I'm no expert on the subject by any means but after some searching around I think I figured this out.
According to:
https://www.deepdyve.com...e-substitutes-8GhBQlgaICAnd:
http://www.ncbi.nlm.nih.gov/pubmed/17291006Most coffee seems to have very tiny amounts of harman and norharman in it that is produced mostly in the roasting process. We're talking 0.01% at absolute best by weight.
Conversely:
https://www.erowid.org/p.../syrian_rue_basics.shtmlTold me that rue seeds are anywhere from 2-7% weight by volume of harman, norharman, harmalol, and tetrahydroharmine. If you can get rue it's definitely cheap compared to many alternatives. From my estimates you'd be broke by the time you bought enough coffee to have a respectable amount of MAOIs.
That's not to say it's impossible to do. Just not a worthy investment of time and money. Enjoy a cup of coffee instead.
Edit:
I read some more. According to:
https://www.erowid.org/l...a/aya_sec1_dosages.shtmlIt says that 120mg is the minimum amount of harmine base to activate oral dmt.
So for coffee at 0.01% you'd need a around 1000 grams, over 2 pounds, of coffee for a single minimum dose.