Vitamin D

What is Vitamin D?

Vitamin D is a fat-soluble vitamin also known as Cholecalciferol (D2) when found in foods of animal origin and as Ergocalciferol (D2), which is produced by the action on light on yeast. Vitamin D is commonly known as the Sunshine vitamin. Vitamin D is obtained through the diet and even by exposure to sunlight!

Function

Vitamin D promotes the body's absorption of calcium, which is essential for the normal development and maintenance of healthy teeth and bones. Calcium is also important to nerve cells, including the brain. Vitamin D also helps maintain adequate blood levels of calcium and Phosphorus. It prevents Rickets in children and Osteomalacia in adults

Symptoms of Deficiency

In children, the signs can be observed by unnatural limb posture, excessive sweating of the head, a delayed ability to stand up and knock-knees or bow legs. In adults, bone pain in the ribs and lower limbs, muscular weakness and spasms and brittle, or easily broken bones are tell tale signs of a Vitamin D deficiency.
Causes of Deficiency
Not taking in enough meat, poultry and fish as well as a lack of dairy products will cause a deficiency. Note also that insufficient exposure to the sun will cause this too. Although if a person receives plenty of sunshine then dietary sources of Vitamin D are not required.

Dietary sources of Vitamin D

Foods that contain the highest levels of Vitamin D are Cod liver oil, kippers, mackerel, canned salmon, sardines, tuna, eggs and milk. Attention should also be paid to fortified foods such as margarines and breakfast cereals, which have good levels of the vitamin.

Excessive Vitamin D intake

Vitamin D is extremely toxic in excessive dosages. Excessive doses of vitamin D can result in increased calcium absorption from the intestinal tract. This may cause increased calcium re-absorption from the bones, leading to elevated levels of calcium in the bloodstream. Elevated blood calcium may then cause calcium deposition in soft tissues such as the heart and lungs. This can reduce their ability to function effectively
It is therefore not advisable to take any amount over and above the Recommended Intake. Symptoms of overdose include headaches, weakness, nausea & vomiting, constipation and kidney stones

The Recommended Daily allowance for men and women living in the U.K. and being of generally good health is 10 µg with supplements of Vitamin D not to exceed 10µg