Mad dogs and ….

The Pharmacology of Vitamin D, Including Fortification Strategies
“During summer, we accumulate vitamin D3 and store it, so that supplies for vitamin D do not become completely depleted during the winter months. Within three days of a dose of vitamin D3, very little of the original vitamin D is detectable in plasma of rats (101) or humans (102). Most vitamin D entering the circulation appears to be excreted unmetabolized into the bile.[…]

If 30,000 years after entering northern Europe natural selection hasn’t changed this, as it easilly could, I have to wonder if the reason isn’t that the Vitamin D requrements are met, and then some, by North European sunshine.

“If one looks at the system of vitamin D metabolism in Figure 2 from the perspective of a system
designed to control something, it becomes clear that this is a system better designed to cope with an abundance of supply, not a lack of it. The flow of vitamin D toward 25(OH)D is remarkably inefficient, with most bypassing
it. Furthermore, there is no way to correct for deficiency of vitamin D, other than to redirect utilization of 25(OH)D toward 1,25(OH)2D production, which is the pathway most acutely important for life. That is, when supplies of
vitamin D are severely restricted, its metabolism is directed only toward the maintenance of calcium
homeostasis. To expand on the point that the system of vitamin D metabolism is effectively designed for adjusting for higher inputs, not lower inputs, I offer the example of an air-conditioner system. Air conditioners are designed to compensate for excessive heat, but they are a useless way to compensate for a cold environment.”

This points towards a natural homeostasis of vitamin D synthesis and storage in northern Europe that has not modified from the one evolved in Africa because it’s still dealing with an excess.

Trevor Marshall
“It is thus very difficult to find a population which can be studied in order to ascertain what the level of natural metabolic homeostasis for 25-D might actually be. These studies show a wide variation in levels of 25-D being generated by populations whose diets have probably not yet
been significantly altered by â??The Sunshine Vitamin,â?? indicating that the unsupplemented metabolic homeostasis is probably in the range 23â??60 nmol/L, and that it falls with advancing age.”

“When researchers went to an Italian nursing home, they found that 99 of 104 residents had no detectable vitamin D in their blood,”
(Bad news for these people ?)

All of the 104 resident were over 98 years old!
I hate to think how old they would have lived to if they’d kept their vitamin D levels ‘normal’.

This is one of the few posts I’ve done where I was able to string together more than 3 or 4 words. If you’re interested in what it’s like to live with it – then here you go .
http://car54.wordpress.com/2008/10/23/i-have-multiple-sclerosis/

However, the researchers believe that in people who carry the variant, a lack of vitamin D during early life might impair the ability of the thymus to delete these T cells, which then go on to attack the body, leading to a loss of myelin on the nerve fibres.

At first blush, that would also suggest an influence on other autoimmune disorders. (Not that I know a damn thing about the matter; I could easily be FOS.)

Assuming that the notion is not facially silly to anyone with a clue, it would be a relatively easy cross-check.