought to reflect the dose of vitamin D to which our evolution optimised human biology). In contrast, care should be given to limit oral intake for infants to no more than 1000 IU (25 mcg) daily, or for adults no more than 10,000 IU (250 mcg) daily.
• If you are pregnant or lactating consult a health care practitioner before using Vitamins D.
• Occasional side effects reported with large doses of Vitamin D include a disorder known as hypercalcemia, which causes calcium deposits in soft tissues. Signs of the disorder include headache, weakness, nausea, vomiting, confusion, kidney problems and constipation. Consult a health care practitioner if you experience any of these symptoms while taking Vitamin D.