Vegans, vitamin D and the sun

[Korn]

Teens Should Increase Vitamin D Intake by 1000 Percent to Avoid Deficiency, Say Researchers

[Korn]

BBC / Science & Nature:
Can tomatoes protect your skin?

[Korn]

Vitamin D: A Gene-Regulating Super Nutrient

[Korn]

Sunbathing 'slows ageing process'

Sunbathing 'slows ageing process'

By Nic Fleming, Science Correspondent
Last Updated: 4:52PM GMT 09 Nov 2007

90 per cent of the body's intake of vitamin D is created by exposure to the sun
Sunbathing can slow the ageing process by up to five years, according to new research.
Scientists have found that people who avoid the sun, or have inadequate vitamin D in their diet, are subject to genetic damage associated with ageing and age-related illnesses.
The effect of the damage is so great that those who lack vitamin D - often called the "sunshine vitamin" because 90 per cent of the body's intake is created by exposure to the sun - were biologically five years older than those with the highest levels.
Lead researcher Dr Brent Richards, from King's College, London said: "These results are exciting because they demonstrate for the first time that people with high levels of vitamin D may age more slowly than people with lower levels.
"This helps to explain how vitamin D has a protective effect on age-related illnesses such as heart disease."

More here.

[Korn]

Vitamin D Insufficiency Linked to Parkinson’s Disease

[Quantum Mechanic]

I've been concerned lately about vitamin D, not because of being vegan but because I've moved a lot north and I'm confused about how people here deal with the lack of sunshine in terms of vitamins. I'm used to southern CA, where there's more prolonged sunshine throughout the year, and "winter" doesn't really become noticeable until late December anyway.

I get 25-50% of daily recommended vit. D in fortified rice milk and stuff, and I know that some light penetrates the clouds, but I am always hooded (due to light sensitivity) and my left hand covered with a wrist brace so...how do people handle it, when I am used to getting lots of sunshine every day?

[Vegabond]

I've been concerned lately about vitamin D, not because of being vegan but because I've moved a lot north and I'm confused about how people here deal with the lack of sunshine in terms of vitamins. I'm used to southern CA, where there's more prolonged sunshine throughout the year, and "winter" doesn't really become noticeable until late December anyway.

I get 25-50% of daily recommended vit. D in fortified rice milk and stuff, and I know that some light penetrates the clouds, but I am always hooded (due to light sensitivity) and my left hand covered with a wrist brace so...how do people handle it, when I am used to getting lots of sunshine every day?

If it's fortified, isn't that from the fish oils and other animal products?

[Korn]

D2 is derived from plants, D3 is not. (The vitamin that comes from sunlight exposure is D3).

Both Vitamin D Forms D2 And D3 Work Equally Well
Vitamin D3 more potent than D2, further evidence
Vitamin D2 Is As Effective As Vitamin D3 In Maintaining Concentrations Of 25-hydroxyvitamin D, Study Suggests

[Vegabond]

D2 is derived from plants, D3 is not. (The vitamin that comes from sunlight exposure is D3).

Both Vitamin D Forms D2 And D3 Work Equally Well
Vitamin D3 more potent than D2, further evidence
Vitamin D2 Is As Effective As Vitamin D3 In Maintaining Concentrations Of 25-hydroxyvitamin D, Study Suggests

Ok so is this D2 readily available now? I thought we are waiting for these Super mushrooms?

[Quantum Mechanic]

Ok so is this D2 readily available now? I thought we are waiting for these Super mushrooms?

The rice milk, soya milk, hemp milk, and almond milk I get are fortified with vitamin D2 (you have to be careful to check that it's not D3, because then that means that it came from an animal - I did this the other day because I mistook the 3 for a 2, and they didn't give a receipt so I called and they let me exchange it anyway). But yeah, most of them don't seem to have D3 - I think 8th continent tends to, but I've never seen it in person.

[Vegabond]

The rice milk, soya milk, hemp milk, and almond milk I get are fortified with vitamin D2 (you have to be careful to check that it's not D3, because then that means that it came from an animal - I did this the other day because I mistook the 3 for a 2, and they didn't give a receipt so I called and they let me exchange it anyway). But yeah, most of them don't seem to have D3 - I think 8th continent tends to, but I've never seen it in person.

Ok so after a quick read my understanding is that D2 is synthetic. I always thought that Vitamin D only came from two sources, the sun and animal products. Sure there is the fungal type but I thought it wasn't available to the public yet. I think I am going to walk everyay for 1/2 hour instead of hitting the gym. Sunlight and excercise!

Basically there are two types of oral vitamin D supplements. The natural ones are D3, and they contain the same vitamin D your body makes when exposed to sunshine. The synthetic ones are vitamin D2, which are sometimes called ergocalciferol.
Once either form of the vitamin is in your body, it needs to be converted to a more active form. Vitamin D3 is converted 500 percent faster than vitamin D2. Interestingly, it was previously thought that the kidney exclusively performed this function, as least that is what I was taught in med school.
However, in 1998 Dr. Michael Hollick, the person who discovered activated vitamin D, showed that many other cells in your body can make this conversion, but they use it themselves, and it is only the kidney that makes enough to distribute to the rest of your body.
While there have been no clinical trials to date demonstrating conclusively that D2 prevents fractures, every clinical trial of D3 has shown it does.
However, nearly all the prescription-based supplements contain synthetic vitamin D2, which was first produced in the 1920s through ultraviolet exposure of foods. The process was patented and licensed to drug companies for use in prescription vitamins. In case you didn't know, the vitamin D that is added to milk is NOT D3 but the highly inferior vitamin D2.
The study linked above concluded that "vitamin D2 should no longer be regarded as a nutrient appropriate for supplementation or fortification of foods."
That being said, optimizing your sun exposure and levels of vitamin D3 may, indeed, be one of the most important physical steps you can take in support of your long-term health. Conventional medicine is finally beginning to get on board the vitamin-D3 bandwagon, using the natural power of sunshine to treat type 2 diabetes, osteoporosis during a woman's pregnancy and even tuberculosis.
It is important to understand that the ideal and STRONGLY preferred method of increasing your vitamin D3 level is through appropriate sun exposure. I really do not advise oral supplements, not even cod liver oil now, UNLESS you can have your blood levels regularly monitored.
It just is too risky. I have seen too many potentially dangerous elevations of vitamin D levels, including my own, from those that are taking oral supplements.
But when you get your vitamin D from appropriate sun exposure your body can indeed self-regulate and greatly reduce vitamin D production if you don't need it, which makes it very difficult to overdose on vitamin D from sun exposure.

Woohoo my soya milk is fortified with D2...thanks guys. Now I just have to find a margarine substitiute (Dang Fleishmann's uses D3)

[Korn]

Prenatal vitamin D linked to kids' dental health
An excerpt from the article:

The study team enrolled 206 women during the second trimester of pregnancy "as that is when primary teeth begin to develop and calcify," Schroth explained in comments to Reuters Health. They measured vitamin D levels in the women's blood at enrollment and then followed them until their infants were around 1 year old.

Only 21 women (10.5 percent) were found to have adequate vitamin D levels. The average vitamin D level was about half what is considered adequate, the investigators found.

Among 135 infants who had their teeth checked by the team, roughly 22 percent had noticeable enamel defects and about 34 percent had early childhood tooth decay.

Mothers of children with enamel defects in their primary teeth had lower average vitamin D levels than those of children without enamel defects, but the difference was not significant from a statistical standpoint.

However, mothers of children with early tooth decay had significantly lower vitamin D levels during pregnancy than mothers whose children did not develop early tooth decay.

More here.

[bradders]

I burn incredibly easily, a little time in the sun in winter last year in New York without sun cream left me sunburnt. In summer following the guidelines with spf50+ spending no more than an hour over the day in the sun, keeping covered etc I can still get a bit pinker. Now I've run out of pre vegan sun cream I'm wondering if anyone knows of high spf products that are vegan as I can't find any anywhere. I'm quite worried for the coming summer if I can't find anything.

[cookey]

I use these ones for me and the children:
http://www.yaoh.co.uk/hemp-sun-block.html

You'll be able to pick them up at Brighton Fayre. The highest is SPF30 - I don't know if this is high enough?

[cookey]

.

[bradders]

Well it's better than nothing and is a great start but really I need something closer to the spf50 mark

[Quantum Mechanic]

Sorry that I can't help with vegan sunscreens, but one of the studies linked above suggested that a diet high in tomatoes (especially tomato paste) can reduce burning. I don't know if your diet is high in tomatoes or tomato paste or not, but it could be worth a try, as an addition to the sunscreens (obviously not as a replacement).

[dostoyevsky]

I've been reading up a lot on vitamin D deficiency and it would appear that a huge percentage of people in the northern hemisphere are vitamin D deficient. This is because the sun is only strong enough between the months of may and october for the skin to produce it. Even then, you need to get around 20-30 mins in the sun in the early morning and late afternoon... something that isn't easy for those who have 'normal' indoor jobs.

Now normally Vitamin D can be supplemented. There are 2 types; D2 and D3. From the research I've read though it appears that Vitamin D2 is highly inferior to Vitamin D3, to the point where it is practically useless. So here is the problem... vitamin D2 is vegan but vitamin D3 is not.

I am a strict vegan but this has really got me considering taking the vitamin D3 supplements. Vitamin D deficiency can cause a huge number of diseases from cancer to heart disease. The main problems I'm worried about at the moment though are depression and other mental disorders. Also, taking vitamin D3 could help with my acne which is also a huge issue for me. So I'm thinking about taking this supplement which comes from sheeps wool but at the same time, I'm feeling guilty.

Does anyone have any thoughts on this? Or does anyone know how you can obtain vitamin D3 while still sticking with the vegan lifestyle?

[harpy]

I thought the jury was still out on the relative effectiveness of vitamin D2 and D3:

http://www.sciencedaily.com/releases...0102122306.htm

Have you tried taking vitamin D2?

[Korn]

Considering becoming a non-vegan

So - you consider continue being a vegan with the possible exception that you will supplement with D3 in the darkest months (minus the period where the vit. D reserves in the body is being utilized)? Vit D normally has a half-life of 20-29 days.
Cows get vitamin D in the winter from sun-dried hay, and it's quite likely that humans traditionally used a lot more sun-dried plants in the winter than we do now...

Even then, you need to get around 20-30 mins in the sun in the early morning and late afternoon... something that isn't easy for those who have 'normal' indoor jobs.

Have you consider getting a job that will allow you to get more sunlight?

Considering becoming a non-vegan
I've been reading up a lot on vitamin D deficiency and it would appear that a huge percentage of people in the northern hemisphere are vitamin D deficient

If a huge percentage of (non-vegans) people in the Northern hemisphere are vit D deficient, does it really make sense to.... never mind. ;-)

Did you know that housed animals need supplements in the winter, unless they get enough vit D from... eg. dried plants?

Did you know that if everybody should follow advice about getting vitamin D and Omega-3 from fish, they wouldn't be able to get it because there simply isn't enough fish in the ocean?

This is also interesting: "The ongoing work so far has found that a single serving of white button mushrooms the most commonly sold mushroom will contain 869 percent the daily value of vitamin D once exposed to just five minutes of UV light after being harvested . If confirmed, that would be more than what's in two tablespoons of cod liver oil, one of the richest and most detested natural sources of the vitamin, according to the National Institutes of Health."

Some more info that may interest you:

http://ethesis.helsinki.fi/julkaisut...a/theeffec.pdf
"It has been evident since the beginning of 20th century that in vertebrates vitamin D3 is produced also endogenously
by UVB-light (290-315 nm) from the cholesterol-like precursor, 7-dehydrocholesterol,
present in the skin epidermis. Thus, in a strict sense, vitamin D is an essential nutrient
only when sunlight exposure is limited. Vitamin D2 and D3 are both biologically
inactive themselves but after hydroxylations in the liver and kidney they become
biologically active. Although it has been shown that the absorption of vitamin D3 is
better than vitamin D2 (Trang et al 1998), active vitamin D2 and vitamin D3 metabolites are, however, assumed to have the same biological activity in humans. "


http://www.biodirectory.it/show_acti...activityId=856
"Several plants, e.g., Solanum malacoxylon, have been shown to contain varying amounts of vitamin D3 and the related hydroxylated metabolites, 25-hydroxy vitamin D3 and 1α,25-Dihydroxy vitamin D3 (1a,25(OH)2D3 ). "

Here's another one: "However there is evidence for production of vitamin D3 in plants. "

http://books.google.com/books?id=bNH...#PRA1-PA254,M1
"Exposure of the provitamins to sunlight results in the conversion to ergo- calciferol (vitamin D2) and cholecalciferol (vitamin D3) in plants and animals, ..."

http://www.sicytar.secyt.gov.ar/busq...cod=0000891703 :"Various flowering plants have been shown to contain 1a,25(OH)2D3 and related vitamin D3 metabolites as detected by highly specific and sensitive biological and chemical procedures. "

http://resources.metapress.com/pdf-p...u&size=largest : "There is evidence for similar biosynthetic pathways in plants, as pro-vitamin D3, vitamin D3, calcidiol, and calcitriol, have been identified in a wide range of plant species and have been characteristic of Angiosperms [...]"



We know that w need D3, we know that we don't get the sunlight we used to get when we were all working outdoors and living in sunnier climates, we know that we can get vitamin D from sundried plants (and that there is evidence for production of vitamin D3 in plants).... We just don't know much about it yet.

Science is still in it's early childhood. Is that really a reason for being responsible for taking other living being lives?

[Prawnil]

From the research I've read though it appears that Vitamin D2 is highly inferior to Vitamin D3, to the point where it is practically useless.
...
Does anyone have any thoughts on this?

Yes. Primarily, that it would better to avoid making statements like the above without sharing their source with readers (just because it's a strong one to make).

Now, sorry, for a paper-gush.
-----
Trang HM et al., 1998. Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2 American Journal of Clinical Nutrition [1]

" The increase in 25(OH)D with vitamin D3 ...[was] 1.7 times the increase obtained with vitamin D2 ... Although the 1.7-times greater efficacy for vitamin D3 shown here may seem small, it is more than what others have shown for 25(OH)D increases when comparing 2-fold differences in vitamin D3 dose. The assumption that vitamins D2 and D3 have equal nutritional value is probably wrong and should be reconsidered. "

-----

Mistretta VI et al., 2008. Vitamine D2 ou vitamine D3?
Mouvement thérapeutique [2]

" At the present time, the vitamins D2 and D3 are not equivalent. Indeed, to reach the same serum concentration of 25(OH)D, it is necessary to triple the amount of D2 compared to its counterpart D3. D2 should no longer be regarded as being suitable for the supplementation or the enrichment of food. (Dodgy translation from the French)"

-----

Zarowitz BJ, 2008. The value of vitamin D3 over vitamin D2 in older persons
Geriatric Nursing

" Only a few studies have directly examined the relative potency of vitamin D2 and D3 using contemporary assays. Vitamin D3 is now known to be more efficacious than vitamin D2. Recent data have demonstrated that D2 (ergocalciferol) has lower bioactivity, poorer stability, and shorter duration of action, resulting in approximately 33% lower potency compared with vitamin D3 (cholecalciferol). Oral calcium and vitamin D supplements have been or are in the process of being reformulated with vitamin D3 rather than D2 "

-----
On the other hand:

Gordon CM, 2008. Treatment of hypovitaminosis D in infants and toddlers
Journal of Clinical Endocrinology and Metabolism [3]

" Short-term vitamin D2 2,000 IU daily, vitamin D2 50,000 IU weekly, or vitamin D3 2,000 IU daily yield equivalent outcomes in the treatment of hypovitaminosis D among young children. ... no difference in efficacy or safety was noted among these three common treatment regimens. "

-----

And I think this may be the paper the article harpy posted was based on:
Holick MF et al., 2008. Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentration of 25-hydroxyvitamin D
Journal of Clinical Endocrinology and Metabolism [4]

" [It is] reported that a single dose of 50,000 IU vitamin D2 was less effective than 50,000 IU vitamin D3 in maintaining serum 25(OH)D levels ... We did not observe any negative influence of vitamin D2 on either total [total D] or [D3] levels. ... when 50,000 IU vitamin D2 was given weekly for 8 wk or twice a week for 5 wk, there was on average a 100% increase in serum ... levels and a significant increase in bone mineral density in both the hip and spine. Thus, vitamin D2 when given in pharmacological doses is effective in maintaining serum 25(OH)D levels and is beneficial for skeletal health.
Why Trang et al. observed that the daily dosing of 4000 IU vitamin D3 for 2 wk was 1.7 times more effective in raising blood levels of 25(OH)D than 4000 IU vitamin [D2] ... is unclear at this time. ...
Thus, 1000 IU vitamin [D2] is as effective as vitamin D3 in maintaining 25(OH)D status. These observations are consistent with those of Markestad et al. and Rapuri et al. who observed that vitamin D2 and vitamin D3 contributed equally ... in mothers and their neonates and elderly women "

----

Even in the papers that conclude that D2 is not as effective as D3, the lowest figure I've seen is the one above suggesting a required triple dose to equalise. A one-third efficacy that isn't widely reported is not "practically useless" by any stretch of the imagination, so doesn't seem to be much of a reason to worry. Considered from the point of view of a regulator, following decent evidence that D2 may not be as efficient in raising the prehormones that D2&3 convert to, all things being equal (as in, in an omniverous population), it would make some sense to suggest that D2 be disregarded in favour of D3. Of course that wouldn't take vegans into account.
Sorry for the length.

[cobweb]

i've been a bit concerned about this as we had such a very dark winter here this year, i am so pale and tired, so is my hubby and my son.

Good to read the research you posted, Korn, is this a worry in your part of the world as i presume you must get even less daylight in the winter than we do in Orkney?. Or do you get nice bright winter sunshine?. Most of our winter days seemed grey this year.

[harpy]

I don't think it really matters how sunny it is; I've read that in winter time in northern countries, the sun doesn't get high enough in the sky for us to make vitamin D from it. I don't understand the physics though.

I try to remember to take those Veg-1 tablets most days in the winter - they have vitamin D2 as well as B12.

[veganwitch]

I burn incredibly easily, a little time in the sun in winter last year in New York without sun cream left me sunburnt. In summer following the guidelines with spf50+ spending no more than an hour over the day in the sun, keeping covered etc I can still get a bit pinker. Now I've run out of pre vegan sun cream I'm wondering if anyone knows of high spf products that are vegan as I can't find any anywhere. I'm quite worried for the coming summer if I can't find anything.

Total Block COTZ 58 sunblock is made w/ only titanium oxide and zinc oxide. I buy it for my husband from www.sunprecautions.com. That company also makes clothes / hats w/ sunblock built right into them, but tbh, I don't know if the sunblock in the clothes is vegan.

[bradders]

do you know about the testing though as I can't see any info about that on their website. I have seen other creams that are vegan in terms of ingredients but none that are of a really high spf that are not tested on animals.

[cobweb]

I don't think it really matters how sunny it is; I've read that in winter time in northern countries, the sun doesn't get high enough in the sky for us to make vitamin D from it. I don't understand the physics though.

I try to remember to take those Veg-1 tablets most days in the winter - they have vitamin D2 as well as B12.

i find them hard to swallow (i'm wussy with pills) so i take the seven seas vegan society approved ones but i did wonder if they were really effective

[veganwitch]

do you know about the testing though as I can't see any info about that on their website. I have seen other creams that are vegan in terms of ingredients but none that are of a really high spf that are not tested on animals.

sorry, i don't know about the testing

[harpy]

Cw, the Veg-1 ones are meant to be chewy, not swallow-y. You may or may not like the taste though Don't see why the Seven Seas ones would be ineffective?

The whole area is surrounded by controversy as you may have noticed but I feel that taking a vitamin D supplement now and then in winter is likely to do more good than harm - until They change their minds of course

[cobweb]

Cw, the Veg-1 ones are meant to be chewy, not swallow-y. You may or may not like the taste though Don't see why the Seven Seas ones would be ineffective?

The whole area is surrounded by controversy as you may have noticed but I feel that taking a vitamin D supplement now and then in winter is likely to do more good than harm - until They change their minds of course

oh, yes, it's the Veg-1 tablets that taste icky, i have had them from the VS but passed them on to my hubby
i was thinking of the Deva ones i also more recently passed on to my hubby
i really meant that i don't know if any vitamin supplements, especially vit d, are truly effective, but as you say, i think i prefer to take them anyway.

[Mahk]

I don't think it really matters how sunny it is; I've read that in winter time in northern countries, the sun doesn't get high enough in the sky for us to make vitamin D from it. I don't understand the physics though.

Several factors besides your latitude, sun elevation, time of day, and time of year, come in to play. Skin color for instance has a profound effect. Black people need five to ten times the exposure time to make the same amount of vitamin D as white people, so if a white person living in the UK in the winter needs two hours of mid day sun a black person would need at least 10 hours of, um, "mid day sun".

Here's a handy dandy sun exposure time calculator to manufacture your DV (daily value) of vitamin D .

Before you can use it you need to know if you are black, white, or what shade of grey you fall in according to the Fitzpatrick skin type color index. You can determine that here.

You also need to know your latitude and longitude. You can determine that here.

I just tried myself and input my lat/long and skin type 2, surface concrete dry, elevation .1 kilometers, I left all the other preset examples alone but I changed the weather to scattered clouds, instead of clear skies , because I think that is much more common day to day and I put in my body exposure as 10% (face alone, hands need gloves this time of year). The answer came back 26 minutes of midday sun to get 1000 IU. Not too bad, doable, and much better than I had thought. But then I realized the preset date was April 14th, so I fixed that to today's date instead. The answer came back at a whopping 4 hours!

[This last paragraph was me quoting myself from another post]

[Gorilla]

I've been reading up a lot on vitamin D deficiency and it would appear that a huge percentage of people in the northern hemisphere are vitamin D deficient.

have you been tested to find out if you actually are deficient in vitamin D?

do you realise that many common foods are supplemented with vitamin D - generally D3 - so why would so many people still be deficient if supplementing does any good at all?

mental health problems are not always rooted in any one definite cause. have you tried sun-lamps for your acne?

[harpy]

Interesting point - presumably a sun lamp would allow your body to make the requisite amount of vitamin D in winter. Although then there is the thing about balancing vitamin D requirements with the risk of skin cancer. Aaargh!

[herbwormwood]

I don't think it really matters how sunny it is; I've read that in winter time in northern countries, the sun doesn't get high enough in the sky for us to make vitamin D from it. I don't understand the physics though.

Courtesy of astronomy website:

The sun's rays are weak in Winter due to the tilt of the Earth's axis relative to the plane of its orbit.

The tilt of the Earth's axis affects

• The amount of direct sunlight (Insolation)
• The length of the day.

When you consider that in Summer the Sun is rising at around 5.30 am and not setting until 10 ish, there is going to be a lot of sunlight, and the opposite happens in Winter.

[Korn]

Yes, sun lamps are known to boost vit. D levels.

This is because the sun is only strong enough between the months of may and october for the skin to produce it.

That depends on where you live....

From the research I've read though it appears that Vitamin D2 is highly inferior to Vitamin D3

The part of a vit. D pill that actually consist of the actual vitamin is microscopic, so even you would have to have a three times as high vit D amount, or ten times as high, you wouldn't really notice. You'd still only have to take one pill daily...

[harpy]

This one adds:

"Daily changes in the angle of the Sun influence the amount of UV radiation that passes through the atmosphere. When the Sun is low in the sky, its rays must travel a greater distance through the atmosphere and may be scattered and absorbed by water vapour and other atmospheric components. The greatest amount of UV reaches the Earth around midday when the Sun is at its highest point."

[Mahk]

The part of a vit. D pill that actually consist of the actual vitamin is microscopic, so even you would have to have a three times as high vit D amount, or ten times as high, you wouldn't really notice. You'd still only have to take one pill daily...

I'm lost. Please elaborate. What's your point?

Thanks.

[harpy]

I'm not Korn (obviously) but I read that as meaning that if vitamin D3 is assumed to be three times as potent as vitamin D2 then a vitamin D2 tablet could be made as effective as a vitamin D3 tablet by including three times the amount of active ingredient, and that this would make no noticeable difference to the tablet because the active ingredient would still represent a very small proportion of the tablet

[Korn]

That's what I meant. It was a comment to the relevance of whether it had any significance at all if one needed a few micrograms extra of one of the types of vit D.

[Mahk]

Oh I see.
---

Vitamin D can be toxic if taken in mega doses. I doubt 3X would get one in big trouble but 10X sounds risky. hmm...


Off to cyberspace I go...

I'm back. It's cold; wear a jacket.

Excessive dietary intake of vitamin D can be toxic. Toxicity of vitamin D can come from either its plant-based (D2) or animal-based (D3) form. Symptoms of toxicity include loss of appetite, nausea, vomiting, high blood pressure, kidney malfunction, and failure to thrive.

In 1997, the National Academy of Sciences set Tolerable Upper Intake Levels (ULs) for vitamin D as follows: infants, 0-12 months, 25 micrograms (1,000 IU) per day; children and adults, 50 micrograms (2,000 IU) per day; pregnant and lactating women, 50 micrograms (2,000 IU) per day.

Individuals with hyperparathyroidism, overactivity of the parathyroid gland, are at increased risk for vitamin D toxicity, and should not take supplemental vitamin D without consulting a physician.

Source.

[Korn]

doubt 3X would get one in big trouble but 10X sounds risky

Sure, but if one would take eg. ten times more of a kind of vit D (D2) that required ten times more to get the same affect as a 'standard' amount of another kind of vit. D (D3), don't you think that one also would have to take ten times more to reach to the level where overdosing could be troublesome?

I'm not recommending overdosing on anything, I'm just looking at what a 'normal' amount of D2 would be , and what a 'normal' amount of D2 would be.

One cannot overdose on the D3 that is generated by sunlight.

Vit D is to some extent stored in the body. Maybe person who would spend more time outdoors than the average person (who spend most of his life indoors at work, in a car/bus/train, or indoors art home) would have a so much larger storage of vit. D when the winter arrives that even when reaching the 'half-life' level (see above) he would have enough.

And maybe, if he works outdoors for several hours every day, all year round, there would be a little vit D generation even from a possibly tiny level of UV radiation in the darkest months. I'm only guessing here, because I haven't seen any studies about this - I just know that most general recommendations are meant to represent amounts that are relevant for 'most people, most of the time'.

[Mahk]

Sure, but if one would take eg. ten times more of a kind of vit D (D2) that required ten times more to get the same affect as a 'standard' amount of another kind of vit. D (D3), don't you think that one also would have to take ten times more to reach to the level where overdosing could be troublesome?

No, they aren't necessarily correlative at all. [Not that I'm an expert in such matters]
The mechanism that causes a compound to be healthy for you in the right quantities may be entirely unrelated to how it is toxic for you in higher doses.

Take for example iodine. A deficiency of it will cause goiter (an inflammation of the thyroid in the neck causing a large bulge) and is the leading cause of brain damage [says the WHO], but an overdose can kill you for reasons unrelated to the proper brain or thyroid function. They are happy and content while other parts of your body are in turmoil due to the overdose.

From my cursory googling about it would seem that hypervitamindosis D causes hypercalcemia (too much calcium in the blood) with symptoms of:

Constipation
Decreased appetite (anorexia)
Dehydration
Fatigue
Irritability
Vomiting

I'm sticking to the UL's I posted in my last post, personally.

One cannot overdose on the D3 that is generated by sunlight.

True, but sunburn, premature aging and skin cancer should be considered as well; too much sun is bad for you. The only people who suffer from hypervitamindosis D naturally, without supplements, get it from excessive cod liver oil consumption. We obviously don't have to worry about that.

[Korn]

Sunbathing 'could boost your intellect and prevent dementia'

[bradders]

But they stressed their findings should not spur people to bask in the sun, which can increase the risk of skin cancer.

I think the most important thing here is that we ensure that we get enough vitD from our food sources rather than relying on the sun.

[Quantum Mechanic]

I think the most important thing here is that we ensure that we get enough vitD from our food sources rather than relying on the sun.

??? I was under the impression that the only food sources for vitamin D were fish (and maybe something else, but it definitely wasn't vegan - and even cow's milk, another non-vegan item, gets the vitamin D as a supplement, fortified with it). When D2 is in rice milk or margarine or such, aside from fish I only recall seeing it as a fortified part of food when it's not in a supplement bottle. There was some mention of something like sun-dried mushrooms or something that I'm not familiar with, but that's not exactly a part of most people's everyday diet.

[Korn]

I think the most important thing here is that we ensure that we get enough vitD from our food sources rather than relying on the sun.

The sun is normally considered being considered the most important source of vitamin D for both vegan and non-vegans...

[Quantum Mechanic]

Of course, there should be appropriate caution to avoid the overexposure that would put one at elevated risk of skin cancer. One doesn't want ricket's, but one doesn't want a basal cell carcinoma or melanoma either.

[bradders]

I wasn't saying that we shouldn't get exposure to the sun (though the sun is quite dangerous for me as it happens) rather that as so many people live in different climates now than their skin is designed for, we live longer and damage is cumulative to a degree and we spend considerable amounts of time indoors, in offices etc that we can't rely principally on the sun even if that is the best source. The sun is also quite dangerous and must be respected accordingly. We can get vit D from a vegan diet, many plants contain reasonable levels of vitamin d2 and many products are also fortified so provided you ensure that you get enough from your diet there is no need to expose yourself to too much sunlight. (I myself have very sun sensative skin and have a non-regenerative form of vitiligo, early stages yet that sun exposure can make much worse).

[cobweb]

But is it true that the plant form of vit D isn't as 'effective' as the animal based form? (obviously i am not advocating eating animal parts!!). I do worry slightly about this as its so dark here in winter.

[bradders]

it is true that D2 is less effective than D3 as it requires more work by our kidneys and liver, however we can still eat enough and with some sensible sun exposure there shouldn't be any problems.

[cobweb]

ah, right - would any bright light trick your brain into producing it, e.g full spectrum lamps? (sorry to ask dumbass questions)
I'm getting one of those pratty looking SAD visors for myself and hubby this Christmas.