Re: Re: Optimal vitamin A/D ratio

March 10, 2009

>

> > Well, just because a molecule is fat-soluble and has a trans double bond

> > doesn't make it a trans fatty acid. The various forms of vitamin A are

> > lipids with many trans double bonds but are not fatty acids (they are

> > technically terpenes, a class of hydrocarbons). The trans double bond

> isn't

> > bad per se.

>

> Neither are trans fatty acids bad per se (which is why we don't avoid

> butter). And, in fact, the body enzymatically makes trans fatty acids

> wherever it burns unsaturated fatty acids for energy during

> beta-oxidation.

>

Interesting!

> > Fascinating; I had thought that vitamin A status affected night vision

> far

> > before anything else, so it's interesting you see a clear difference in

> > adaptation to both bright light and dim light—or did you mean you only

> see

> > the difference when moving from bright to less-bright light?

>

> This is interesting indeed. However, Lana, is this what you meant by

> sensitivity to light? I was thinking of another phenomenon -- bright

> light being uncomfortable and especially anxiety-producing. However,

> I think this (and probably an above average need for vitamin A) is due

> to my incredibly light blue eyes, which let in a lot more blue light

> (which is toxic and anxiety-producing).

>

It is actually both. Bright light is painful, kind of like sound so loud it

" clips " the upper limit on a stereo. Prolonged contact with it does cause

anxiety for me too (much in the way excessively loud sound would). In terms

of night vision it impacts me more because of the bright lights (especially

headlights) than the dark itself - I can see just fine in the dark as long

as there are no sources of bright light. The light seems to pierce my head

so much more when it is dark out... and it makes it practically impossible

to differentiate between the shades of dark (what I have always been told

was night blindness). But generally I find the irritation/anxiety far less

annoying than the piercing pain.

-Lana

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