Final answer:
The body produces vitamin D when the skin is exposed to sunlight, creating a chain reaction starting with cholecalciferol formation and ending with the active form of vitamin D, calcitriol, crucial for bone health. Insufficient sunlight can cause vitamin D deficiency, leading to rickets or osteomalacia, hence vitamin D is added to some foods and supplements may be needed. It's also recommended to balance sun exposure with skin protection to prevent skin damage.
Step-by-step explanation:
The body produces its own vitamin D when the epidermal layer of human skin is exposed to UV radiation from sunlight. Specifically, a precursor of vitamin D3, known as cholecalciferol, is synthesized from cholesterol in the skin. This molecule is then transported to the liver where it's converted to calcidiol and subsequently to the active form, calcitriol, in the kidneys. Vitamin D is crucial for the absorption of calcium and phosphorous, essential for maintaining healthy bones.
Lack of sun exposure can lead to vitamin D deficiency, with serious health consequences such as rickets in children and osteomalacia in adults. To compensate for the lack of sun exposure, vitamin D is added to certain foods like milk and orange juice. However, people with darker skin or those living in areas with weaker sunlight may require longer exposure to the sun or may need to take supplements as prescribed by a doctor.
It is important to strike a balance between getting enough sunlight to produce vitamin D and protecting the skin from excessive UV radiation, which can lead to skin damage and increase the risk of skin cancer. The American Academy of Dermatology advises getting vitamin D through foods or supplements rather than prolonged sun exposure.