Since 1824, doctors have recommended cod liver oil, a potent source of Vitamin D, to build strong b...
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Since 1824, doctors have recommended cod liver oil, a potent source of Vitamin D, to build strong bones in children who are not exposed to much sunlight. Other dietary sources for this important vitamin include: fatty fish, eggs, fortified milk and orange juice. All Vitamin D begins with sunlight. For example, the Vitamin D we get from fish comes from algae they ate that made Vitamin D from sunlight. We also make our own Vitamin D from sunlight. When your skin is exposed to the sun, ultraviolet rays convert a form of cholesterol in the upper layer of skin into Vitamin D. All Vitamin D has to be converted into an active form by your liver and kidneys before your body can use it. The primary job of this active form, called calcitriol, is to regulate your body's levels of calcium and phosphorous. Calcitriol stimulates your body to absorb calcium, which also increases phosphorous absorption. It also stimulates the breakdown of old bone, releasing calcium and phosphorous, and the building of new bone. Where you live, the amount of sunlight each day, and how long your skin is exposed all affect how much Vitamin D you produce. People with more melanin or pigment in their skin need longer exposure than those with less melanin, which acts as a light filter.