It's rather about what genes are active or not, not "gene change". Genes don't change, unless it's some positive/preferable mutation, if negative then the body will correct it if it has what it needs. Genes that have no apparent need at some point go to "sleep". If some genes are never stimulated in the first place (a child since birth learns to live in a limited box, as it is more than common in our "modern world", which translates into no need of most of the individual's inherent potential, and then the critical learning point passes) then it can be extremely difficult later on as an adult to turn the once "useless" genes on even in the presence of some conditions they should correspond. Turning them on in such a circumstance would require a rather open and aware and perceptive and calm mind, and persistent "training" and looking into oneself.
There are other influences than food as well that affect which genes end up active or not.