Anything swallowed passes through the gut wall and the liver before it reaches general circulation, and enzymes there can destroy much of it. That stage is first-pass metabolism. A 1984 analysis concluded that DMT is inactive by mouth because MAO in the gut and other internal organs breaks it down (McKenna, Towers and Abbott, 198490003-5)).
Direct human evidence came in 2015. In a study of six people, swallowed DMT produced no psychotropic effect, no unchanged DMT was recovered in urine, and 97% of what was recovered was the MAO product (Riba et al., 2015).
Ayahuasca gets around this. A double-blind study of 18 volunteers found only negligible blood levels of harmine, the main β-carboline, and concluded that it acts mainly in the gut and liver, where MAO inhibition “would suffice to prevent first-pass metabolism of DMT” (Riba et al., 2003). The same blocking changes how the body handles many medicines and foods, which is why such combinations carry real interaction risks. This is not medical advice.
Sources
- McKenna, Towers and Abbott, 1984, Journal of Ethnopharmacology
- Riba et al., 2015, Drug Testing and Analysis
- Riba et al., 2003, Journal of Pharmacology and Experimental Therapeutics: ayahuasca in humans
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