Sun light vs. damage & Vit.D

[Kasper]

The study about lifeguards in Israel (average 148 nmol/L) is particularly interesting.

I agree.
They seem to have a lot more kidney stones than normal... Shabtai M et al
"Eleven of 45 (24%) Lifeguards had proven N (= nephrolithiasis = kidney stones). This is approximately twenty times the incidence of N in the general population". Better OS et al

I haven't studied it. But it's interesting.
I don't understand why other sources don't warn for this risk.
Could it be that lower calcium intakes would give you less of a risk for kidney stones with high vitamin D levels ?

But I really don't have the time to take a good look at all those studies you posted at the moment.
But it is surely some material to consider.

[RRM]

Could it be that lower calcium intakes would give you less of a risk for kidney stones with high vitamin D levels ?

Correct.
The problem is however that vitamin D facilitates the uptake of calcium.
And, of course, there are great individual differences.
Evolutionary, whites have adapted to both high vitamin D levels and high Calcium intakes
by a decrease in the basic 'vitamin D-independent calcium absorption rates'.

[dime]

Could it be that lower calcium intakes would give you less of a risk for kidney stones with high vitamin D levels ?

My understanding was that vitamin D will mobilize calcium from the body stores in that case?

[RRM]

Could it be that lower calcium intakes would give you less of a risk for kidney stones with high vitamin D levels ?

My understanding was that vitamin D will mobilize calcium from the body stores in that case?

There is always calcium storing and remobilisation going on, 24/7.
The more calcium is absorbed, the higher those rates. (more absorption, more excretion)
Only if calcium intakes do not match calcium requirements (or in space), per saldo more bone will be remobilized than stored.

[RRM]

I conclude that the RDA is not adequate.

Suppose that you are right, and the Institute of Medicine is wrong,
then the desired serum 25(OH)D levels could be established by looking at sunlight exposure, right?

How to get natural vitamin D blood levels ?
The concentration of previtamin D in the skin reaches an equilibrium in white skin within 20 min of ultraviolet exposure.
Although it can take 3–6 times longer for pigmented skin to reach the equilibrium concentration of dermal previtamin D.

So, when we daily expose a group of white people to 20 minutes of sunlight exposure in a tropical country,
and then look at the resulting serum 25(OH)D concentrations, then we know how much 25(OH)D our blood needs to contain, right?
And for pigmented people that should be up to about 2 hours, right?
But lets make it 3 hours daily, or 4.
No, lets make it 5 hours daily, so that there can be no discussion whether its sufficient.
And lets do it in India, a sunny country.

Presence of 25(OH) D deficiency in a rural North Indian village despite abundant sunshine.
"The mean 25(OH)D values of all subjects in the rural area was 36.4 nmol / L....
even with five hours of daily sunshine exposure only 31.5% had serum 25(OH)D levels > or = 50 nmol/L."

So, from this study we can conclude that a level of 36.4 nmol of 25(OH)D is a safe level,
Right?

[Kasper]

So, from this study we can conclude that a level of 36.4 nmol of 25(OH)D is a safe level,Right?

Depens on how much clothes they were wearing.

Those 20 min. for white people, and 2 hours of pigmented people, is measured for whole body UVB exposure. After that time, the skin reaches an equilibrium for vitamin D, and exposure to more sun, will not give you more vitamin D.
So if a pigmented person A exposes 10% of the skin for 2 hour, or exposes 10% of the skin for 5 hours, vitamin D will not differ much, because width both equilibrium is reached in the sun exposed skin.

If this pigmented person exposes 60% of the skin for 2 hours, vitamin D production will be around 6 times higher than compared to 10% exposure for 5 hours.

Maximal amount will be around 10000IU for whole body exposure in UVB light.

[RRM]

So, from this study we can conclude that a level of 36.4 nmol of 25(OH)D is a safe level,Right?

Depens on how much clothes they were wearing.

These are farmers.
People have been wearing clothes for thousands of years.
It has been shown that potentially, humans can adapt to lower sunshine exposure to the extend of about 7.5 nmol / L per 400 years. Signorello LB
So, plenty of time for developing 25(OH)D levels much higher than 36.4 nmol / L,
even more so because some body parts (extremities) of these farmers daily get hours of direct tropical sunlight exposure.
And yet, average serum 25(OH)D in tropical countries is mostly 'low'.

For thousands of years, many, many peoples all over the world have been living in less sunny countries,
or have been living in thick forests, and/or have been wearing clothes for various reasons.
For thousands of years.
So that people in general have had plenty of time to adapt to less sunlight exposure.
So much so, that more sunlight exposure leading to increased serum 25(OH)D, one is more likely to get kidney stones.
(and accelerated aging of the skin, skin cancer)

[dime]

Something that clearly demonstrates what kind of damage can direct sun do over many years: http://www.nejm.org/doi/full/10.1056/NEJMicm1104059 , http://www.dailymail.co.uk/news/article ... -face.html

What are your thoughts on using a tanning bed in winter?
More specifically beds with narrowband UVB bulbs? Phillips TL/01 are the most advanced as far as I know.
These bulbs give you the range needed for vitamin D production, while minimizing cancer risk, sunburns, etc. In other words they are more or less safer than going out on the sun.

You need sun light for vitamin D production, but only a small fraction of the sun light spectrum is actually necessary (max production at UVB 302nm). In nature we can't separate the spectrum into what we need and what we don't need. So we have to go through quite some damage in the skin caused by most of the sun light spectrum, to get that benefit of producing vitamin D. It's probably the best compromise in lack of better ways. Of course we don't know if other wavelengths are necessary for producing other stuff, but at least the range for vitamin D seems well established.

[RRM]

"In broadband UVB treated patients, 25(OH)D3 increased 83%, compared to 59% in patients treated with NB-UVB." Osmancevic A et al
But of course, the broadband has more harmfull side effects.
And, of course, more may not be better.

"Full body NB-UVB three times per week is more effective in treating vitamin D deficiency than prescription of a daily oral intake of 1600 IU (40 μg) vitamin D(3)" Bogh MK et al
"A short NB-UVB course is an effective way to improve vitamin D balance in winter and the response is still evident 2 months after the course".Ala-Houhala MJ et al
"NB-UVB therapy may improve systemic inflammation markers, not mediated by vitamin D synthesis." Romani J et al
It also "increases cathelicidin and decreases HBD2 levels in healing skin lesions of psoriasis and atopic dermatitis".Vähävihu K et al
Vitamin B9 status is not influenced. Cicarma E et al

But we may have fully adapted to the vitamin-D related effects of the winter.
Research has shown that humans are highly adaptive regarding sun exposure-related vitamin D metabolism.

Though the body also adapts to the influence of the NB-UVB:
"After an initial 10 nUVB treatments, 25(OH)D serum concentration increased by 68% for winter patients, and 20% for the summer patients.
The next 10 treatments caused a much lower increase in 25(OH)D concentration: 5% and 3.5% for the winter and summer patients, respectively." Lesiak A et al

Phillips TL/01 are the most advanced as far as I know.
These bulbs give you the range needed for vitamin D production, while minimizing cancer risk, sunburns, etc.

"The narrowband Philips TL-01 lamp which is commonly used as UVB source for phototherapy of psoriasis has maximum spectral irradiance at around 311 nm which is presumed to be, however, of lesser importance in photochemical activation of the vitamin D(3) pathway.
...
maximum calcitriol-generating capacity of the TL-01 lamp at 500 mJ/cm(2) and 16 h after irradiation still amounts up to 44% of that found after monochromatic irradiation at 300+/-2.5 nm and 30 mJ/cm(2)." Lehmann B et al

[dime]

Potential Immune Benefits of Strong Vitamin D Status in Healthy Individuals
http://www.sciencedaily.com/releases/20 ... 212824.htm

The study, published online in PLOS ONE, reveals for the first time that improvement in the vitamin D status of healthy adults significantly impacts genes involved with a number of biologic pathways associated with cancer, cardiovascular disease (CVD), infectious diseases and autoimmune diseases.
...
At the end of the pilot, the group that received 2000 IUs achieved a vitamin D status of 34 ng/mL, which is considered sufficient, while the group that received 400 IUs achieved an insufficient status of 25 ng/mL.

The results of the gene expression analysis indicated statistically significant alterations in the activity of 291 genes. Further analysis showed that the biologic functions associated with the 291 genes are related to 160 biologic pathways linked to cancer, autoimmune diseases, infectious diseases and CVD.

If I convert my status of 40.4 nmol/L, I get a level of 16.1 ng/mL, i.e. I'm vitamin D defficient according to the guidelines (< 20ng/mL). Anyway, I have a few of those Philips bulbs and do 2-3 min/day tanning, so I'm curious to see if it improves the levels.

[RRM]

Actually, acording to the standards, most people worldwide are vitamin D insufficient,
even in sunny countries.
Thus, it might be that these guidelines are incorrect, and as higher levels are not necessarily safe,
the adagium "better safe than sorry" may be inappropriate here...

Just take a look at those studies i posted.
Your 40.4 nmol/L is not that low at all, in comparison.
It may actually be very safe.

[dime]

Yeah I get your point. I don't know, I already bought these bulbs and they were very expensive, so I'm feeling kinda compelled to make use of them. And I don't believe there's any danger sun tanning with them for 2-3 minutes once in a few days, especially since I'm anyway stuck indoors most of the time. But this topic definitely deserves more thought..

[Kasper]

Actually, according to the standards, most people worldwide are vitamin D insufficient,
even in sunny countries.

Please give reference to this claim. What do you mean with most people ?
Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l
http://journals.cambridge.org/action/di ... id=8735073

Thus, it might be that these guidelines are incorrect, and as higher levels are not necessarily safe,
the adagium "better safe than sorry" may be inappropriate here...

Come on, why are you so afraid of vitamin D? We evolved for thousand of years at UVB exposure.
Dime tells that he get very little ubv exposure as he is indoors most of the time.
Of course it is healthier to get 2/3 min of ubv exposure a day then 0 min of UVB exposure.

[RRM]

Actually, according to the standards, most people worldwide are vitamin D insufficient,
even in sunny countries.

Please give reference to this claim. What do you mean with most people ?

Half the world population.
Of course, it depends on your definition. Using a fairly conservative definition (< 40 nmol/L)
"Vitamin D insufficiency affects almost 50% of the population worldwide." Nair R et al
"If the more generous definition of this condition is used (serum 25-hydroxyvitamin D < 80 nmol/L), a much larger proportion of the population has the problem". Hanley A et al

Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l
http://journals.cambridge.org/action/di ... id=8735073

That was the first study on my list (of serum vitamin D in sunny countries).
Did you forget about all the other data in that very same post?
viewtopic.php?f=17&t=1569&p=33372#p33372

Come on, why are you so afraid of vitamin D?

Its more about weighing the pros (health benefits) and cons (skin damage / wrinkles) of sunlight exposure.
If i was afraid of vitamin D, i wouldnt be eating 300 grams of wild salmon daily...

We evolved for thousand of years at UVB exposure.

Exactly. The human body has shown to be very adaptive regarding sunlight exposure and serum vitamin D.
(to the extend of about 7.5 nmol / L per 400 years. Signorello LB)
So, if the body is so adaptive, why does it maintain such (relatively) low blood levels?
Even in sunny countries...
Since the human body is so adaptive, it can hardly be seen as a lack of adaptation (to less sunlight exposure).

[Kasper]

That was the first study on my list (of serum vitamin D in sunny countries).
Did you forget about all the other data in that very same post?

I didn't, but I do think this study is gives a good indication about the vitamin D concentrations we may evolved at.

Actually, acording to the standards, most people worldwide are vitamin D insufficient,
even in sunny countries.

If people are deficient of vitamin D in sunny countries then this is very likely caused by clothing habits (such as the ethiopian study).
It is also know that some surfers at Hawai, for example, don't absorb much vitamin D by the skin, because they only get sun exposure when they are in the water.
The vitamin D they create in the skin is imdediatley "diluted" by the water. They hide sun exposure for the rest of the day.

This doesn't imply at all that we evolved at low vitamin D concentrations.
The studies of hunter and gatherers (with a lifestyle we evolved at) show vitamin D levels around (58-171).
I don't see any reason why you're suggesting that dime shouldn't raise his vitamin D level above 40 nmol/L.
In evolutionary sense, this is a very low vitamin D level.

So, if the body is so adaptive, why does it maintain such (relatively) low blood levels?
Even in sunny countries...

Clothing habits, overexposure to water, being indoors most of the time, etc. etc.
People that live a traditional lifestyle, a lifestyle we evolved at, then vitamin D level isn't low at all.