Author Topic: Vitamin D  (Read 83683 times)

Offline kayell

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Re: Vitamin D
« Reply #45 on: June 16, 2010, 10:59:00 AM »
Does anyone know at what rate Vitamin D production from sunlight is reduced by decade or other age measurement? Are there any correcting factors for weight, health, cholesterol consumption, other issues?

I love the sun calculator and if all my stats were ideal (hah) I just made 2000 IU of D3 in 6 minutes of walking around the building, but I suspect it isn't that easy.

Offline Warren Dew

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Re: Vitamin D
« Reply #46 on: June 17, 2010, 10:14:46 AM »
Dr. Eades recently reviewed a book on vitamin D on his blog:

http://www.proteinpower.com/drmike/supplements/sunshine-superman/

Lots of good information there.


Offline motif

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Re: Vitamin D
« Reply #47 on: June 18, 2010, 03:10:04 AM »
So how many hours on the sun equals 400 UI of D3 pill???  ???
(not naked, just shorts and tshirt, or two hats...  :P)


Offline Eric

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Re: Vitamin D
« Reply #48 on: June 19, 2010, 11:07:04 AM »
So how many hours on the sun equals 400 UI of D3 pill???  ???
(not naked, just shorts and tshirt, or two hats...  :P)



Good question, but the GREAT question (at least for me) is how much sun do you get between November and March?  For me it's little to none!

Offline kayell

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Re: Vitamin D
« Reply #49 on: June 19, 2010, 02:20:42 PM »
The figures I had earlier for 3 minute exposure (South Carolina, mid-day, no clouds, June 16) came from the site below. Lovely calculator. I only wish it figured age since skin isn't as efficient at making D as it ages.

Yes, it's the best source of vitamin D. I posted this previously in the vitamin D thread under "Vitamins", but I'll post it here too. It's a vitamin D by sun calculator:

http://nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html


Offline Warren Dew

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Re: Vitamin D
« Reply #50 on: June 19, 2010, 02:45:22 PM »
Good question, but the GREAT question (at least for me) is how much sun do you get between November and March?  For me it's little to none!

According to Holick - whose book Eades was reviewing - midwinter sun doesn't produce vitamin D even at noon above a latitude of 35 degrees.  Here in New England, we only get vitamin D from sunshine about seven months out of the year.

I watched the first of these links, but it's a bit annoying as the pause control is invisible for most of the presentation on my browser.  The second link may be similar though I haven't watched it:

http://www.uvadvantage.org/portals/0/pres/
http://www.uctv.tv/search-details.aspx?showID=15773

Offline Eric

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Re: Vitamin D
« Reply #51 on: June 19, 2010, 04:37:03 PM »
Good question, but the GREAT question (at least for me) is how much sun do you get between November and March?  For me it's little to none!

According to Holick - whose book Eades was reviewing - midwinter sun doesn't produce vitamin D even at noon above a latitude of 35 degrees.  Here in New England, we only get vitamin D from sunshine about seven months out of the year.

I watched the first of these links, but it's a bit annoying as the pause control is invisible for most of the presentation on my browser.  The second link may be similar though I haven't watched it:

http://www.uvadvantage.org/portals/0/pres/
http://www.uctv.tv/search-details.aspx?showID=15773


Great information.  Thanks much, this further validates my 10,000 IU daily supplementation with Vitamin D all winter long

Offline Lone_woLf

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Re: Vitamin D
« Reply #52 on: June 19, 2010, 07:39:49 PM »
I thought that vitamin D is stored in the body for months, until we can get adequate sunlight again.

Offline Chris

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Re: Vitamin D
« Reply #53 on: June 20, 2010, 11:02:57 AM »
I thought that vitamin D is stored in the body for months, until we can get adequate sunlight again.
Vitamin D is a fat soluble vitamin, so it is stored in the body and used when needed. How long this vitamin D lasts depends on the amount you absorb when it is available and how much is used up during the winter.

Offline Warren Dew

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Re: Vitamin D
« Reply #54 on: June 20, 2010, 06:04:02 PM »
I thought that vitamin D is stored in the body for months, until we can get adequate sunlight again.

I think Marika once posted a link to a paper saying that the half life of vitamin D in the body was typically 3 months or so.  So yes, if you get enough in the summer - say by staying outside half naked all day - it may last you through the winter.

Me, I'm lucky if I get hand and face exposure for 15 minutes a day in the summer.  Last summer I got no sun exposure starting in July and I think I was showing signs of vitamin D deficiency by February or so.

I normally don't like supplements, but Holick's information definitely has me considering vitamin D supplements.
« Last Edit: June 20, 2010, 06:05:46 PM by Warren Dew »

Offline Khrystyna

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Re: Vitamin D
« Reply #55 on: June 22, 2010, 08:54:15 AM »
I don't know if someone mentioned it already but the amount needed is also dependent on your degree of body fat as it can become 'trapped' in your fat and become quite inaccessible. We looked at vitamin D a lot in my college as the head of the dept specializes in vitamin D research and the statistics for Ireland at least showed that the stores we generate in the summer months are nowhere near adequate to tide us through the winter, even when you're using a blood concentration at the very conservative end of the supposedly optimal level reccomendations. In 4 years of study, it was the only nutrient we were ever told people needed to supplement, even though they were keen for us to know an optimal diet would provide adequate amounts of every other nutrient. 

Offline Eric

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Re: Vitamin D
« Reply #56 on: June 22, 2010, 09:36:28 AM »
I don't know if someone mentioned it already but the amount needed is also dependent on your degree of body fat as it can become 'trapped' in your fat and become quite inaccessible. We looked at vitamin D a lot in my college as the head of the dept specializes in vitamin D research and the statistics for Ireland at least showed that the stores we generate in the summer months are nowhere near adequate to tide us through the winter, even when you're using a blood concentration at the very conservative end of the supposedly optimal level reccomendations. In 4 years of study, it was the only nutrient we were ever told people needed to supplement, even though they were keen for us to know an optimal diet would provide adequate amounts of every other nutrient. 

Game. Set. Match. 

Excellent information, thanks for sharing. 

Offline Lone_woLf

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Re: Vitamin D
« Reply #57 on: June 22, 2010, 10:06:21 AM »
Paynowlivelater has a new installment in the paleo in a nutshell series

Sunshine
http://www.youtube.com/watch?v=Mv1naIENqcE

here is also mercola's video on making sure your body absorbs the vitamin D you get from the sun, and do not use UVA tanning beds thinking you'll get vitamin D

EDIT:http://articles.mercola.com/sites/articles/archive/2009/05/12/Shocking-Update-Sunshine-Can-Actually-Decrease-Your-Vitamin-D-Levels.aspx

Mercola's web site sucks, here's the youtube video of the same.
http://www.youtube.com/watch?v=J1sTYuL-QsU

The only thing I'm concerned with is the wrinkling of my skin, which seems like it would result with any amount of UV exposure.
« Last Edit: June 22, 2010, 10:39:49 AM by Lone_woLf »

Offline ajmesa

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Re: Vitamin D
« Reply #58 on: June 22, 2010, 05:27:40 PM »
As far as wrinkling, if you are only concerned about your face/neck you can wear a wide-brimmed hat when you are outside. Back, chest, abs, and legs have enough surface area for adequate vit D production.

Some people might want to read this:

http://heartscanblog.blogspot.com/2010/06/increased-blood-calcium-and-vitamin-d.html

In short, don't supplement with calcium if you have proper vit D levels.

Offline Warren Dew

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Re: Vitamin D
« Reply #59 on: June 22, 2010, 07:12:28 PM »
The only thing I'm concerned with is the wrinkling of my skin, which seems like it would result with any amount of UV exposure.

I wonder how much sun actually ages the skin, and how much it merely causes the skin to look older due to the antiproliferant effect of the vitamin D.