Calcitriol: promotes the absorption of calcium and phosphorus from food in the gut and reabsorption of calcium in the kidneys – this increases the flow of calcium in the bloodstream. This subsequently increases bone formation and healthy mineralization. This prevents hypocalcemic tetany àlow calcium condition in which patients have overactive neurological reflexes, spasms of the hands and feet, cramps and spasms of the voice box (larynx). Calcitriol also plays a key role in the maintenance of many organ systems.
Vitamin D had been implicated in the following.
. and more…
Various forms of vitamin D
It is produced by invertebrates (animals without a spine, vertebral column), fungus and plants in response to sunlight (UV irradiation). Humans and other vertebrates do not produce vitamin D2. We don’t know much about what vitamin D2 does in invertebrates. We know that ergosterol is a good absorber of ultraviolet radiation which can damage DNA, RNA and protein; consequently many scientists believe it may serve as sunscreen that protects organisms from sunlight damage.
|Vitamin D Metabolism (http://2.bp.blogspot.com)|
· Vitamin D3, cholecalciferol (made from 7-dehydrocholesterol).
Vitamin D3 is made in the skin when 7-dehydrocholesterol reacts with ultraviolet light at
270-300 nm wavelengths – peak vitamin D3production occurs between 295-297 nm. It is only when the UV index is greater than 3 that these UVB wavelengths are present.
Which is more important for humans, vitamins D2 or D3?
Sunlight and vitamin D requirements.
Of course the recommendation for 15 mins of unprotected sun exposure does increase a persons’ risk for skin cancer. Therefore, you have to use your judgement and make an educated choice for yourself. For instance, my goal is to have 10-15 mins of unprotected sun exposure on my face, arms and neck (occasionally chest or back) during the summer months, not during peak sun hours (i.e. 1300 – 1700) twice per week in order to get adequate. The rest of the time in the sun, PROTECTION (i.e. sunscreen or clothing). I am hoping to get my vitamin D levels measured just before summer and then again after summer to see the effect. Unfortunately, at this time in Canada, Vitamin D blood work is not covered by OHIP, so I’ll have to pay the $40 or so (x 2).
Well worth it though, seeing as how prevalence of Vitamin D deficiency are widespread in temperate areas. The NHANES survey (USA) found that 9% (7.6 million) of children, were vitamin D deficient (defined as less than 15 ng/mL of blood), while another 61 percent, or 50.8 million, were vitamin D insufficient (15 to 29 ng/mL). This finding was shocking to health professionals across the US.
How much vitamin D do I need?
- Infants 0-1 y – 400 IU
- Children 1 – 8 y – 600 IU
- Children, Adolescents and Adults 9 – 70 y – 600 IU
- Adults > 70 y – 800 IU
- Pregnancy and Lactation – 600 IU
Therefore, Best Sources of Vitamin D.
5) Vegetarian source: Certified Organic Shitake Mushrooms (dried even higher) D2 form.
6) Fortified foods (dairy, dairy alternatives and grains).