Vitamin D (also known as calciferol) is a fat-soluble vitamin that plays a crucial role in various physiological processes in the body. It is unique among vitamins because the body can produce it when the skin is exposed to sunlight.
Key points:
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Functions: It is essential for the maintenance of healthy bones. It helps regulate the absorption of calcium and phosphorus in the intestines. It supports the immune system, and is involved in cell growth, differentiation, and various cellular processes.
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Sources: Sunlight on skin can produce vitamin D. The amount of sunlight needed depends on factors such as skin type, geographic location, and time of day. Dietary sources of vitamin D include fatty fish (e.g., salmon, mackerel), cod liver oil, and fortified products.
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Deficiency: Vitamin D deficiency can lead to weakened bones, increased risk of fractures, and conditions like rickets in children and osteomalacia in adults.
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Toxicity: Excessive vitamin D can result in hypercalcemia (elevated blood calcium levels) and other health problems.
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Recommended Dietary Allowance (RDA): The RDA for vitamin D varies by age, sex, and life stage. It is expressed in international units (IU) or micrograms (mcg).
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Supplementation: Some individuals, especially those with limited sun exposure or at higher risk of deficiency, may require vitamin D supplementation.
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Testing and Monitoring: Blood tests can measure the levels of 25-hydroxyvitamin D, the main circulating form of vitamin D, to assess an individual's vitamin D status.