>For 100 grams:
>sunflower seed kernels, dried       354
>sunflower seed kernels, dry roasted 129
>i.e. roasting destroys 100*(354-129)/354 = 64 per cent of the magnesium.

 But heat does'nt destroy magnesium.  Perhaps its the bio-availability of it
that's destroyed? If so, how do they know?

Lynton