Basically, our problem is just like TMAU. It's the same thing but with other type of food (methionine and cysteine from meat and sulphure from other sources) and other types of bad bacteria + liver enzymes do not convert well smelly bacterial byproducts to odorless.
Why they do not convert well?
1 - too many byproducts from too many bad bacteria ( I guess sulphure reducing bacteria) and liver enzymes can't convert all of the junk
2 - lack of liver enzymes which convert all those junk
3 - problems with fmo3 or similar gene which encodes enzymes or something
4 - digestion problems which is a starter for all of those stuff above (lack of stomach acid, lack of digestive enzymes, some irritants like gluten - which all cause other problems (sibo, candida, parasites and maybe heavy metal problems. Mercury and other metals screw enzyme production in liver and pancreas among other bad things)
Solutions (in theory):
1 - improve digestion (stomach acid, enzymes)
2 - reduce bad bacteria - good probiotic (not every probiotic works for everyone so test it) and fibers. Fibers (soluble + insoluble) are food for good bacterias so they are crucial to take
3 - some parasite and candida solution?
4 - improve liver function - as some of you knows, liver has 6 or 7 detox pathways. Minerals (in right form - chelate), b vitamins in coenzymated form (not folic acid but methylfoline, methylcobalmine for b12, p-5-p for b6 etc), some herbs which improve liver function etc
5 - taking stuff for possible inflammation - omega 3, ginger etc
6 - maybe include stuff which neutralize byproducts of bad bacteria right in the intestine like champex, activated carbon, chlorophyll
We all have similar problems, but some have bigger and some have smaller. Maybe some of us are full of bad bacteria and liver can't process all that junk. Others have some liver problems and not so much bad bacteria. Some of us have problems with gluten maybe, some with not having enough digestion enzymes, lack of stomach acid, parasites etc.
The thing is - do not just buy one supplement, take it for a month, then switch to second, fifth etc We need complete solution and we need to take it for weeks and maybe moths because we all are different.
All of this is a theory, but IMO - it's just like TMAU, but with other things, not choline.