MySQL Tuner OPTIMIZE and Defragmentation
Once you delete some rows from a table its data file could become fragmented and that table becomes unoptimized in terms of MySQL. If you really do frequently delete rows from those tables, you should not worry because this is the expected behavior. You don't need to do anything else.

OPTIMIZE TABLE is usually used to reclaim the unused space and to defragment the data file. Also you should know that MySQL locks the table during the time OPTIMIZE TABLE is running, which means that no one can run queries against that table and has to wait.