Vitamin D

Vitamin D is a white crystalline substance that helps in maintaining the normal functioning of parathormone and the level of calcium and phosphorus in the body.

Function
- Vitamin D plays a crucial role in the regulation of calcium and phosphorus levels in the body. It enhances the absorption of calcium and phosphorus from the small intestine.
- It promotes the reabsorption of calcium and phosphorus in the kidneys, preventing their loss in urine.
- Vitamin D also stimulates the release of parathormone from the parathyroid glands. Parathormone helps to increase the level of calcium in the blood by releasing it from bones when necessary.
- It aids in the mineralization of bones and teeth by ensuring the proper utilization of calcium and phosphorus.

Sources
- Sunlight: The body can produce vitamin D when the skin is exposed to sunlight. Ultraviolet B (UVB) rays from the sun convert a cholesterol derivative in the skin into vitamin D.
- Food sources: Vitamin D can be obtained from certain foods such as fatty fish (salmon, mackerel, sardines), cod liver oil, fortified dairy products (milk, yogurt, cheese), fortified cereals, and egg yolks.

Deficiency
- Deficiency of vitamin D can lead to rickets in children and osteomalacia in adults. Both conditions are characterized by weak and brittle bones due to impaired mineralization.
- In severe cases, vitamin D deficiency can result in skeletal deformities, muscle weakness, and an increased risk of fractures.
- Low levels of vitamin D have also been associated with an increased risk of certain diseases, including autoimmune disorders, cardiovascular diseases, and certain types of cancer.

Conclusion
In conclusion, vitamin D is a white crystalline substance that is essential for maintaining the normal functioning of parathormone and regulating the levels of calcium and phosphorus in the body. It is obtained from sunlight exposure and certain food sources, and its deficiency can lead to various skeletal and non-skeletal health issues.