[Sean Moore]

Sean Moore  asked the Naked Scientists:

Hey Chris,

I love the show. Only a fool couldn't.

Does my body still produce vitamin D if I'm wearing sunscreen? Or does this inhibit it?

Blue skies,

Sean Moore
-Winnipeg, Manitoba, Canada

What do you think?

[iko]

It's never too late (sometimes)...
If you followed this thread so far,
you deserve to watch this free video:

"The Vitamin D Pandemic and its Health Consequences"

Presented by Michael Holick, PhD, MD, Professor of medicine, physiology and biophysics
and director of the General Clinical Research Center at Boston University Medical Center
Keynote address at the opening ceremony of the 34th European Symposium on Calcified Tissues, Copenhagen 5 May, 2007

http://www.uvadvantage.org/portals/0/pres/

Hi Sean More,

find the answer in this interesting overview on vitamin D by Prof. Michael Holick:
certain sunscreens stop 99% ultraviolet B radiation, causing 99% drop in vitamin D production by the skin.
I'll find out the slide and data for you, but it will take some time...

Try to start from:   http://www.vitamindcouncil.com/

First "Item of interest":

Video of Professor Michael Holick explaining the vitamin D revolution.
Michael Holick, a respected Vitamin D researcher recently gave keynote address about Vitamin D.
It is a great overview of the entire situation. Watch the video- The Vitamin D Pandemic and its Health Consequences

...it should work!   []

I'm watching it over and over...to improve my english of course!
(Joke, I love this stuff: even helicobacter connections are mentioned)

ikoD  [^]

http://www.uvadvantage.org/portals/0/pres/video/video/slides/slide128.jpg

http://www.uvadvantage.org/portals/0/pres/video/video/slides/slide129.jpg

http://www.uvadvantage.org/portals/0/pres/video/video/slides/slide134.jpg

[Karen W.]

Nice IKO!

Now I have often wondered the same thing especially cause I can't be in the sun without sun block.. I think mine is Factor 70 SPF and usually I use shade.. which is basically a total sun Block!

[iko]

Nice IKO!

Now I have often wondered the same thing especially cause I can't be in the sun without sun block.. I think mine is Factor 70 SPF and usually I use shade.. which is basically a total sun Block!

Well, get your 25(OH)Vitamin D levels checked soon and...
off you go into this new vitamin D ERA!
So far -officially- the best placebo in our brand new millennium.

ikoD  []  ...on behalf of prof. Holick  (whose video is always there to be watched!)

[Karen W.]

Well I found out the hard way.. Iko I just now finished my last dose of vitamin E . They checked me and I am finally caught up enough to stop supplements and she has changed my other meds that prevented me from being unprotected in the sun.. I am now under orders to get at least two 30 minute sessions in the sun a day without sunscreen, if possible.. to help keep my vitamin D up.. I spent 48 weeks of 50,000 units a week, taking it once a week. I can truly say I feel a lot better then I did... which says a lot!

[iko]

Hi Karen,

It is nice to hear from you...that you feel better!
You could switch to 50.000 units per month, avoiding a sudden 'drop' of this hormone.
Sessions in the sun can't be so effective: too many variables involved.
Take care,

Iko

[wolfekeeper]

I just now finished my last dose of vitamin E .

Presumably you mean vitamin D.

I am now under orders to get at least two 30 minute sessions in the sun a day without sunscreen, if possible.. to help keep my vitamin D up..

I think you mean two 30 minutes sesions in the sun a week.

You could do less if you go out in the middle of the day; but it will depend on the time of the year; during the winter, vitamin D production is much slower because UV-B which produces it, is more attenuated at the lower angles in the sky.

For vitamin D production you want your sun at midday- because you can go out for less time and it damages your skin less (because you get less UV-A total dose).

[wolfekeeper]

Does my body still produce vitamin D if I'm wearing sunscreen? Or does this inhibit it?

Vitamin D production is caused by UV-B. How much sunscreen blocks UV-B is specifically measured by the SPF factor.

It's more or less an exact ratio SPF-50 blocks all but 1/50th of the UV-B. So if you're out in the sun for an hour, and you have a SPF 15 sunscreen on, then you will produce as much vitamin D as if you had been out for 4 minutes (which would actually be quite a lot, vitamin D production is quite fast). If you had SPF 30 then it would be two minutes.

I think if you're out unprotected (in a bikini or swimming costume) for 10 minutes then your body can make about 10,000 IU. You need about 400 IU per day, and there's very little vitamin D in food (apart from a few like some oily fish like mackerel and salmon.)