Just to note, as Ive said this many times. I do not agree with the "traditional dieta" for myself (not saying others shouldnt follow), and I think there are more historical/contextual reasons for it than actual spiritual/pharmacological reasons.
I think when the indigenous people started interacting with the modern western world, they suddenly had big access to things such as refined sugar and salt, and other foods for which they were not prepared for (maybe lacking enzymes too, etc?). Then, when they drank aya, they probably would have gotten the message: "hey you, stop eating all that crap". And for probably many shamans/indigenous people/mestizos this was indeed so. Now, this, over the years, gets passed on as an inflexible rule, when in fact it made sense to one specific context.
I think translating to the western world, a lot of people eat really bad. Lets face it, most westerner's diet is CRAP. It is full of refined sugars, industrialized products, conservatives, excess meat with all sorts of antibiotic and whatnot, etc etc. So of course it also makes sense that some of these people would benefit from suddenly changing their diet for a few days to "purify" themselves, to get some insight on their own habbits. Then these people come back and say how great the diet is.
BUT.. What is the actual message that ayahuasca is giving? IMHO, at least for me, the point is NOT to stop eating food X Y or Z when taking aya, but to EAT HEALTHY... Not just before and just after aya, but ALWAYS. I have completely changed my diet since I started taking psychedelics in general but specially ayahuasca.
I have tried different kinds of "dietas" when taking ayahuasca, and feel there's nothing there for me, it didnt change anything for my experiences. I feel that what did make the trips significantly better is just eating good in daily life. Appart from that, whether its aya or mushrooms or whatever, I always try to eat specially light during the tripping day, regardless if it has salt or cheese or whatever, all these things can be there, but excess of anything is bad, even the "allowed" foods IMO (like for example refined pasta would be ok in some dietas if it has no salt (majapanix once mentioned this too) , doesnt matter if you eat 3 plates full, and IMO thats really NOT something one should eat before tripping)
Lastly, dietas are arbitrary constructs, they are NOT universal. For example in some dietas you could NEVER have sex or alcohol. But what about the Shuar which even have a ritual where they drink fermented alcoholic drinks together with ayahuasca (and have sex too IIRC). Im not sure if it was also the shuar but there was one tribe that mixed freebased coca leafs with ayahuasca, while to other tribes that would be big no-no.
Follow what YOU think is right for YOU, but dont tell others what they should or should not eat, unless its specifically related to some pharmacological danger, which in the case of tyramine and MAO-A inhibitors, is not the case. At least thats how I feel.