The Three Natural Forms of Vitamin D3
A physician friend asked me to clarify this issue...so here goes.
There are three forms of natural vitamin D3 and numerous synthetic analogs.
Vitamin D3 is made in the skin upon exposure to ultraviolet B radiation or light. Going out into the sun on a nice day does not mean you are exposed to much UVB light. Fog, smog, clouds and distance from the equator all influence the amount of UVB light that reaches the earth.
You CANNOT overdose on vitamin D3. If this were true, everyone who got a tan would be risking death. Vitamin D3 is not biologically active. It must be converted to other forms to have any affect on the body at all.
When vitamin D3 is made in the skin, taken as supplements, or ingested in meals (salmon, cod live oil), the hormone makes it way to the liver where it is converted to 25,VitD3. This form of vitamin D has some biological activity but not much.
25,VitD3 enters the blood and is converted to the ACTIVE form of vitamin D3 or 1,25VitD3 (calcitriol) in many, many tissues of the body. The conversion of 25,VitD3 to 1,25VitD3 is under tight biochemical control. In fact, 1,25VitD3 induces the synthesis of an enzyme that breaks down 1,25VitD3 into an inactive hormone. This feedback response insures that naturally made 1,25VitD3 never reaches toxic levels in the body.
When a physician administers calcitriol to a patient, the hormone is obviously already formed and fully active. In excessive concentrations, calcitriol can damage bone. But this is an artificial situation that probably doesn't happen naturally in the body due to biochemical controls.
This form of active vitamin D3 affects ALL tissues of the body simultaneously, while naturally made calcitriol is ONLY made in specific tissues under certain circumstances. This is known as the wisdom of the body.
Vitamin A enhances the effects of active vitamin D3, calcitriol, by inhibiting the enzyme that breaks it down. The hormones and their receptors also interact together to active genes that neither hormone can activate alone.
Both vitamin D3 and vitamin A deficiencies can properly be considered an epidemic in the world, affecting everything from eyesight to cancer to hypertension to diabetes to...you name it.
I hope this clears up the confusion. So get a tanning light, take vitamin A and calcium supplements and be happy.
Stay tuned...
Grouppe Kurosawa, Medicine in the Public Interest
(http://www.grouppekurosawa.com)
There are three forms of natural vitamin D3 and numerous synthetic analogs.
Vitamin D3 is made in the skin upon exposure to ultraviolet B radiation or light. Going out into the sun on a nice day does not mean you are exposed to much UVB light. Fog, smog, clouds and distance from the equator all influence the amount of UVB light that reaches the earth.
You CANNOT overdose on vitamin D3. If this were true, everyone who got a tan would be risking death. Vitamin D3 is not biologically active. It must be converted to other forms to have any affect on the body at all.
When vitamin D3 is made in the skin, taken as supplements, or ingested in meals (salmon, cod live oil), the hormone makes it way to the liver where it is converted to 25,VitD3. This form of vitamin D has some biological activity but not much.
25,VitD3 enters the blood and is converted to the ACTIVE form of vitamin D3 or 1,25VitD3 (calcitriol) in many, many tissues of the body. The conversion of 25,VitD3 to 1,25VitD3 is under tight biochemical control. In fact, 1,25VitD3 induces the synthesis of an enzyme that breaks down 1,25VitD3 into an inactive hormone. This feedback response insures that naturally made 1,25VitD3 never reaches toxic levels in the body.
When a physician administers calcitriol to a patient, the hormone is obviously already formed and fully active. In excessive concentrations, calcitriol can damage bone. But this is an artificial situation that probably doesn't happen naturally in the body due to biochemical controls.
This form of active vitamin D3 affects ALL tissues of the body simultaneously, while naturally made calcitriol is ONLY made in specific tissues under certain circumstances. This is known as the wisdom of the body.
Vitamin A enhances the effects of active vitamin D3, calcitriol, by inhibiting the enzyme that breaks it down. The hormones and their receptors also interact together to active genes that neither hormone can activate alone.
Both vitamin D3 and vitamin A deficiencies can properly be considered an epidemic in the world, affecting everything from eyesight to cancer to hypertension to diabetes to...you name it.
I hope this clears up the confusion. So get a tanning light, take vitamin A and calcium supplements and be happy.
Stay tuned...
Grouppe Kurosawa, Medicine in the Public Interest
(http://www.grouppekurosawa.com)
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