Re: the China study (of which all I know is what I just read on Wikipedia).
I don't want to tell you what to believe, but for the record the correct scientific measure for morbidity is "all-cause" mortality. For example, suppose I say to you that eating M&Ms halves your chance of death from liver cancer. Your response should be "What are my overall chances of dying"? For example, while it halves your chance of death from liver cancer, maybe it doubles your chance of death from pancreatic cancer. It is not enough to say that diet X "lowers the instance of Western diseases" - the realy question is, does it genuinely stop you from dying. Of anything.
Once you have shown that an environmental factor is indeed correlated with a reduction in all-cause mortality, then the next thing to do is try to prove causation (since we all know correlation is not causation). For example if you told me that the average life expectancy in China is 100 and in the west it is 70, I would say "so if you parachute a bunch of Westerners in China, would they live to be 100?". It may be that Caucasians, exposed to the "Western Diet" for millenia, are actually well adapted to it.
These are very hard questions to answer to a high level of scientific confidence. I also don't like the implication, as reported in Wikipedia, that if lots of animal protein is bad for you, 0 is bound to be better. Every single substance known to man has a poisonous dose and a safe dose. There's a safe dose for arsenic. The burden of proof to say that 0 of something is meaningfully safest is very high.
I'll give you a well-researched example. Mercury is a neurotoxin. In certain quantities it causes terrible mental decline. There is mercury in fish, mainly in the fish that are high up the food chain (eg. swordfish, marlin, the big tunas etc). So, in the US it is standard to advise pregnant women not to eat fish, so as to avoid exposing the foetus to significant levels of mercury, which from experience with industrial workers can cause low IQ levels and other problems.
You would think that is cut and dry? It turns out that if you go and study Pacific Islander populations where all they eat (three meals, 7 days a week) is fish, then there's nothing wrong with their kids.
Why? I don't know. The point is that even with one single chemical compound and one well-known effect, it is really hard to understand what goes on inside the body. So doing so when you have something as complicated as nutrition on one hand, and longevity on the other, is really really hard to do, and in principle I distrust anybody who claims to have a simple answer.
I mention all this because you seem to have good motives and say you are building a business on this. I suggest you look a bit further than one or two best-seller books before you commit yourself.