Some literature, mostly animal studies, tout the anti-cancer properties of phytic acid: http://jn.nutrition.org/content/133/11/3778S.long.
While many studies say ip6 from phytic acid can't be digested, this says the opposite:
"Contrary to the dogma and skepticism at that time, we showed that IP6 is taken up by malignant cells (21) and that orally administered IP6 can reach target tumor tissue distant from the gastrointestinal tract (22). Because of the highly charged nature of IP6, it was a common misconception that it could not be transported into the cells."
Some correlation between high iron and colon cancer:
Iron chelation therapy from phytic acid can help with excess of certain mineral overloads.
Here's my take. The verdict is still out on phytic acid, but depending on your needs, you may be better avoiding it-if you have bone loss, or low iron for instance. However, if you have high iron, maybe you might be okay with it in some amounts. I think ultimately it will come down to ratios of specific minerals. Also, if you are eating nuts on a paleo diet, you will be consuming a high amount of phytic acid.
Mat Lalonde eat black beans and I think Travis on this site says he might be OK with beans/legumes as long as they are eaten separately from other foods like meats.