I haven't tried O.E.P. but I've tried similar stuff:
Cellfood
Master's Miracle Nutralizer
Neither had any effect on me whatsoever.
I also gave Cellfood to my brother in law to try, and he didn't feel any effect either.
I also once saw a post by someone who had found a site which rated various oxygen supplements ranging from Willard Water to Cellfood. And Cellfood was rated at the TOP of the list of many such items.
Yet... Cellfood did nothing for me, or my brother in law.