The Damar tantra is considered to be one of the source texts for the shivambu information, and while purported to be ancient, these texts are copies of reletivly recent additions to scripture and possible evan high minded considerations rather than direct lineage revelations since we have no ancient copies to use for evaluation.
There are slight and evan larger differences in the different available copies also, as there are in all texts from everywhere in the world which are considered by some to be advice and truth scriptures.
As we all know the delima in much belief system reiteration is that while some confusion arises thru inadverdant translation or transcription error, some feel led to change or modify aspects, to remove passages, so as to stay in keeping with some one particular understanding.
The delima of changing the information to fit our understanding vs changing our understanding to fit the available information.
The copy I use and appreciate, advises, no animal flesh, no greens, no grains, no dairy. This fits in well as working best w my personel experience also.
I originally learned about UT from the Thai forest monks, and u will find it in Thai religious literature similar to the already mentioned Hindu writings. I found no special dietary caveats from this source for this therapy.
While I find that Dr Thakur's modernized Shivambu text and Coens and Christie's works sharing about UT very valuable, the slightly different dietary choices I see as personel renditions from personel experience and I can give them only that much authoritative position in comparison to anyone's experience and choices. Keeping in mind what we know from chemical analysis of the fluid re food intake.
While it may be important to know that eating animal flesh and practicing ut can cause the dangerous buildup of Indoxal(sp), the other choices may not be as critical tho I find that for long term practice and in retreat/healing regimins especially , ripe fruit, only, works best ( while also being a personel mental and emotional test to see how controlled we are or not regarding oral gratification)