steve wrote:
> Juergen Botz wrote:
>> Better yet... get plenty of sun.  If you do, your body will make the 
>> Vitamin D you need, and make it where it needs and how it
>> can best use it.
> 
> As one ages, even with enough sunlight, one will not make enough vitamin 
> D.  

I can't find any evidence of that in the literature.  Can you provide
some evidence to back up that claim?  What I do find is Vitamin D
deficiency in the elderly because of obesity (body fat absorbes Vit D,
in part irreversibly) and because they don't spend much time in the
sun.

> I would hazard to guess that if you take a group of 60 year olds 
> frolicking daily in Cancun, and give one half of them 2000 IU of vitamin 
> D, that the those getting the vitamin D supplementation will have a 
> cancer mortality at 50% or less of those not getting vitamin D 
> supplementation.  Most likely this is true of 20 year olds as well.  

No.  According to my review of the literature, in the tropics and
during the summer months above 36 deg latitude it is trivial to get
your needed vitamin D if you're frolicing in a bathing suit.  For
example (from http://www.ajcn.org/cgi/content/full/80/6/1678S):

    "Men and women in bathing suits who were exposed to a 1-MED 
    dose of UVB radiation exhibited increases in blood concentrations 
    of vitamin D that were equivalent to those observed with doses of 
    10 000-20 000 IU of vitamin D"

In other words, with the sun high in the sky, in a bathing suit,
15 minutes of sun should be plenty.

Also, from the paleo perspective it simply makes evolutionary sense.
Only when humans moved far enough north that sun exposure started
becoming a problem did their skin turn white... if sunlight wasn't
enough, Africans would have lighter skin.

> Most of us don't have the time or the sunlight to spend the day 
> frolicking for our rays, or spending the day out in the sunlight hunter 
> gathering for our daily nutrition.

Not even 15 minutes?  This is a paleo list... if you aren't willing
to change your lifestyle a bit for natural health, what are you
doing here?

> Have you checked your vitamin D levels?  A study in Hawaii found that 
> life guards that spend a lot of their time in the sun were deficient 50% 
> of the time in vitamin D.

Dunno about that study (references?), but I wouldn't be surprised
if a bad diet also interferes with your Vit D production.  

> For your average run-of-the-mill outdoor 
> person (which most people are not) sunlight will on average never be 
> enough to get sufficient vitamin D, even in the summer time.

Again, that doesn't make evolutionary sense.
 
> Again, have you checked your vitamin D levels?

No, but I'll try to.  I live in a tropical backwater, so it could
be a bit difficult to find a lab that will do that, but if I can
I will and will report back here.

:j

P.S.: I also don't have much access to supplements, and although
I can get Vit D at the local Pharmacy, it's expensive as hell.  I 
used to take lots of supplements, but I've gone to nearly none,
and with diet and lifestyle changes my health and physical 
condition is better than ever, and that's even though the humid
tropics can be pretty stressful on health (bacteria and fungi 
breed much faster, anything spoils fast, lots of insect
transmitted diseases, water is rarely clean, etc.)