For DMT to work orally, the addition of something referred to as a monoamine
oxidase inhibitor (MAOI) is required. MAOIs such as harmine inhibit the
production of the stomach enzyme and this allows orally ingested DMT to become
effective.
Naturally occurring MAOIs in combination with naturally occurring DMT have a
tradition of use in native South American cultures. Here the resultant
brew is most famously referred to as ayahuasca (other names include yage and
caapi)
The classic plant sources for MAOIs and DMT in ayahuasca include the Amazonian
vine Banisteriopsis caapi (which contains the MAOI harmine) and Psychotria
viridis (containing DMT).
Other plants can be used, for example, Syrian rue (Peganum harmala), as a source
of harmine.
Syrian Rue has no history of traditional usage; in fact the plant is not
originally native to South America.
In such cases, where at least one of the principle admixtures is a variant
like this, the brew is more properly referred to as an ayahuasca analogue.
Among
Ayahuasquera ~ Terence McKenna's account of an
Amazonian adventure