October 2006 follow up: "Is melanoma simply a Vitamin D deficiency cancer?"

TO: All melanoma researchers, doctors, and patients.

Doesn't anyone else find it curious that, of all the cancers being
touted by researchers as Vitamin D deficiencies, melanoma is not one of
them?

James Semmel
Albuquerque, New Mexico



reference:
http://www.mpip.org/bb/shtml/351407.shtml
Last month's follow up to the 3rd annual discussion: "Is melanoma
simply a Vitamin D deficiency cancer?"

James Semmel wrote:
> TO: All melanoma researchers, doctors, and patients.
>
> Doesn't anyone else find it curious that, of all the cancers being
> touted by researchers as Vitamin D deficiencies, melanoma is not one of
> them?

James,

I remember your posting about this a month ago. I
found it intriguing but, knowing very little about melanoma,
I wasn't able to contribute anything, and still can't.

Isn't anyone researching this? It does, on the
surface of it, seem like Vitamin D and melanoma
could be related since both have to do with exposure
to the sun. However I recall the posting you made was
the exact opposite of received wisdom - which is that
_too much_ exposure to the sun is a cause of
melanoma, not too little.

Have you made any progress in researching this?

Alan

Hi Alan,

Good to hear from you again! (Did you ever read some of Dr. Rossi's
publications about shoes and their effect on posture? I recall we were
in a discussion about how shoes cause Alzheimer's disease.)

That's right, too much sun exposure could cause melanoma via the
resultant deficiency in Vitamin D. Bear in mind that the body's
protective mechanism called tanning inhibits the synthesis of Vitamin D
in the skin to prevent toxicity.

In other words, the prevention of melanoma is an optimization problem
involving sun exposure. Doctors and researchers from the last
quarter-century, however, advised minimizing sun exposure, dubious and
deadly advice.

james



Alan Meyer wrote:
> James Semmel wrote:
> > TO: All melanoma researchers, doctors, and patients.
> >
> > Doesn't anyone else find it curious that, of all the cancers being
> > touted by researchers as Vitamin D deficiencies, melanoma is not one of
> > them?
>
> James,
>
> I remember your posting about this a month ago. I
> found it intriguing but, knowing very little about melanoma,
> I wasn't able to contribute anything, and still can't.
>
> Isn't anyone researching this? It does, on the
> surface of it, seem like Vitamin D and melanoma
> could be related since both have to do with exposure
> to the sun. However I recall the posting you made was
> the exact opposite of received wisdom - which is that
> _too much_ exposure to the sun is a cause of
> melanoma, not too little.
>
> Have you made any progress in researching this?
>
> Alan

James Semmel wrote:
> Hi Alan,
>
> Good to hear from you again! (Did you ever read some of Dr. Rossi's
> publications about shoes and their effect on posture? I recall we were
> in a discussion about how shoes cause Alzheimer's disease.)

Ah yes. I had forgotten. You are the shoe guy.

I'm afraid I'm not qualified to comment on the vitamin D
theory.

Good luck to you though.

Alan

Thanks Alan!

james


Alan Meyer wrote:
> James Semmel wrote:
> > Hi Alan,
> >
> > Good to hear from you again! (Did you ever read some of Dr. Rossi's
> > publications about shoes and their effect on posture? I recall we were
> > in a discussion about how shoes cause Alzheimer's disease.)
>
> Ah yes. I had forgotten. You are the shoe guy.
>
> I'm afraid I'm not qualified to comment on the vitamin D
> theory.
>
> Good luck to you though.
>
> Alan

On 10 Oct 2006 12:21:05 -0700, "Alan Meyer" <ameyer2@yahoo.com> wrote:

>James Semmel wrote:
>> TO: All melanoma researchers, doctors, and patients.
>>
>> Doesn't anyone else find it curious that, of all the cancers being
>> touted by researchers as Vitamin D deficiencies, melanoma is not one of
>> them?
>
>James,
>
>I remember your posting about this a month ago. I
>found it intriguing but, knowing very little about melanoma,
>I wasn't able to contribute anything, and still can't.
>
>Isn't anyone researching this? It does, on the
>surface of it, seem like Vitamin D and melanoma
>could be related since both have to do with exposure
>to the sun. However I recall the posting you made was
>the exact opposite of received wisdom - which is that
>_too much_ exposure to the sun is a cause of
>melanoma, not too little.
>
About 20 minutes full body exposure to the sun's UVB radiation on a
sunny summer day causes the synthesis of 10 000 - 25 000 IU of vitamin
D3 in the skin of light skinned people. Dark skinned people need 120
minutes to produce the same amount of vitamin D3. After that the
sunlight starts destroying the already formed vitamin D3 in the skin
at the same rate than new vitamin D3 is being formed. So for light
skinned people there is no reason stay in the sun longer than 20
minutes (120 minutes for dark skinned people) to get the maximum daily
dose of vitamin D3. Staying in the sun 10-20 minutes on sufficient
number of sunny summer days will guarantee more than adequate supply
of vitamin D. Anything longer that 20 minutes is not necessary, and
could be harmful.


--
Matti Narkia

Matti Narkia wrote:
> >
> About 20 minutes full body exposure to the sun's UVB radiation on a
> sunny summer day causes the synthesis of 10 000 - 25 000 IU of vitamin
> D3 in the skin of light skinned people. Dark skinned people need 120
> minutes to produce the same amount of vitamin D3. After that the
> sunlight starts destroying the already formed vitamin D3 in the skin
> at the same rate than new vitamin D3 is being formed. So for light
> skinned people there is no reason stay in the sun longer than 20
> minutes (120 minutes for dark skinned people) to get the maximum daily
> dose of vitamin D3. Staying in the sun 10-20 minutes on sufficient
> number of sunny summer days will guarantee more than adequate supply
> of vitamin D. Anything longer that 20 minutes is not necessary, and
> could be harmful.
>
There seem to be many variables unaddressed here. Variations in "light"
skin, "full body" exposure, sunny or partly cloudy, morning or mid-day
or afternoon, spring or summer or fall and last but not least,
latitude.

Also, what would a "sufficient number of sunny summer days" be? And
does the adequate supply then last through the fall, winter and spring?

Thanks,

John

On 11 Oct 2006 12:45:34 -0700, "JohnHace" <johnh@amcoex.com> wrote:
>
>Matti Narkia wrote:
>> >
>> About 20 minutes full body exposure to the sun's UVB radiation on a
>> sunny summer day causes the synthesis of 10 000 - 25 000 IU of vitamin
>> D3 in the skin of light skinned people. Dark skinned people need 120
>> minutes to produce the same amount of vitamin D3. After that the
>> sunlight starts destroying the already formed vitamin D3 in the skin
>> at the same rate than new vitamin D3 is being formed. So for light
>> skinned people there is no reason stay in the sun longer than 20
>> minutes (120 minutes for dark skinned people) to get the maximum daily
>> dose of vitamin D3. Staying in the sun 10-20 minutes on sufficient
>> number of sunny summer days will guarantee more than adequate supply
>> of vitamin D. Anything longer that 20 minutes is not necessary, and
>> could be harmful.
>>
>There seem to be many variables unaddressed here. Variations in "light"
>skin,

The range for the time required for maximun daily vitamin D dose is
20-120 minutes for the lightest (white) skin to the darkest (black)
skin. Intermediate skin colors are somewhere within this time range. A
simplistic approach to estimate the time needed by a person to get
his/her maximum daily dose of vitamin D would be to assess where
his/her skin fits in the range white - black using some numerical
value, say between 0 (white) and 1 (black), and use that number to
interpolate between 20 and 120 minutes. This will of course give only
a very rough estimate, but frankly currently I'm not aware of any more
accurate method.

>"full body" exposure,

Naked. I thought that that would be obvious. Close enough
approximation is not too big swimming suit.

>sunny or partly cloudy,

I did write "sunny summer day". You get some reduced UVB-radiation
even on partly cloudy summer day, but the maximum dose may be
decreased or/and time needed for it may be lengthened.

>morning or mid-day or afternoon,

Midday for the maximum dose, although a reduced dose may be obtained
in the morning and afternoon.

>spring or summer or fall and last but not least, latitude.
>
Summer is the best. Outside 40th latitudes far in the north and south
there is not enough UVB-radiation in the winter to promote cutaneous
synthesis of vitamin D. The length of this "vitamin D winter" depends
on the latitude. In tropics you naturally get sufficient UVB-radiation
throughout the year. See the studies by Webb et al. and Engelsen et al
in the references later in this message

>Also, what would a "sufficient number of sunny summer days" be?
>
It has been estimated that the bodies of healthy men use 3000 - 5000
IU of vitamin D/d, if it is available. So to retain the vitamin D
status (serum 25(OH)D concentration), one needs in average get that
amount per day from whatever sources. Food is almost neglible source
of vitamin D (fish is the best) and you cannot get 3000 - 5000/d from
food. You can approximate the sufficient number of days, when you know
that the maximum dose from exposure to the sun is 10 000 - 25 000 IU/d
(you can use 10 000 in calculations), and that you need to get in
average about 3000 - 5000 IU/d (say 4000 IU/d). Rough estimate is that
you would need to get the maximum dose (20 minutes full body exposure,
if you are white) every 2.5 days in the midday in a sunny summer day
or more often, if you cannot do it in midday, time is shorter or you
don't get full body exposure. This is for optimal vitamin D levels.
Many people get less and are doing ok, but risk of some chronic
diseases may increase if the average daily dose is much too low. And
old people synthetize vitamin D in the skin much less effectively than
young people, they may produce only 25% of the amount younger people
can produce. Therefore older people may need supplements throughout
the year.

>And does the adequate supply then last through the fall, winter and spring?

It depends on the latitude. In tropical areas cutaneous synthesis of
vitamin D is possible throughout the year, but in far north and south
there is no cutaneous synthesis during "vitamin D winter", whose
length depends on the latitude. IMHO, in these areas it's sensible to
supplement with art least 2000 IU/d during "vitamin D winter" to
prevent vitamin D level falling too much in the winter (some vitamin D
researcers thinj that big seasonal fluctuations in vitamin D level
could be harmful). Again I would recommend that you browse through the
studies by Webb et al. and Engelsen et al in the references later in
this message


You may find following references useful:

Vieth R.
Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and
safety.
Am J Clin Nutr. 1999 May;69(5):842-56. Review.
PMID: 10232622 [PubMed - indexed for MEDLINE]
<http://www.ajcn.org/cgi/content/full/69/5/842>

Vieth R, Chan PC, MacFarlane GD.
Efficacy and safety of vitamin D3 intake exceeding the lowest observed
adverse effect level.
Am J Clin Nutr. 2001 Feb;73(2):288-94.
PMID: 11157326 [PubMed - indexed for MEDLINE]
<http://www.ajcn.org/cgi/content/full/73/2/288>

Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ.
Human serum 25-hydroxycholecalciferol response to extended oral dosing
with cholecalciferol.
Am J Clin Nutr. 2003 Jan;77(1):204-10. Erratum in: Am J Clin Nutr.
2003 Nov;78(5):1047.
PMID: 12499343 [PubMed - indexed for MEDLINE]
<http://www.ajcn.org/cgi/content/full/77/1/204>
<http://www.ajcn.org/cgi/content/full/78/5/1047> (Erratum)

Webb AR, Kline L, Holick MF.
Influence of season and latitude on the cutaneous synthesis of vitamin
D3: exposure to winter sunlight in Boston and Edmonton will not
promote vitamin D3 synthesis in human skin.
J Clin Endocrinol Metab. 1988 Aug;67(2):373-8.
PMID: 2839537 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrie ve&dopt=abstractplus&list_uids=2839537>

Engelsen O, Brustad M, Aksnes L, Lund E.
Daily duration of vitamin D synthesis in human skin with relation to
latitude, total ozone, altitude, ground cover, aerosols and cloud
thickness.
Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90.
PMID: 16354110 [PubMed - indexed for MEDLINE]
<http://www.bioone.org/perlserv/?request=get-abstract&issn=0031-8655&volume=81&page=1287>

Check out also the pages

VitD Duration of Vitamin D Synthesis in Human Skin
<http://zardoz.nilu.no/~olaeng/fastrt/VitD.html>

VitD-ez Easy Duration of Vitamin D Synthesis in Human Skin
<http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html>

mentioned in the above abstract.


References about vitamin D and cancer:

Holick MF.
Vitamin D: its role in cancer prevention and treatment.
Prog Biophys Mol Biol. 2006 Sep;92(1):49-59. Epub 2006 Mar 10. Review.
PMID: 16566961 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=16566961>

Gombart AF, Luong QT, Koeffler HP.
Vitamin D compounds: activity against microbes and cancer.
Anticancer Res. 2006 Jul-Aug;26(4A):2531-42. Review.
PMID: 16886661 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=16886661>

Spina CS, Tangpricha V, Uskokovic M, Adorinic L, Maehr H, Holick MF.
Vitamin D and cancer.
Anticancer Res. 2006 Jul-Aug;26(4A):2515-24. Review.
PMID: 16886659 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=16886659>

Garland CF, Garland FC, Gorham ED, Lipkin M, Newmark H, Mohr SB,
Holick MF.
The role of vitamin D in cancer prevention.
Am J Public Health. 2006 Feb;96(2):252-61. Epub 2005 Dec 27. Review.
PMID: 16380576 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=16380576>

Giovannucci E.
The epidemiology of vitamin D and cancer incidence and mortality: a
review (United States).
Cancer Causes Control. 2005 Mar;16(2):83-95. Review.
PMID: 15868450 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=15868450>

Holick MF.
Vitamin D: importance in the prevention of cancers, type 1 diabetes,
heart disease, and osteoporosis.
Am J Clin Nutr. 2004 Mar;79(3):362-71. Review. Erratum in: Am J Clin
Nutr. 2004 May;79(5):890.
PMID: 14985208 [PubMed - indexed for MEDLINE]
<http://www.ajcn.org/cgi/content/full/79/3/362>


--
Matti Narkia

Matti Narkia wrote:
> Anything longer that 20 minutes is not necessary, and
> could be harmful.

But isn't the production of D self-limiting? If not, I should be able to
live in a cave for the next 30 years without any D problems -- and
donate enough D to take care of several Norwegian librarians --
considering the time I've spent in the desert, beach, and high altitude
sun.

I.P.

On Wed, 11 Oct 2006 22:13:47 -0700, "I.P. Freely"
<fuhgheddaboutit@noway.nohow> wrote:

>Matti Narkia wrote:
>> Anything longer that 20 minutes is not necessary, and
>> could be harmful.
>
>But isn't the production of D self-limiting?

That's exactly what I wrote, if you bother to read my message. After
20 minutes in the sun as much vitamin D is destroyed in the skin by
sunlight as is produced by the stimulation by the sun's UVB-radiation.
Therefore for vitamin D production any longer stay in the sun than 20
minutes at the time is useless, waste of time and may harm the skin.


--
Matti Narkia

On Thu, 12 Oct 2006 09:54:41 +0300, Matti Narkia <mna@mbnet.fi> wrote:

>On Wed, 11 Oct 2006 22:13:47 -0700, "I.P. Freely"
><fuhgheddaboutit@noway.nohow> wrote:
>
>>Matti Narkia wrote:
>>> Anything longer that 20 minutes is not necessary, and
>>> could be harmful.
>>
>>But isn't the production of D self-limiting?
>
>That's exactly what I wrote, if you bother to read my message. After
>20 minutes in the sun as much vitamin D is destroyed in the skin by
>sunlight as is produced by the stimulation by the sun's UVB-radiation.
>Therefore for vitamin D production any longer stay in the sun than 20
>minutes at the time is useless, waste of time and may harm the skin.

More information about this in the articles

Webb AR, DeCosta BR, Holick MF.
Sunlight regulates the cutaneous production of vitamin D3 by causing
its photodegradation.
J Clin Endocrinol Metab. 1989 May;68(5):882-7.
PMID: 2541158 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=2541158>

"Exposure to sunlight initiates the formation of vitamin D3 in
skin as the UV B radiation in the solar spectrum causes the
photoconversion of 7-dehydrocholesterol to previtamin D3. A
heat-induced isomerization then converts previtamin D3 to
vitamin D3 over a period of days. A number of irradiation
products of vitamin D3 are known to form upon irradiation with
high intensity UV radiation, but the effect of subsequent
exposures to sunlight on the vitamin D3 formed in skin is not
known. To investigate this phenomenon, human skin containing
vitamin D3 was exposed to sunlight in Boston. A model system of
[3H]vitamin D3 in methanol was also used to study the effects
of sunlight on vitamin D3 throughout the year. Vitamin D3
proved to be exquisitely sensitive to sunlight, and once formed
in the skin, exposure to sunlight resulted in its rapid
photodegradation to a variety of photoproducts, including 5,6-
transvitamin D3, suprasterol I, and suprasterol II."

and

Vieth R.
Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and
safety.
Am J Clin Nutr. 1999 May;69(5):842-56. Review.
PMID: 10232622 [PubMed - indexed for MEDLINE]
<http://www.ajcn.org/cgi/content/full/69/5/842>

"At least 4 studies support the concept that one full-body
exposure to sunlight can be equivalent to an oral vitamin D
intake of 250 µg (10000 IU). Stamp (39) compared oral vitamin D
to the effects of ultraviolet light treatment sessions and
found that the rise in 25(OH)D was the same in subjects treated
with ultraviolet light as in those given 250 µg (10000 IU)
vitamin D/d. In a study of institutionalized elderly, Davie et
al (28) exposed 600 cm2, {approx}5% of skin surface, to
ultraviolet light treatments over a 2–3-mo period and compared
the resulting 25(OH)D concentrations with those achieved with
oral vitamin D doses. They calculated a production of vitamin D
in the skin equivalent to 0.045 nmol •d-1•cm-2 exposed skin.
This is equivalent to 10.9 µg (435 IU) vitamin D/d for 5% of
skin surface. An almost identical protocol was followed
recently by Chel et al (30), confirming the relative effects of
light and supplementation on 25(OH)D concentration (28). If
these results for the elderly are extrapolated to total body
surface area, it works out to 218 µg (8700 IU) vitamin D/d that
can be acquired by the elderly. More recently, Holick (40)
presented data that compared blood vitamin D concentrations in
subjects taking vitamin D orally with those given ultraviolet
light exposure. The ultraviolet treatment produced blood
vitamin D concentrations comparable with an intake of 250–625
µg (10000–25000 IU) vitamin D/d orally.

Ultraviolet exposure beyond the minimal erythemal dose does not
increase vitamin D production further. The ultraviolet-induced
production of vitamin D precursors is counterbalanced by
degradation of vitamin D and its precursors. The concentration
of previtamin D in the skin reaches an equilibrium in white
skin within 20 min of ultraviolet exposure (41). Although it
can take 3–6 times longer for pigmented skin to reach the
equilibrium concentration of dermal previtamin D, skin
pigmentation does not affect the amount of vitamin D that can
be obtained through sunshine exposure (42). However, aging does
lower the amount of 7-dehydrocholesterol in the skin and lowers
substantially the capacity for vitamin D production (43, 44)."


--
Matti Narkia

On Thu, 12 Oct 2006 03:31:46 +0300, Matti Narkia <mna@mbnet.fi> wrote:

>On 11 Oct 2006 12:45:34 -0700, "JohnHace" <johnh@amcoex.com> wrote:
>>
>>Matti Narkia wrote:
>>> >
>>> About 20 minutes full body exposure to the sun's UVB radiation on a
>>> sunny summer day causes the synthesis of 10 000 - 25 000 IU of vitamin
>>> D3 in the skin of light skinned people. Dark skinned people need 120
>>> minutes to produce the same amount of vitamin D3. After that the
>>> sunlight starts destroying the already formed vitamin D3 in the skin
>>> at the same rate than new vitamin D3 is being formed. So for light
>>> skinned people there is no reason stay in the sun longer than 20
>>> minutes (120 minutes for dark skinned people) to get the maximum daily
>>> dose of vitamin D3. Staying in the sun 10-20 minutes on sufficient
>>> number of sunny summer days will guarantee more than adequate supply
>>> of vitamin D. Anything longer that 20 minutes is not necessary, and
>>> could be harmful.
>>>
>>There seem to be many variables unaddressed here. Variations in "light"
>>skin,
>
>The range for the time required for maximun daily vitamin D dose is
>20-120 minutes for the lightest (white) skin to the darkest (black)
>skin. Intermediate skin colors are somewhere within this time range. A
>simplistic approach to estimate the time needed by a person to get
>his/her maximum daily dose of vitamin D would be to assess where
>his/her skin fits in the range white - black using some numerical
>value, say between 0 (white) and 1 (black), and use that number to
>interpolate between 20 and 120 minutes. This will of course give only
>a very rough estimate, but frankly currently I'm not aware of any more
>accurate method.
>
>>"full body" exposure,
>
>Naked. I thought that that would be obvious. Close enough
>approximation is not too big swimming suit.
>
>>sunny or partly cloudy,
>
>I did write "sunny summer day". You get some reduced UVB-radiation
>even on partly cloudy summer day, but the maximum dose may be
>decreased or/and time needed for it may be lengthened.
>
>>morning or mid-day or afternoon,
>
>Midday for the maximum dose, although a reduced dose may be obtained
>in the morning and afternoon.
>
>>spring or summer or fall and last but not least, latitude.
>>
>Summer is the best. Outside 40th latitudes far in the north and south
>there is not enough UVB-radiation in the winter to promote cutaneous
>synthesis of vitamin D. The length of this "vitamin D winter" depends
>on the latitude. In tropics you naturally get sufficient UVB-radiation
>throughout the year. See the studies by Webb et al. and Engelsen et al
>in the references later in this message
>
>>Also, what would a "sufficient number of sunny summer days" be?
>>
>It has been estimated that the bodies of healthy men use 3000 - 5000
>IU of vitamin D/d, if it is available. So to retain the vitamin D
>status (serum 25(OH)D concentration), one needs in average get that
>amount per day from whatever sources. Food is almost neglible source
>of vitamin D (fish is the best) and you cannot get 3000 - 5000/d from
>food. You can approximate the sufficient number of days, when you know
>that the maximum dose from exposure to the sun is 10 000 - 25 000 IU/d
>(you can use 10 000 in calculations), and that you need to get in
>average about 3000 - 5000 IU/d (say 4000 IU/d). Rough estimate is that
>you would need to get the maximum dose (20 minutes full body exposure,
>if you are white) every 2.5 days in the midday in a sunny summer day
>or more often, if you cannot do it in midday, time is shorter or you
>don't get full body exposure. This is for optimal vitamin D levels.
>Many people get less and are doing ok, but risk of some chronic
>diseases may increase if the average daily dose is much too low. And
>old people synthetize vitamin D in the skin much less effectively than
>young people, they may produce only 25% of the amount younger people
>can produce. Therefore older people may need supplements throughout
>the year.
>
>>And does the adequate supply then last through the fall, winter and spring?
>
>It depends on the latitude. In tropical areas cutaneous synthesis of
>vitamin D is possible throughout the year, but in far north and south
>there is no cutaneous synthesis during "vitamin D winter", whose
>length depends on the latitude. IMHO, in these areas it's sensible to
>supplement with art least 2000 IU/d during "vitamin D winter" to
>prevent vitamin D level falling too much in the winter (some vitamin D
>researcers thinj that big seasonal fluctuations in vitamin D level
>could be harmful). Again I would recommend that you browse through the
>studies by Webb et al. and Engelsen et al in the references later in
>this message
>
>
>You may find following references useful:
>
>Vieth R.
>Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and
>safety.
>Am J Clin Nutr. 1999 May;69(5):842-56. Review.
>PMID: 10232622 [PubMed - indexed for MEDLINE]
><http://www.ajcn.org/cgi/content/full/69/5/842>
>
>Vieth R, Chan PC, MacFarlane GD.
>Efficacy and safety of vitamin D3 intake exceeding the lowest observed
>adverse effect level.
>Am J Clin Nutr. 2001 Feb;73(2):288-94.
>PMID: 11157326 [PubMed - indexed for MEDLINE]
><http://www.ajcn.org/cgi/content/full/73/2/288>
>
>Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ.
>Human serum 25-hydroxycholecalciferol response to extended oral dosing
>with cholecalciferol.
>Am J Clin Nutr. 2003 Jan;77(1):204-10. Erratum in: Am J Clin Nutr.
>2003 Nov;78(5):1047.
>PMID: 12499343 [PubMed - indexed for MEDLINE]
><http://www.ajcn.org/cgi/content/full/77/1/204>
><http://www.ajcn.org/cgi/content/full/78/5/1047> (Erratum)
>
>Webb AR, Kline L, Holick MF.
>Influence of season and latitude on the cutaneous synthesis of vitamin
>D3: exposure to winter sunlight in Boston and Edmonton will not
>promote vitamin D3 synthesis in human skin.
>J Clin Endocrinol Metab. 1988 Aug;67(2):373-8.
>PMID: 2839537 [PubMed - indexed for MEDLINE]
><http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrie ve&dopt=abstractplus&list_uids=2839537>
>
>Engelsen O, Brustad M, Aksnes L, Lund E.
>Daily duration of vitamin D synthesis in human skin with relation to
>latitude, total ozone, altitude, ground cover, aerosols and cloud
>thickness.
>Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90.
>PMID: 16354110 [PubMed - indexed for MEDLINE]
><http://www.bioone.org/perlserv/?request=get-abstract&issn=0031-8655&volume=81&page=1287>
>
>Check out also the pages
>
>VitD Duration of Vitamin D Synthesis in Human Skin
><http://zardoz.nilu.no/~olaeng/fastrt/VitD.html>
>
>VitD-ez Easy Duration of Vitamin D Synthesis in Human Skin
><http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html>
>
>mentioned in the above abstract.
>
Some additional references:

Matsuoka LY, Wortsman J, Haddad JG, Hollis BW.
In vivo threshold for cutaneous synthesis of vitamin D3.
J Lab Clin Med. 1989 Sep;114(3):301-5.
PMID: 2549141 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlu s&list_uids=2549141>

Webb AR.
Who, what, where and when-influences on cutaneous vitamin D synthesis.
Prog Biophys Mol Biol. 2006 Sep;92(1):17-25. Review.
PMID: 16766240 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrie ve&dopt=abstractplus&list_uids=16766240>

Lucas RM, Ponsonby AL.
Ultraviolet radiation and health: friend and foe.
Med J Aust. 2002 Dec 2-16;177(11-12):594-8.
PMID: 12463975 [PubMed - indexed for MEDLINE]
<http://www.mja.com.au/public/issues/177_11_021202/luc10478_fm.html>


--
Matti Narkia

Matti Narkia wrote:
> >> >
>
> >"full body" exposure,
>
> Naked. I thought that that would be obvious. Close enough
> approximation is not too big swimming suit.
>
> >sunny or partly cloudy,
>
> I did write "sunny summer day". You get some reduced UVB-radiation
> even on partly cloudy summer day, but the maximum dose may be
> decreased or/and time needed for it may be lengthened.
>
> >morning or mid-day or afternoon,
>
> Midday for the maximum dose, although a reduced dose may be obtained
> in the morning and afternoon.
>

Matti,

Thanks for that explanation.

I have a couple more questions. It seems like I remember reading years
ago that, for maximum D, one should not bath immediately before or
after exposure. It seemed to have something to do with oil on the skin.
They said this oil needed to be re-absorbed into the skin after
exposure for the body to get the maximum effect. I have not seen this
anywhere since. Is this valid?

Also, what is your opinion regarding tanning beds? At least there is no
variation from day to day and season to season.

Thanks,

John

On 12 Oct 2006 08:45:37 -0700, "JohnHace" <johnh@amcoex.com> wrote:
>
>Matti Narkia wrote:
>> >> >
>>
>> >"full body" exposure,
>>
>> Naked. I thought that that would be obvious. Close enough
>> approximation is not too big swimming suit.
>>
>> >sunny or partly cloudy,
>>
>> I did write "sunny summer day". You get some reduced UVB-radiation
>> even on partly cloudy summer day, but the maximum dose may be
>> decreased or/and time needed for it may be lengthened.
>>
>> >morning or mid-day or afternoon,
>>
>> Midday for the maximum dose, although a reduced dose may be obtained
>> in the morning and afternoon.
>>
>
>Matti,
>
>Thanks for that explanation.
>
>I have a couple more questions. It seems like I remember reading years
>ago that, for maximum D, one should not bath immediately before or
>after exposure. It seemed to have something to do with oil on the skin.
>They said this oil needed to be re-absorbed into the skin after
>exposure for the body to get the maximum effect. I have not seen this
>anywhere since. Is this valid?
>
I've heard the same story, but I don't know if it is true. I think
that the logic behind the story is that vitamin D is formed so near
the surface of the skin, that having a shower or bath could wash it
away before it can be absorbed and moved to the circulation. So it all
comes down to the question whether vitamin D formed so near the skin
surface that it could be washed away? I honestly don't know.

>Also, what is your opinion regarding tanning beds? At least there is no
>variation from day to day and season to season.
>
If with tanning beds you mean regular solariums, they are no use in
getting vitamin D, because they produce only or mostly UVA radiation,
and not UVB-radiation needed to promote cutaneous vitamin D synthesis.
But there are other kind of "sun beds", which are designed to promote
vitamin D synthesis in the skin, and they produce also UVB radiation.
They are not yet as common as regular solariums, and I don't know
about their safety. But if proven safe, the advantage would of course
be that you could get the same constant vitamin D production in the
skin throughout the year, as you mentioned. Still, why to bother, when
you can take supplements, which cause nor harm for the skin, whenever
you don't get enough vitamin D from the sun.








--
Matti Narkia

Matti Narkia wrote:
> I.P. Freely wrote:
>
>> Matti Narkia wrote:
>>> Anything longer that 20 minutes is not necessary, and
>>> could be harmful.

>> But isn't the production of D self-limiting?
>
> That's exactly what I wrote, if you bother to read my message.

I "bothered", Matti, but interpreted your comment differently than you
intended.

> After
> 20 minutes in the sun as much vitamin D is destroyed in the skin by
> sunlight as is produced by the stimulation by the sun's UVB-radiation.
> Therefore for vitamin D production any longer stay in the sun than 20
> minutes at the time is useless, waste of time and may harm the skin.

Because you answered "Does the adequate supply then last through the
fall, winter and spring?" with "It depends on the latitude" and since
ANY sun "harms the skin", I presumed you meant longer exposure would
overdo the D in the long haul. Thanks for correcting my misinterpretation.

I.P.

On Thu, 12 Oct 2006 17:15:35 -0700, "I.P. Freely"
<fuhgheddaboutit@noway.nohow> wrote:

>Matti Narkia wrote:
>> I.P. Freely wrote:
>>
>>> Matti Narkia wrote:
>>>> Anything longer that 20 minutes is not necessary, and
>>>> could be harmful.
>
>>> But isn't the production of D self-limiting?
>>
>> That's exactly what I wrote, if you bother to read my message.
>
>I "bothered", Matti, but interpreted your comment differently than you
>intended.
>
Ok, no problem. Perhaps I should have expressed myself more clearly.

>> After
>> 20 minutes in the sun as much vitamin D is destroyed in the skin by
>> sunlight as is produced by the stimulation by the sun's UVB-radiation.
>> Therefore for vitamin D production any longer stay in the sun than 20
>> minutes at the time is useless, waste of time and may harm the skin.
>
>Because you answered "Does the adequate supply then last through the
>fall, winter and spring?" with "It depends on the latitude" and since
>ANY sun "harms the skin", I presumed you meant longer exposure would
>overdo the D in the long haul. Thanks for correcting my misinterpretation.
>
Thanks for staying interested.


--
Matti Narkia

Matti Narkia wrote:
> Thanks for staying interested.

It's pretty easy, given D's critical role in many bodily systems,
functions, and maladies. I've been watching it for many years, having
lived many places from Florida to near Canada.

I.P.