John Miller wrote:
> Another argument I've read is that grains contain high levels of phytates
> which block mineral absorbtion.  I also understand that both of these (phytate
> content, carbohydrate density) are problems with beans as well.  Can anyone
> verify?  Elaborate?

It's true that phytates block mineral absorption, and that whole grains and
beans are high in phytates (e.g. phytic acid). Soybeans are particularly high.

This is not an effect limited to non-paleo foods, however. Substances in a
range of vegetable foods do this. The next best known example is probably
the oxalic acid in spinach.

Fortunately, the mineral-binding effect is greatly reduced by ascorbic acid.
I read a study (don't have the reference on hand, I can get it if you really
want) that found that high vit. C levels in the diets of vegetarians could
more or less counteract the mineral-binding problem.