What is vitamin D?

Vitamin D is part of the fat-soluble compounds, which are stored in the liver and released in small doses whenever necessary. Therefore, it is not necessary to take them on a regular basis, such as through foods. 
Vitamin D comes in two forms: ergocalciferol, which can be taken through food, and cholecalciferol, which is synthesized by the body. 

What is the role of vitamin D?

Vitamin D is mainly synthesized by the body, through the absorption of sunlight by the skin. This vitamin is regulates calcium metabolism in the body and is therefore useful in of bone calcification activity. Vitamin D also helps maintain normal levels of calcium and phosphorus in the blood. 

Which foods are rich in vitamin D? 

Vitamin D is scarcely present in food (some fatty fish, milk and dairy products, eggs, liver and green vegetables). The only exception is in cod liver oil. 
Vitamin D is stored in large amounts in the body and must be present for building stronger bones in special situations such as growth, pregnancy, and breastfeeding. 

What is the daily requirement of vitamin D?

The daily requirement of vitamin D varies according to age. It starts from 200 units a day for children and goes up to 400 units in adults (ages 51-70 years old), and comes to a recommended 600 units for those over the age of 70.  

Vitamin D deficiency

Vitamin D deficiency can have negative effects on the calcification of bones ranging from rickets for children, various types of bone deformations to osteomalacia, which occurs when the bone structure is externally combined but the bones are softened due to insufficient mineral content. Lack of vitamin D can also weaken the teeth and make them more vulnerable to decay. 

Excessive vitamin D intake

Excessive vitamin D intake can cause calcification in various organs, resulting in vomitingdiarrhea and muscle spasms.