His information is a little unclear here. He refers to an "acid balance diet". One would presume that an "acid balance diet" would lead to a condition of acidosis. It seems that that is too simplistic a view, that's like saying "fat makes you fat".
So, with proper mineral and vitamin uptake, the body has the tools that it needs to maintain proper pH, no matter the source of those vitamins & minerals? Once again whole food sources, of course.
BTW, high vitamin butter(activator x)/fish oil blends are available through links on the Weston Price site...