Re: Nutrition and the hoof
All new growth in the sole and frog are going to be inside, so what would be visible is an increase in the sole depth. The frog should gradually toughen up and become more substantial. It will likely shed parts that are currently ratty looking, exposing healthier material underneath. How fast the process goes is highly individual as there are so many factors determining this: where the individual starts from; genetics; diet; mechanics; any underlying disease processes that are contributing. You can start to see positive changes in weeks - some of which may be small or they may be eye-openingly obvious. Generally, the foot prioritizes fixing the most destabilized, thinnest portions first, rather than everything being fixed at the same rate. This may mean that parts of the sole get thicker faster than other parts, leading to a somewhat lumpy appearance. DO NOT remove the higher areas just because they are higher as that defeats the building process.
In a healthy foot, you are generally looking for 3/4" (1.87cm) calloused sole depth at the apex of the frog and 1" (2.5cm) at the deepest part of the collateral grooves toward the back of the foot. This can vary a bit but are safe assumptions to start off with. It also matters whether you are dealing with calloused sole or just newly grown sole, as calloused sole takes a lot longer to form than just adding the overall depth. Calloused sole is much more compacted, more dense material that requires time to form. It is much more protective as well. See here for an in-depth discussion:
Jan 2005, RI