Thursday, December 31, 2009
The most important place to start to determine how much D you needed is to have your vitamin D storage levels checked. This test will tell you if you are sufficient, insufficient, deficient, or in the toxic level; but these numbers are a greatly debated subject among various D researchers and d...
Dear Pam,
Many thanks for the fascinating -- first time-- information about the calculator, which even gives the calculations for hands face etc. However there is one important question that needs to be addressed. When we say sunlight -- do we mean direct exposure to the bright sun in the sky as it stares down at us? Or do we mean simply sunlight, or daylight which we get even when there are clouds in the sky? I believe a saw a video by a professor who spoke of the rays of the sun in daylight itself, even when there are clouds in the sky and the sun is not visible in the daytime. Would you have anything to say to that? Also Dr. Cannell of the vitamin D council seems to think that you can get up to 10,000 to 20,000 IU of Vitamin D from a 10-15 minute exposure.
What do these people mean when they say exposure to the sun? Do they mean whole body exposure like a sun bath or simply sun on the face and hands when we walk around in the sun?
I suppose research needs to be done about the effect of sunlight on the head and skull -- does it promote hair growth through Vit D in the skull? I believe there are some who think so! Maybe someone should do a study on hair growth comparisons between Vit D deficient persons and those who move around in the sun without hats.
Thanking you for yet another enlightening post, please keep on the track on Vit D in subsequent parts III and IV and more!!! It is the hottest topic these days for the bones as well as the heart not to forget cancer and other diseases. And we need more enlightened posts from such an intelligent researcher like yourself to keep us on the track!
Yours,
Priya
Hi Priya, thanks for checking in and looking at the calculator. Be sure to read the link to Monica Reinagel's blog on how to fill out the calculator, and also all the comments at the end of the blog (46) that answers a lot of questions. I believe Ms Reinagel contacted Dr. Cannell to verify a couple of the questions asked. The commenter's were from all over the world, so of course they all got different exposure times for their location and weather condition.
You're given options for the type of weather you have on any given day, and time. To get the answer I did on it I put in the following info for yesterdays weather where we live.
1. Date
2. Longitude and latitude (if I lived in another location it will change the answer)
3. Skin type (I picked Darker Caucasian) this may have been wrong
4. Nature of exposure (around midday) if I put in 3:00 p.m., or some other time, I'd get a different answer
5. Sky condition (cloudless-since that's how it was yesterday) see the options on the calculator for this
6. UV index (I found this for a city nearby and it was 3)
7. Ozone layer thickness (I put medium, since that was the recommendation)
8. Surface altitude (this is converted into kilometers and our altitude is 2370 feet)
9. Surface type (I picked concrete-dry out of the options)
10. Press here to get the recommended UV exposure time
Now if I lived in another city north of the 35th parallel and it was snowing yesterday, the answer would have probably been = not enough UV exposure to get any vitamin D and I should take supplements; also changing the date or any other info will give you a different answer.
There are some flaws in this calculator since the only option for skin exposure where 3 small areas of the body. If you exposed more than your face, arms and legs you'd get more D.
I don't see how anyone could say how much D you'd get from the sun unless you knew all the answers above, and the amount of skin exposed which this calculator doesn't provide. You can also look into the handheld calculators they sell for this that should be more accurate since you are given more options for skin type etc.
I hope this helps. Maybe some day we'll know the answers to your other astute questions.
Thanks for posting... (If the html shows up above, sorry about that, I did use a text-editor to prevent this).
Hi Priya, I forgot one of your questions... "What do these people mean when they say exposure to the sun? Do they mean whole body exposure like a sun bath or simply sun on the face and hands when we walk around in the sun?"
They mean any type of exposure to your legs, arms and face. Whether you're sitting/lying still, walking, or engage in some sport. Unfortunately you can't get the amount of D you'd receive if you exposed more than that, which would be an optimal situation (exposing chest/back etc) which would provide more D.
Let us know if the blog and comments at Nutrition Data helps to clear some of this up.
Dear Pam,
Many thanks. I will read the calculator in detail although I am a bit sceptical as of now. The only sunlight I ever get is from my windows!! And I suppose that cuts off the ultra violet rays which give the Vit D. So mine would be zero!
What did you think of the professor's remark that any kind of daylight is sunshine. That even if there are clouds but it is day time -- you are getting ultraviolet light to make Vitamin D. He said that daylight means that the sun's rays are reflecting off all the subjects that you get to see - that is why we see the objects because of the rays of the sun that come from them, reflected sunlight.
Would you have any views on this? As a physicist I know that you cant see anything unless light reflects off its surface. But how strong are the ultraviolet rays in this reflected light from the objects around us in the day--how much Vit D would be get from them? This is the most common type of "sun" that most people get, especially when they are indoors most of the time, and in cloudy weather outside.
Thanks again, please continue with your digression on Vit D and go to the topic of calcification of the arteries as well as coronary artery disease which Vit D is supposed to help -- also the important topic whether you should CUT DOWN on the Calcium when yu take high doses of Vit D -- because when you take Vit D the calcium absorption is FOUR times than when you dont. This would mean that four times more calcium would be absorbed. And therefore -- would the chances of calcification go up?
Does a large amount of calcium in the blood cause calcification? Can Vit D act as a scavenger to remove calcium from the arteries and place it into the bones?
Pam, if with your knowledge and perspective for research you could pick on these topics it would be of great benefit to mankind!!
Yours,
Priya
Hi Priya, if you plug in differing answers to the weather conditons on the calculator you'll see how it effects the results. So, this would somewhat answer your questions about the type/amount of sun you are getting, if it's cloudless, scattered clouds, overcast etc. Changing each of these options provides a different result, so you should be able to gleen some info from these variables, and apply it to your situation. Are the windows where you are treated with something that blocks UV light? If not, you may be getting some D, but it would be best to go outside when the sun is out to get exposure. I know that windows here in the US are treated, and especially in cars. Have you ever thought about using a UV light? I know some who try this if they live where it rains a lot, maybe that could help.
I would agree that you still get some D even on an overcast day. I have nothing scientific to base this statement on, but I do know you can still burn your skin while sun bathing in semi-overcast weather, so theroretically you should also be getting some D as well, the problem is how much D??? The calculator will give you some idea about this if you calculate it with all the varying weather options provided and compare the varying results, side-by-side.
I'll try to find out more about your ever-growing interest in CAD and PAD, but so far you've found more convincing evidence than me. I can also check with a mineral metabolism Dr. to see what they say since that's there major area of study--how we metabolize minerals and vitamins. If you find any more evidence on your search let us know, and I'll do the same.
Thanks again for your constant interest and support!!
Dear Pam,
Many thanks for the clarifications! Now I know that we are getting Vit D even when we walk in cloudy weather!! I shall wait for more from you on Vit D.
Thanks again,
Yours,
Priya