The more I learn, the more I realize the best diet for old folks (and pretty much all folks) is heavily based on high quality, pastured eggs, raw A2 milk, and grass fed beef & steak (I get my creatine...
I would just add that in seasons when there is little grass, seafood is a better choice. Not sure but in dry seasons, feed is supplemented with grain and here it's allowed to be called ' grass fed'. If there is yellowing lawn in the yard and the lawn mowing service less regularly....it's the sign