MAO stands for Monoamine Oxidase: two enzymes, MAO-A and MAO-B, which are naturally found within the human gastrointestinal tract. The MAO barriers are a safety mechanism in our body that protects us a range of mildly dangerous foods. The DMT found in the plants like P. Vidiris and M. Hostilis are inactive when ingested due to the MAO enzymes in our body.
There are two groups of MAO inhibitors: irreversible and and reversible (also called RIMA - Reversible Inhibitor of Monoamine Oxidase). In Ayahuasca you can only find RIMA. The main difference between them is the duration of the effect. MAOI effect can last 1 to 2 weeks after ingestion (like synthetic MAOI used for depression treatments) while RIMA effects only last a few hours after ingestion.
Banisteriopsis caapi and Peganum harmala contain Harmine and Harmaline, an alkaloid that stops the action of the MAO enzyme, allowing the DMT to be effective: they are RIMA. Also, apart from a shorter effect (maybe up to 24 hours maximum), the RIMA mechanism of Ayahuasca shows a more selective inhibition process than its synthetic counterparts acting only on MAO-A enzymes.
The dangers in using MAOI comes from the fact that the Tyramine can be freely absorbed in amounts larger than our body can handle. When the Tyramine is absorbed by our body it will displace the adrenaline and pumping it into the blood stream making way for strong headaches, heavy sweating, dilated pupils, heart palpitations, increased blood pressure.
However, the RIMA found in Ayuahasca brew allows the body to continue to regulate it in a certain degree, however it is still wise to pay attention to what you eat and take (prescription drugs or other drugs).
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