Calciferol

Also known as Vitamin D

Vitamin D

Vitamin D is a name given to two fat-soluble compounds; calciferol (vitamin D2 ) and cholecalciferol (vitamin D3 ). They are now known to be hormones, but continue to be grouped with vitamins because of historical misclassification. Vitamin D3 plays an essential role in the metabolism of calcium and phosphorus in the body and prevents rickets in children. A plentiful supply of 7-dehydrocholesterol, the precursor of vitamin D3 , exists in human skin and needs only to be activated by a moderate amount of ultraviolet light (less than a half hour of sunlight) to become fully potent. Rickets is usually caused by a lack of exposure to sunlight rather than a dietary deficiency, although dietary deficiencies can result from malabsorption in the small intestine caused by conditions such as sprue or colitis. Rickets can be prevented and its course halted by the intake of vitamin D2 (found in irradiated yeast and used in some commercial preparations of the vitamin) or vitamin D3 (found in fish liver oils and in fortified milk). Symptoms of vitamin D deficiency in children include bowlegs, knock knees, and more severe (often crippling) deformations of the bones. In adults deficiency results in osteomalacia, characterized by a softening of the bones. Excessive vitamin D consumption can result in toxicity. Symptoms include nausea, loss of appetite, kidney damage, and deposits of insoluble calcium salts in certain tissues. The recommended daily dietary allowance for cholecalciferol is 5 to 10 micrograms (200 to 400 IU) depending upon age and the availability of sunlight. Fortified cow's milk supplies 400 IU per quart (422 IU per liter).

Functions:

• Anti-rachitic factor (prevents rickets)
• Builds bone and teeth
• Transport of Calcium
• Absorption of phosphate(phosphorus) (intestinal and renal)

Deficiency symptoms:

• Painless epiphyseal enlargement
• Beading of ribs
• Bowed legs
• Skull bossing
• Thoracic deformities
• Impaired mineralization of bone matrix
• Rickets in children
• Osteomalacia in adults
• Soft bones and teeth
• Spontaneous fractures
• Bone curvature

What is Vitamin D?

Vitamin D is fat-soluble like vitamins A, E and K are. You will find it in an oil form if you take it as a supplement and it is sometimes derived from cod-liver oil.

Where is it found?

It is referred to as the sunshine vitamin because it can be synthesized in the skin from sunlight, in which case, it need not be obtained from food sources. No other vitamin acts in this way. It is also, in its active form, a hormone by the name of cacitrol.

Vitamin D needs to go through two processes in order to end up as cacitrol - it firstly needs to go to the liver and then through to the kidneys.

Why is it needed?

Its main role is to regulate phosphorous and calcium which are two minerals. These minerals are responsible for hardening of bones and aid in normal growth and development.

Vitamin D works by stimulating the gut into absorbing calcium and also stimulates the kidneys into reabsorbing some calcium, that way, excess calcium need not be excreted through the urine and can be used when needed.

What happens if you are deficient?

If you become Vitamin D deficient then the body's regulation of phosphorous and calcium is affected, the body begins to produce an increased amount of a hormone which removes calcium from the bones.

The disease "rickets" which is normally seen in children rather than adults is the result of calcium deficiency due to vitamin D deficiency. Rickets in adults is called "osteomalacia" where the bones become so soft they can no longer support weight and start to bow and buckle.

What conditions has it been used to treat?

Primary:

• Coeliac disease (if deficient)
• Crohn's disease
• Rickets

Secondary:

• Alcoholism
• Diabetes
• Migraine
• Headache
• Osteomalacia

How much is normally taken?

400 IU daily is adequate but you should not need to supplement with this vitamin as the body produces its own vitamin D through exposure to sunlight.

Are there any contraindications or side effects?

Those who already suffer with high calcium levels in the blood or those with hyperparathyroidism should be wary about taking vitamin D supplements, and should consult a nutritionally qualified practitioner.

If you take too much Vitamin D over a long period of time it can lead to headaches, weight loss, increased urination, diarrhoea, the development of kidney stones and - in rare cases - death.