one, that's BULLSH!T and two, since WHEN do inmates decide what they get to eat???
You might be interested in this document, which is a reply by prison staff to a complaint the Unabomber made about not getting his daily ration of milk (Federal prison in Florence, Colorado):
http://www.thesmokinggun.com/sites/default/files/imagecache/750x970/documents/tjkmilk2.gif