Vitamin D

On the last post I mentioned the Kitavans and their tendency to eat fish as their primary source of protein. Fish comes bundled with omega three fatty acids and I would suggest that this is a major contributor to their overall health.

The other highly relevant substance for human health is vitamin D. This is not really a food related vitamin or even a vitamin at all, as we make it ourelves. I think it's probably impossible to improve on Vieth's early summary except to say every paper published on vitamin D shows that it is critical to avoiding heart disease, cancer, multiple autoimmune diseases plus type 2 diabetes. And anything else you care to mention I guess.

How much D is needed for health? Vieth's abstract sums it up in these terms:

"Except in those with conditions causing hypersensitivity, there is no evidence of adverse effects with serum 25(OH)D concentrations <140 nmol/L, which require a total vitamin D supply of 250 µg (10000 IU)/d to attain. Published cases of vitamin D toxicity with hypercalcemia, for which the 25(OH)D concentration and vitamin D dose are known, all involve intake of 1000 µg (40000 IU)/d. Because vitamin D is potentially toxic, intake of >25 µg (1000 IU)/d has been avoided even though the weight of evidence shows that the currently accepted, no observed adverse effect limit of 50 µg (2000 IU)/d is too low by at least 5-fold."

So Vieth is pushing for 10,000 iu/d. Six egg yolks provide about a third of the Fitday RDA (recently increased to 10 µg or 400 iu). Half an hour's sun bathing provides Vieth amounts. But even when the sun does shine in January there is no UVB in the UK. So 10,000 iu of oil based D3 it is during the Winter.

I was curious as the the probable vitamin D status of the Kitava natives studied by Lindeberg. They maintain their insulin sensitivity throughout their lives and vitamin D is crucial for this. Lindeberg didn't measure D3, so I've had to have a guess. Kitava is just off of the equator. My guess is that there is probably about 12 hours of sunshine per day many days of the year. I wondered how pigmented the Kitavans were and how much clothing they wore. These are primary determinants of vitamin D3 synthesis.

Putting "Kitava" in to a google image search brought this up as the first hit. Humans are mammals. Please do not click on the following link if you are offended by the direct proof of this. It's to do with feeding babies.

Kitava native

I would guestimate 10,000 iu/d D3, most days of her life.

That's my Winter supplement sorted out. Summer time I'd opt for the Kitava solution.

Peter