Vitamin D- the legend continues! A question

[Guest guest]

I wonder, does the sunscreen cut out the light rays, visible or UV, that help to synthesize the vitamin D?

 

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Susan Mc Cary

holistic-health

27 March 2004 07:40

Vitamin D- the legend continues!

 

Re the vitamin D discussion, I take a daily supplement of calcium and magnesium with vitamin D, of course I get my fair amount of sun (of course with suncreen), living in Miami Beach!

Regards to all, Susan.

 

 

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[Guest guest]

Good question, Stewart. I believe in the use of sunscreen if intending to spend a long time in the sun (work, beach or whatever) but have often wondered about the use of sunscreen every day. Worth looking into.

Debbie

 

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Stewart Wilson

holistic-health

Sunday, March 28, 2004 8:20 AM

Re: Vitamin D- the legend continues! A question

 

 

I wonder, does the sunscreen cut out the light rays, visible or UV, that help to synthesize the vitamin D?

 

-

Susan Mc Cary

holistic-health

27 March 2004 07:40

Vitamin D- the legend continues!

 

Re the vitamin D discussion, I take a daily supplement of calcium and magnesium with vitamin D, of course I get my fair amount of sun (of course with suncreen), living in Miami Beach!

Regards to all, Susan.

 

 

Finance Tax Center - File online. File on time.

[Guest guest]

Of course, as an ex-biochemist I ought to have been able to answer my own question!

In "Biochemistry" by Leininger (1975) we find:

"...it is now known that 7-dehydrocholesterol in the skin is the natural precursor of cholecalciferol [Vitamin D] in man; the conversion requires irradiation of the skin by sunlight."

But he doesn't give the wavelength - visible, infrared or ultraviolet!

A few lines further down:

"Vitamin D preparations available commercially are products of the ultraviolet irradiation of ergosterol from yeast. About 20 micrograms of vitamin D are required by an adult daily. The vitamin can be stored in sufficient amounts in the liver for a single dose to suffice for some weeks. As with vitamin A, excessive intake of vitamin D causes the bones to become fragile and to undergo multiple fractures, suggesting that both vitamins play a role in the biological transport and deposition of calcium."

A warning there, perhaps not to overdose on D or A.

Of course, that was written 30 years ago, and more work must have been done since then.

It is tantalizing that the optimum wavelength of the irradiation of the skin by sunlight is not given in this particular text (my latest!) but I wouldn't mind betting that it's in the UV somewhere.

So it looks as if sunscreens might well inhibit vitamin D synthesis. Anyone know of any later findings?

Stewart

 

 

-

Debbie Brand

holistic-health

28 March 2004 02:24

Re: Vitamin D- the legend continues! A question

 

Good question, Stewart. I believe in the use of sunscreen if intending to spend a long time in the sun (work, beach or whatever) but have often wondered about the use of sunscreen every day. Worth looking into.

Debbie

 

-

Stewart Wilson

holistic-health

Sunday, March 28, 2004 8:20 AM

Re: Vitamin D- the legend continues! A question

 

 

I wonder, does the sunscreen cut out the light rays, visible or UV, that help to synthesize the vitamin D?

 

-

Susan Mc Cary

holistic-health

27 March 2004 07:40

Vitamin D- the legend continues!

 

Re the vitamin D discussion, I take a daily supplement of calcium and magnesium with vitamin D, of course I get my fair amount of sun (of course with suncreen), living in Miami Beach!

Regards to all, Susan.

 

 

Finance Tax Center - File online. File on time.

[Guest guest]

More recent but still not `today': Encycloepedia Britannica, 1992 [sunlight], `... Although ultraviolet light constitutes only a very small proportion of the total radiation this component is extremely important. It produces vitamin D through the activation of ergosterol. It is also an important germicidal agent. ...' I haven't come across anything on sunscreen yet.

Debbie

 

 

 

-

Stewart Wilson

holistic-health

Monday, March 29, 2004 7:07 AM

Re: Vitamin D- the legend continues! A question

 

 

Of course, as an ex-biochemist I ought to have been able to answer my own question!

In "Biochemistry" by Leininger (1975) we find:

"...it is now known that 7-dehydrocholesterol in the skin is the natural precursor of cholecalciferol [Vitamin D] in man; the conversion requires irradiation of the skin by sunlight."

But he doesn't give the wavelength - visible, infrared or ultraviolet!

A few lines further down:

"Vitamin D preparations available commercially are products of the ultraviolet irradiation of ergosterol from yeast. About 20 micrograms of vitamin D are required by an adult daily. The vitamin can be stored in sufficient amounts in the liver for a single dose to suffice for some weeks. As with vitamin A, excessive intake of vitamin D causes the bones to become fragile and to undergo multiple fractures, suggesting that both vitamins play a role in the biological transport and deposition of calcium."

A warning there, perhaps not to overdose on D or A.

Of course, that was written 30 years ago, and more work must have been done since then.

It is tantalizing that the optimum wavelength of the irradiation of the skin by sunlight is not given in this particular text (my latest!) but I wouldn't mind betting that it's in the UV somewhere.

So it looks as if sunscreens might well inhibit vitamin D synthesis. Anyone know of any later findings?

Stewart

 

 

-

Debbie Brand

holistic-health

28 March 2004 02:24

Re: Vitamin D- the legend continues! A question

 

Good question, Stewart. I believe in the use of sunscreen if intending to spend a long time in the sun (work, beach or whatever) but have often wondered about the use of sunscreen every day. Worth looking into.

Debbie

 

-

Stewart Wilson

holistic-health

Sunday, March 28, 2004 8:20 AM

Re: Vitamin D- the legend continues! A question

 

 

I wonder, does the sunscreen cut out the light rays, visible or UV, that help to synthesize the vitamin D?

 

-

Susan Mc Cary

holistic-health

27 March 2004 07:40

Vitamin D- the legend continues!

 

Re the vitamin D discussion, I take a daily supplement of calcium and magnesium with vitamin D, of course I get my fair amount of sun (of course with suncreen), living in Miami Beach!

Regards to all, Susan.

 

 

Finance Tax Center - File online. File on time.