Limited sun exposure as an alternative/primary form of vitamin D suppl

Per title. An impassioned discussion regarding this topic started in Zoolander's regimen thread, and I'm hoping to move it here.

What's been said so far:

http://www.imminst.o...o...1030&st=120

As food for further discussion, this 73 page Nov. 2005 report of a meeting in London at the House of Commons, chaired by Ian Gibson MP, examines the evidence for the D-deficiency epidemic and considers how policy on fortification
of food, sunbathing, and use of supplements might be changed to provide more
vitamin D and better protection against chronic disease in the 21st century:

"Sunlight, Vitamin D, and Health"

http://www.healthres...rts/sunbook.pdf

Includes participation by some of the world's leading experts in the field, including Vieth (whose seminal 1999 study was cited several times in Zoolander's thread) and Holick, who determined the mechanism for how vitamin D is synthesised
in the skin and demonstrated the effects of ageing, obesity, latitude, seasonal change, sunscreen use, skin
pigmentation and clothing on this vital cutaneous process. Credentials of all participants are included at the end of the report.

Edited by TianZi, 28 April 2008 - 08:43 AM.

In Holick's pop-sci book, he advocates sun exposure due to what he calls photo-isomers and the serotonin factor that would not be present otherwise. But, he also advocated eating Vitamin D-rich foods or supplementation for those who would need to limit sun exposure.

You've got it exactly backwards: What's been discredited is the idea that limited unprotected sun exposure isn't an optimal form of vitamin D supplementation. Even the National Institute of Health, an organization that's quite conservative, now recommends responsible, limited unprotected sun exposure as a form of vitamin D supplementation, a very recent change in position.

Only because it would kill them to recommend supplements.

Holick was quite appropriately booted out of the dermatology department of the Boston University School of Medicine for recommending getting D from sunlight.

As regards the South India study, cite any other performed anywhere else in the world that came to the same conclusion.

If you think anecdotal accounts on a random website carry the same weight as studies published in journals

They don't. I would think long and hard before doing something based on an anecdote, but I would readily not do something based on an anecdote. I'm not going to wait for a proper study to come out in order for me to take appropriate precautions. Prudence dictates that you accept the possibility that sunlight can create too much vitamin D in some people. I agree that there is a feedback mechanism that limits vitamin D production, but clearly some people have enhanced 25-hydroxylation ability that could result in toxicity. It may be a small risk, but it is so easy to get around that it's foolish to stick your head in the sand and say "Only one peer reviewed study! It doesn't count! Anecdotes don't count! La la la I can't hear you."

As evidenced by studies cited in this very thread, there may very well be significant differences between endogenous and exogenous supplementation of vitamin D3, besides an internal control mechanism for one and not the other, for reasons we don't yet fully understand.

There is zero evidence of toxicity from supplements in people who keep their blood levels in the recommended range. I find it hard to understand how someone can poo poo my concerns about blindly getting 10,000 IU of vitamin D when I have three peer reviewed journal articles (The Indian study, the study used to set the UL (PMID: 6746514), and PMID: 9245225.), and multiple anecdotes as support, while insisting without a shred of evidence that titrated vitamin D supplementation is more dangerous than sunbathing.

Bottom line: Supplementation coupled with blood testing is cheap, safe, effective, and convenient. Sunbathing is time-consuming, unreliable, and introduces unnecessary risks. I encourage you to read all of Fredrik's posts in the skin care section. Here's an excerpt of one.

Well, the whole story of skin aging is daily photoprotection. At least 80% of skin aging is caused by incidental exposure to daylight. 5-15 minutes of UV every other day will raise your skin levels of skin degrading/remodeling enzymes, collagenase and elastase for over a week until they return to normal. When subjects (office workers) wore UV-dosimeters they averaged 18 hours of sun exposure a week. So even if you practice sun avoidance, which is the first and most important thing to do, you still need a daily sunscreen.

1. In view of Holick's credentials--among other things, the man discovered the mechanism by which vitamin D is synthesized in the body--it doesn't seem fair to dismissively categorize his book as "pop sci". Regardless of how controversial his conclusions may be in certain circles in the US, who, Shepard, do you believe would be better qualified to write a book on this topic?

I wish I had handy a copy of his book. To my knowledge, there is a section in it detailing why he believes limited sun exposure, conditions and circumstances permitting, is superior to ingesting supplements for achieving optimal vitamin D levels. Shepard seems to have touched on that in his post, but without enough detail to make the rationale intelligible to me.

2. Holick has been censured by the US dermatological association. However, his essential views have been embraced by the health authorities in many other first world nations, including Australia & New Zealand (per the paper linked at the beginning of this thread), many nations in northern europe, and even the country of my residence, Taiwan. The US dermatological association's stance is increasingly isolated at the global level. The US NIH is clearly moving away from the US dermatological association's draconian viewpoint regarding sun exposure, as shown in my other posts, and key individuals in the American Cancer Society have said they are very close to recommending limited regular unprotected exposure to sunlight in view of its almost certain role in drastically lowering incidence and mortality rates for most forms of cancer.

3. As far as maximum safe daily exogenous vitamin D consumption, the numbers seem to be all over the place. Plenty of experts claim the average person should consume at least 10,000 IU daily, with research supporting this. Others put the number far lower.

But apart from perhaps the authors of the South India study, no experts seem concerned that endogenous production of vitamin D in and of itself can reach dangerous levels. The "dissenting opinions" in the UK paper linked in the OP do not mention as a reason for avoiding sun exposure the possibility of toxic or otherwise dangerous levels of vitamin D levels resulting therefrom--rather, they are concerned about increased risk of incidence of skin cancer. Krillin's concern about potential vitamin D toxicity resulting from overexposure to sunlight seems very much a fringe notion. It doesn't have broad, or even narrow, support within the scientific community.

4. What's interesting is that a broad swath of the scientific community is concerned about the potential for exogenous vitamin D supplementation to reach toxic levels with less than 10,000 IU's consumed daily, but they apparently aren't concerned about the potential for endogenous production of vitamin D to reach toxic levels, even though the equilibrium point is about the equivalent of 10,000 IU's daily!

This tells me current research is pointing to some qualitative difference between the two we don't yet fully understand. If the vitamin D3 produced endogenously is indeed identical to the vitamin d3 consumed exogenously, why does the body recognize and regulate levels of the one, but not the other?

Krillin, I'd be obliged if you would take up the gauntlet and find a researcher who attempts to answer this question. I haven't found one. Vieth's study seems to have been a watershed in this area, and he described in detail how the self-regulating mechanism works as regards endogenous vitamin d3 production, but I didn't see an explanation from him as to why the body regulates one form of vitamin d3 but not another. My guess is that he doesn't know, unless I've missed something, which is entirely possible.

5. Finally as regards that South India study: This study doesn't even suggest that vitamin d3 levels can become broadly "toxic" with sufficient exposure to the sun; rather it concludes a specific cardivascular ailment may be associated with sun exposure.

The problems with this study, in my opinion, are manifold at least for now:

a. It stands alone in its conclusions;

b. Its conclusions contradict, or at least are in tension with, those in a great number of other studies showing cardiovascular benefits from increased levels of sun exposure (e.g., the UK gardener study) or from exogenous consumption of vitamin d (e.g., the Harvard study);

c. The ailment in question was found primarily among the poor and not the wealthy, and we are talking "India poor" here--complete, utter, abject povery unseen in 1st World nations. The fact the poor in this study had higher vitamin d3 levels due to increased sun exposure may be a "red herring"; what was in the water that those people were drinking, etc.; and

d. We are talking South India, home of the caste system, untouchables included. I can't imagine a much more inbred, less representative population sample to draw broad conclusions from.

6. As far as aging of the skin caused by suinlight goes, I believe most studies have found a significant risk for this only if the skin burns, or at least is exposed unprotected for very long periods of time (2 or more hours on a regular basis). I don't think any study has conclusively shown that exposure without burning, or for less than 1 hour daily, significantly enhances aging of the skin. I believe experts have speculated this may be so, but without conclusive evidence. (If I'm wrong about this, please point me to the appropriate studies.)

Regardless, it's cosmetic. There's an "unholy bargain" a lot of us knowingly strike with a lot of the supplements we take, or things we do to try to stay healthy as long as possible. Often bad comes with the good, and there is an inevitable trade-off that's made. Ex.: I take DHEA. I'm aware of the potential, very slim prostate cancer risk. I still believe the benefits of taking it outweigh the risks.

Edited by TianZi, 29 April 2008 - 03:38 PM.

1. In view of Holick's credentials--among other things, the man discovered the mechanism by which vitamin D is synthesized in the body--it doesn't seem fair to dismissively categorize his book as "pop sci". Regardless of how controversial his conclusions may be in certain circles in the US, who, Shepard, do you believe would be better qualified to write a book on this topic?

I don't have anything against Holick. His main book is a pop-sci book. Just as any other you'll find in a regular bookstore. They're dumbed down to appeal to a larger audience. He has others, but I've not read them.

I wish I had handy a copy of his book. To my knowledge, there is a section in it detailing why he believes limited sun exposure, conditions and circumstances permitting, is superior to ingesting supplements for achieving optimal vitamin D levels. Shepard seems to have touched on that in his post, but without enough detail to make the rationale intelligible to me.

There isn't any detail in the book, either. I said "what he calls photo-isomers", because that's as in-depth as he goes. It's a one-page mention that isn't even in the regular text. And, the serotonin for mood boosting, but that's easily enough understood. Longer duration UV-light = higher serotonin turnover. Better mood.

3. As far as maximum safe daily exogenous vitamin D consumption, the numbers seem to be all over the place. Plenty of experts claim the average person should consume at least 10,000 IU daily, with research supporting this. Others put the number far lower.

But apart from perhaps the authors of the South India study, no experts seem concerned that endogenous production of vitamin D in and of itself can reach dangerous levels. The "dissenting opinions" in the UK paper linked in the OP do not mention as a reason for avoiding sun exposure the possibility of toxic or otherwise dangerous levels of vitamin D levels resulting therefrom--rather, they are concerned about increased risk of incidence of skin cancer. Krillin's concern about potential vitamin D toxicity resulting from overexposure to sunlight seems very much a fringe notion. It doesn't have broad, or even narrow, support within the scientific community.

4. What's interesting is that a broad swath of the scientific community is concerned about the potential for exogenous vitamin D supplementation to reach toxic levels with less than 10,000 IU's consumed daily, but they apparently aren't concerned about the potential for endogenous production of vitamin D to reach toxic levels, even though the equilibrium point is about the equivalent of 10,000 IU's daily!

Please, can't we get away from the notion of the average person? Vitamin D should be approached as a hormone, not a vitamin. The required dose for one individual can be toxic for another. Look at this Vieth paper. In figure 1's middle graph, he gets it right: we have overlapping deficiency and toxicity zones. But that freaks him out so he uses wishful thinking to redraw the graph to have separate deficiency and toxicity zones. It's understandable: more people would be helped than harmed by raising the RDA and UL. But I'm one of the ones who would be harmed. 1000 IU brings me to 45.1 ng/ml. Most papers show a linear relationship between intake and blood levels. I'd be screwed if I listened to him.

A more cunning response to my concern would have been to say, "Thanks for the heads up Krillin. But I test my blood level of vitamin D to make sure I'm getting enough sun, so there's no chance of my getting an overdose."

If the vitamin D3 produced endogenously is indeed identical to the vitamin d3 consumed exogenously, why does the body recognize and regulate levels of the one, but not the other?

Unmetabolized (inactive) vitamin D production is what is regulated in the skin during sunbathing. Then it gets hydroxylated to 25-D. There is little feedback control here. From what I've read, 25-hydroxylation is only inhibited by really high vitamin D activity from both 25-D and 1,25-D. That's how the Marshall Protocol people can have high 1,25 D and low 25-D. Hydroxylation to 1,25 D is tightly controlled by blood calcium level through PTH, unless you're like the Marshall Protocol people who have macrophages going crazy with the 1-hydroxylation.

Thus, the control mechanism is too far upstream for it to work with ingested vitamin D.

6. As far as aging of the skin caused by suinlight goes, I believe most studies have found a significant risk for this only if the skin burns, or at least is exposed unprotected for very long periods of time (2 or more hours on a regular basis). I don't think any study has conclusively shown that exposure without burning, or for less than 1 hour daily, significantly enhances aging of the skin. I believe experts have speculated this may be so, but without conclusive evidence. (If I'm wrong about this, please point me to the appropriate studies.)

Regardless, it's cosmetic. There's an "unholy bargain" a lot of us knowingly strike with a lot of the supplements we take, or things we do to try to stay healthy as long as possible. Often bad comes with the good, and there is an inevitable trade-off that's made. Ex.: I take DHEA. I'm aware of the potential, very slim prostate cancer risk. I still believe the benefits of taking it outweigh the risks.

You're just embarrassing yourself here. The inflammatory response begins in a matter of minutes. Ignore inflammation at your peril. Read some articles like these. (erythema = sunburn)

Nature. 1996 Jan 25;379(6563):335-9.
Molecular basis of sun-induced premature skin ageing and retinoid antagonism.
Fisher GJ, Datta SC, Talwar HS, Wang ZQ, Varani J, Kang S, Voorhees JJ.
Department of Dermatology, University of Michigan Medical School, Ann Arbor 48109-0528, USA.

Damage to skin collagen and elastin (extracellular matrix) is the hallmark of long-term exposure to solar ultraviolet irradiation, and is believed to be responsible for the wrinkled appearance of sun-exposed skin. We report here that matrix-degrading metalloproteinase messenger RNAs, proteins and activities are induced in human skin in vivo within hours of exposure to ultraviolet-B irradiation (UVB). Induction of metalloproteinase proteins and activities occurred at UVB doses well below those that cause skin reddening. Within minutes, low-dose UVB upregulated the transcription factors AP-1 and NF-kappa B, which are known to be stimulators of metalloproteinase genes. All-trans retinoic acid, which transrepresses AP-1 (ref. 8), applied before irradiation with UVB, substantially reduced AP-1 and metalloproteinase induction. We propose that elevated metalloproteinases, resulting from activation of AP-1 and NF-kappa B by low-dose solar irradiation, degrade collagen and elastin in skin. Such damage, if imperfectly repaired, would result in solar scars, which through accumulation from a lifetime of repeated low-dose sunlight exposure could cause premature skin ageing (photoageing).

PMID: 8552187

Acta Dermatovenerol Croat. 2003;11(3):158-62.
Sunscreens--the ultimate cosmetic.
Wolf R, Matz H, Orion E, Lipozencić J.
Dermatology Unit, Kaplan Medical Center, 76100 Rechovot, Israel. wolf_r@netvision.net.il

One decade ago, a sun protection factor (SPF) of 15 was considered a complete blocker of ultraviolet radiation (UV). The logic behind that cutoff point was that sunscreens with this SPF number would always prevent erythema and that preventing erythema would prevent all the ill effects of UV exposure. Today, we know that both of these assumptions were wrong and we tend to recommend higher SPF. Consumers apply only about one-quarter to one-half thickness of the layer of sunscreen material used to measure the SPF in the laboratory. That means that less than 50% of the SPF number claimed on the label is spread on the consumer's skin, meaning that a sunscreen with an SPF 30 will give the real protection of an SPF of 15. Therefore, recommend 60 when you want a real protection of 30! Significant injury, DNA damage, mutations, and carcinogenesis can and do occur also with cumulative suberythemal UV exposure. Thus, erythema induction, a criterion that defines SPF, is not a good indicator of UV damage. We also need higher SPF values to prevent the damage caused by suberythemal doses of UV. The value of the SPF claimed on the label is diminished by environmental factors that are not taken into account during SPF measurements in the laboratory, such as sweating, water immersion, rubbing off, and photodegradation. There are some misunderstandings and confusion about the mode of action of physical sunscreens. It was originally considered that, in contrast to organic sunscreens, the inorganic metal oxides (zinc oxide and titanium dioxide) acted as scatterers or reflectors of UV light, as a mirror. This is not the case with modern micronized forms of metal oxides. It has been shown that both zinc oxide and titanium dioxide mobilize electrons within their atomic structure while absorbing UV radiation. Thus, although metallic oxides are not inert per se, in their coated form they are stable, non-toxic, and safe and they act as highly efficient UV attenuators. Therefore, we recommend our patients to use this type of sunscreens. We should exert all our influence upon our patients not to expose themselves to excessive sunlight, to routinely use generous layers of sunscreen agents, and to wear protective clothing. To wait for the dust to settle around the issue of the effectiveness of sunscreens in preventing melanoma, while the ideal sunscreens--topical, systemic, whatever--are at our disposal, is a luxury we cannot afford.

PMID: 12967508

1. In view of Holick's credentials--among other things, the man discovered the mechanism by which vitamin D is synthesized in the body--it doesn't seem fair to dismissively categorize his book as "pop sci". Regardless of how controversial his conclusions may be in certain circles in the US, who, Shepard, do you believe would be better qualified to write a book on this topic?

I don't have anything against Holick. His main book is a pop-sci book. Just as any other you'll find in a regular bookstore. They're dumbed down to appeal to a larger audience. He has others, but I've not read them.

I wish I had handy a copy of his book. To my knowledge, there is a section in it detailing why he believes limited sun exposure, conditions and circumstances permitting, is superior to ingesting supplements for achieving optimal vitamin D levels. Shepard seems to have touched on that in his post, but without enough detail to make the rationale intelligible to me.

There isn't any detail in the book, either. I said "what he calls photo-isomers", because that's as in-depth as he goes. It's a one-page mention that isn't even in the regular text. And, the serotonin for mood boosting, but that's easily enough understood. Longer duration UV-light = higher serotonin turnover. Better mood.

Shepard,

I see, thanks.

Krillin, perhaps you should get more sunlight. As Shepard points out, it may improve mood, and you seem to have a problem with your temper. I do appreciate the studies you've linked, but you could have done so without the insulting comments, which seem a trademark feature of your posts on these boards.

Edited by TianZi, 30 April 2008 - 08:07 AM.

I was interested to see what the Australia and New Zealand health authorities had to say about sun exposure, since that position has recently changed, per the UK paper linked at the top of the page.

I found this,dated 15 March 2007:

"AUSTRALIAN AND NEW ZEALAND BONE AND MINERAL SOCIETY,
OSTEOPOROSIS AUSTRALIA, THE AUSTRALASIAN COLLEGE OF DERMATOLOGISTS
AND THE CANCER COUNCIL AUSTRALIA

RISKS AND BENEFITS OF SUN EXPOSURE
POSITION STATEMENT"

Here's the link:

http://www.osteoporo...ure_OA_2007.pdf


The following quoted paragraph from pages 3 to 4 is thought provoking:

"Recently, some studies have been published that suggest possible beneficial effects of
sun exposure in the prevention or improvement in outcome of treatment for a
number of other diseases including breast, prostate, and colorectal cancer, non-
Hodgkin lymphoma, diabetes and multiple sclerosis7,16,17,18,19,20,21. The biological
pathways underlying these observed associations are not clear. While vitamin D is
likely to be a contributing factor to disease risk reduction, it is not yet clearly known
whether there are factors other than vitamin D that is derived from sun exposure that
may play a role. There is insufficient evidence to assume that vitamin D supplementation and sun exposure are equivalent in their beneficial effects. Therefore at this stage, there is insufficient evidence for any definitive action to be taken on these findings or any recommendations to be made, as more research is needed."

Persons living in southern Australia are recommended to get 2 to 3 hours of unprotected sun exposure during the winter each week, unless they have special health concerns which make that amount of sunlight risky for them. People are recommended to avoid sun exposure when the UV Index is 3 or higher (i.e., 1-3). Page 2.

which seem a trademark feature of your posts on these boards.

im actually insulted by that. krillin is what i would consider one of the higher level contributers to the health & nutrition subforums, and i have not once seen him be 'nasty' to anyone in all the years ive been here.

which seem a trademark feature of your posts on these boards.

im actually insulted by that. krillin is what i would consider one of the higher level contributers to the health & nutrition subforums, and i have not once seen him be 'nasty' to anyone in all the years ive been here.

Look at the NSCA thread. Apparently I'm a racist.

Look at the NSCA thread. Apparently I'm a racist.

well we all knew that already lol

which seem a trademark feature of your posts on these boards.

im actually insulted by that. krillin is what i would consider one of the higher level contributers to the health & nutrition subforums, and i have not once seen him be 'nasty' to anyone in all the years ive been here.

Look at the NSCA thread. Apparently I'm a racist.

Shephard,

I neither stated nor implied any such thing. What I did do was question whether the term "bro-logic" as used by you had racist overtones, and criticize your use of that term in a contemptuous manner to dismiss arguments fielded by bodybuilders (and most fitness professionals, regarding multiangle exercise regimens targeting a specific muscle) as reasoning employed by people who'd "never cracked a textbook". There is a crucial difference between criticizing specific (mis)statements, and making an ad hominem attack on a person generally. Many persons who are not racists nonetheless make isolated racially derogatory remarks, or sweeping overgeneralizations likely to offend, from time to time. It's a function being an imperfect human being.

As regards Krillin, I don't question the value of his contributions to this forum. It is my perception, from having read some of his posts, that he frequently includes unnecessary snarky asides likely to offend, such as by saying to me "You're just embarrassing yourself now" when in the section of my prior post to which he responded I had in fact requested correction if my limited understanding of the subject was incorrect.

Edited by TianZi, 01 May 2008 - 08:45 AM.

Many persons who are not racists nonetheless make isolated racially derogatory remarks, or sweeping overgeneralizations likely to offend, from time to time. It's a function being an imperfect human being.

use this gif from now on when that happens:

As regards Krillin, I don't question the value of his contributions to this forum. It is my perception, from having read some of his posts, that he frequently includes unnecessary snarky asides likely to offend, such as by saying to me "You're just embarrassing yourself now" when in the section of my prior post to which he responded I had in fact requested correction if my limited understanding of the subject was incorrect.

theres a big difference between making a snarky comment and being nasty.

i know im in the middle of finals week, and id imagine krillin & shep are coming up on or in the midst of them as well. had i gotten into that type of debate on here this week i may have put a knife into my laptop, so a few extra snarky comments are most likely the result of a little stress we're a pretty nice crew in general

also i will now be using the word snarky as much as possible :D

Shephard,

I neither stated nor implied any such thing.

I know you didn't say that. These are my jokes, people.

As regards Krillin, I don't question the value of his contributions to this forum. It is my perception, from having read some of his posts, that he frequently includes unnecessary snarky asides likely to offend, such as by saying to me "You're just embarrassing yourself now" when in the section of my prior post to which he responded I had in fact requested correction if my limited understanding of the subject was incorrect.

No whining allowed. We Kurzweil-skeptics didn't when you called us "internet MD's". And who wouldn't have been embarrassed to have written that passage? You don't just casually blow off one of Fredrik's statements without trying to research it.

As regards Krillin, I don't question the value of his contributions to this forum. It is my perception, from having read some of his posts, that he frequently includes unnecessary snarky asides likely to offend, such as by saying to me "You're just embarrassing yourself now" when in the section of my prior post to which he responded I had in fact requested correction if my limited understanding of the subject was incorrect.

No whining allowed. We Kurzweil-skeptics didn't when you called us "internet MD's". And who wouldn't have been embarrassed to have written that passage? You don't just casually blow off one of Fredrik's statements without trying to research it.

I know this is a bump but it's a worthy one because this is an interesting topic.

Krillin, I'm fully with Tianzi here. Your immaturity in your posts makes it very difficult for me not to come to the following conclusions (keep in mind I am trying hard):
***

I'm trying. I really am. My advice (which considering 1 and 2 you are likely to ignore) is to try and remove the emotional aspect from your posts. Remember dude no one is attacking you, they're attacking your argument. Don't be hurt.
***

That taken care of I'd like to know if anyone else here has anymore info. on this. Especially the advice of dermatologists etc in Australia.

(edited by Matthias: no oil into the fire, please)

Edited by Matthias, 25 May 2008 - 10:14 PM.

We could all together stop the ad hominem or any kind of insults, then everyone will be happy =)
Though, who cares if someone is arrogant or not if his contributions are outstanding...

TianZi, I wonder whether you agree that one at least wants to protect the face at all costs, but may want to expose other not so crucial parts of the body?
Assuming both of you are right to some extent (personally I don't know), TianZi, one could also cycle body parts, which are exposed to sun, to prevent more UV damage, but also get most sun benefits, no?

TianZi, I wonder whether you agree that one at least wants to protect the face at all costs, but may want to expose other not so crucial parts of the body?
Assuming both of you are right to some extent (personally I don't know), TianZi, one could also cycle body parts, which are exposed to sun, to prevent more UV damage, but also get most sun benefits, no?

Excellent point. I'd really like to know what people have to say on that.

I found this article:

AUSTRALIAN AND NEW ZEALAND BONE AND MINERAL SOCIETY,
OSTEOPOROSIS AUSTRALIA, THE AUSTRALASIAN COLLEGE OF DERMATOLOGISTS
AND THE CANCER COUNCIL AUSTRALIA (sorry for caps it's a copy and paste)

http://www.cancer.or...sure03May07.pdf

For most people, sun protection to prevent skin cancer is required when the
UV index is moderate or above (i.e. UV index is 3 or higher). At such times
sensible sun protection behaviour is warranted and is unlikely to put people at
risk of vitamin D deficiency.

In winter, in the southern regions of Australia where UV radiation levels are less intense, maintenance of vitamin D levels may require 2-3 hours of sunlight exposure to the face, arms and hands or equivalent area of skin over a week.

Basically from the latter parts of Autumn to the near-end of spring the UV index hovers around 0-3 for southern Australians.

According to this statement you should "expose your face, hands and arms or equivalent area of skin". So I guess don't expose your face but keep your hands, arms and some other part of your body exposed for 25 minutes during the day (around 12pm-1pm is best). This figure would be higher depending on how dark your skin is.

Hmm. 25 minutes from 12pm-1pm in the height of winter with my arms, hands and legs exposed. I don't see how that's going to be possible without freezing to death.

Another ponderable is that if you are protecting your skin from UV light during winter with a sunscreen yet exposing these other parts of your body you will have a weird uneven tan. White face, dark arms, hands, legs.

For those not from Australia, everything I have written here I think would be magnified for those not living down under. To my knowledge the UV is very high here compared to most other parts of the world (hole in ozone layer). So if you're wearing sunscreen in Europe during winter you are probably getting zero vitamin D.

Edited by Ben - Aus, 25 May 2008 - 12:24 PM.

Most papers show a linear relationship between intake and blood levels.

Found something kewl. The serum 25-D/serum D relationship is linear up until you get to the optimal 25-D range of 40-50 ng/ml. Then the slope starts to flatten. But the individual variation between D intake and serum D is even worse than I thought. 6400 IU gave people <1 – 75 ng/ml D and 12 – 77 ng/ml 25-D.

Thus, to my surprise it appears that 25-hydroxylation is roughly the same for everyone. The variable response to D supplements must be due to differing rates of liver clearance of vitamin D. (Certain drugs can induce the responsible enzymes.) One could also argue variable intestinal absorption efficiency, but the study found just as large a variation in the response to sunlight. Three or more hours of Hawaiian sun per day on five or more days per week for at least the preceding three months yielded <1 – 64 ng/ml D and 11 – 71 ng/ml 25-D.

Most papers show a linear relationship between intake and blood levels.

Found something kewl. The serum 25-D/serum D relationship is linear up until you get to the optimal 25-D range of 40-50 ng/ml. Then the slope starts to flatten. But the individual variation between D intake and serum D is even worse than I thought. 6400 IU gave people <1 – 75 ng/ml D and 12 – 77 ng/ml 25-D.

Thus, to my surprise it appears that 25-hydroxylation is roughly the same for everyone. The variable response to D supplements must be due to differing rates of liver clearance of vitamin D. (Certain drugs can induce the responsible enzymes.) One could also argue variable intestinal absorption efficiency, but the study found just as large a variation in the response to sunlight. Three or more hours of Hawaiian sun per day on five or more days per week for at least the preceding three months yielded <1 – 64 ng/ml D and 11 – 71 ng/ml 25-D.

This is an interesting result. It's indirect evidence that fairly large doses of D3 are reasonable for most people, unless circulating D3 has some negative effect. I was struck by the large individual variation also. In the supplemented people, they were using D3 tablets as opposed to gelcaps, so the absorption may have depended a lot on the amount of lipid in the person's diet. An awful lot of the sun-exposed people had pretty low circulating D3. This tells me that if even people who are supposedly spending a lot of time in the sun aren't getting enough D3, maybe sun exposure just isn't the best answer. As far as I'm concerned, I think that we have a good understanding of vitamin D biochemistry and supplementing is a good choice. The thing I'm concerned about is what important photosynthetic factors we have not discovered yet. Thus I can see getting some sun exposure as a reasonable thing to do. I don't want to expose my hands, face, or neck, since they have already been damaged enough. This makes sunbathing a little complicated, but whatever. It would sure be cool if there was an easy way to get UVB without UVA. I've heard vague claims that some sunbeds have UVA filters.

btw, krillin, thanks for posting this. The quality of this forum would go down a lot without you.

Edited by niner, 27 May 2008 - 03:51 AM.

Thus, to my surprise it appears that 25-hydroxylation is roughly the same for everyone. The variable response to D supplements must be due to differing rates of liver clearance of vitamin D. (Certain drugs can induce the responsible enzymes.)

Liver enzymes probably aren't as important as the rate of unmetabolized excretion.

http://www.direct-ms.....HAPTER 61.pdf

Since the increment in plasma 25(OH)D concentration per mcg dose is at least four times higher for 25(OH)D administration than for vitamin D3 administration, we can conclude that less than 25 percent of vitamin D molecules ever become 25(OH)D. At least three quarters of the molecules of vitamin D that enter the body are removed by some other fate.

Most vitamin D entering the circulation appears to be excreted unmetabolized into the bile.

It would sure be cool if there was an easy way to get UVB without UVA. I've heard vague claims that some sunbeds have UVA filters.

One drawback is that you lose the limitation on how much vitamin D gets produced. This article says that preD3 absorbs at wavelengths up to 325 nm, while 7-dehydrocholesterol only absorbs at up to 315 nm. Abstract Below.

Science, Vol 216, Issue 4549, 1001-1003
Copyright © 1982 by American Association for the Advancement of Science
Spectral character of sunlight modulates photosynthesis of previtamin D3 and its photoisomers in human skin
JA MacLaughlin, RR Anderson, and MF Holick

The photosynthesis of previtamin D3 from 7-dehydrocholesterol in human skin was determined after exposure to narrow-band radiation or simulated solar radiation. The optimum wavelengths for the production of previtamin D3 were determined to be between 295 and 300 nanometers. When human skin was exposed to 295-nanometer radiation, up to 65 percent of the original 7-dehydrocholesterol content was converted to previtamin D3. In comparison, when adjacent skin was exposed to simulated solar radiation, the maximum formation of previtamin D3 was about 20 percent. Major differences in the formation of lumisterol3, and tachysterol3 from previtamin D3 were also observed. It is concluded that the spectral character of natural sunlight has a profound effect on the photochemistry of 7-dehydrocholesterol in human skin.

There is insufficient evidence to assume that vitamin D supplementation and sun exposure are equivalent in their beneficial effects.

This is exactly what I've always wondered. Why do we equate these two things? It seems like an aprior assumption, at least in the popular literature on the subject. The relationship between human body and sunlight may be far, far more complex than we currently know, right?

Are people generally happier in sunny countries since they get more serotonine ?

I've heard that you need to live under about the 35th parallel to get enough Vitamin D all year round,is it any truth to this?

I live at the 63th parallel,do I get enough vitamin D during sunny days in the summer when the UV Index peaks at about 5-6?

Here's the funniest argument I've found for sun over supplements:

http://www.medscape....warticle/537784

"The literature is clear. Adequate amounts of vitamin D cannot be achieved at the current low levels set years ago by the Institute of Medicine—200 IU a day," Holick says. "Consumers should routinely be taking 5 times that amount, 1000 IU a day of vitamin D. It is misleading to suggest that nutritional supplementation is the answer. It is not practical to get our daily 1000 IU of vitamin D from popping a pill."

A tiny two cent pill is impractical? That guy really is in the pocket of the tanning industry.

There is insufficient evidence to assume that vitamin D supplementation and sun exposure are equivalent in their beneficial effects.

This is exactly what I've always wondered. Why do we equate these two things? It seems like an aprior assumption, at least in the popular literature on the subject. The relationship between human body and sunlight may be far, far more complex than we currently know, right?

That's entirely possible. But we do understand vitamin D, and we can take care of that via supplementation. If there's something else vital to health that is made photosynthetically... we don't yet know what it is. If people avoid sun but supplement D and are just as healthy as people who get sun, which is the case as far as I know, then we have some evidence for a lack of other important photosynthetic compounds. I'll tell you what I do know: The names of three people who have had melanoma. And two of them died from it.

This is a quandry of mine recently. I have been taking between 4K and 6K IU's/day of Vit D and my levels are OK (42 taken in Jan). With Vit D3 supplementation I feel like I can get consistent results. Now that it is approaching summer and I am getting more sun exposure my thoughts are I probably could/should scale back on the supplemental route. So last weekend I'mout in the sun for maybe 12 hours in 2 days. But I used sunscreen to avoid burn. Instead of taking 4-6K IU's I scaled back to 1K IU for those two days, but I'm left wondering how much D3 I got having worn sunscreen the whole time. Guess my point is the sun form seems less consistent to me.

the result of only ONE HOUR out in the sun (on a uv ray scale 9 day)

Edited by ajnast4r, 03 June 2008 - 12:41 AM.

the result of only ONE HOUR out in the sun (on a uv ray scale 9 day)

It gets to UV 14 here in the summer. E: I also wonder what Queensland would do to your skin hahah.

Edited by Ben - Aus, 06 June 2008 - 09:53 AM.