I'm pretty sure harmine and harmaline are found in coffee too. I thought it was common knowledge but all I found were two papers so maybe not.

1. https://www.sciencedirect.com/science/article/abs/pii/S00243...

2. https://www.sciencedirect.com/science/article/abs/pii/S03088...

They are found in both, in high concentrations. Tobacco smoke and coffee are the two most significant sources of Harmala alkaloids in the human diet. (Source: T. Herraiz)

Well, they are found in everything, meat, soy sauce, beer, right? Tobacco is a much more common source. By the logic of your previous argument, eating yakisoba could lead to dementia.

Interestingly, your source’s paper on this says that coffee protects against brain disease:

> epidemiological studies have consistently shown that coffee drinkers have an apparently lower incidence of Parkinson's disease (PD), suggesting that coffee might somehow act as a purported neuroprotectant

https://pubmed.ncbi.nlm.nih.gov/16139309/

Either way, I’m not particularly interested in this subject, the point is that making wild medical claims without sources in an online forum is best avoided.

They are indeed found in many products, but the key is the exact nature of the specific substances. Do they inhibit MAO-A, MAO-B, or both? Are they irreversible or reversible inhibitors? Do they do other things like cause neurotoxicity? The Harmala family has dozens of compounds, some good for you (for example MAO-B inhibitors indeed prevent PD, because MAO-B inhibitors are used to treat it) and some bad, like some beta-carbolines that are indeed neurotoxic.

Again, the total amounts are what matters. It’s much easier to take in too much MAOIs from tobacco and coffee than by eating meat.

Something seeming to protect against one specific disorder does not mean that it protects against all diseases.