QUESTION: Are you familiar with the other systems of metabolic typing? By this I mean the acid-base balance system and others (fast/slow oxidizer, etc.) Can they be used to improve the accuracy of the your own theories?
ANSWER: There are several other systems of 'biotyping' in the popular diet literature, including those that you have mentioned, the doshas of Ayurveda, and a few others.
Although I cannot prove that these other systems are without some value, it is a fact that none of these systems of 'metabolic typing' are represented in the scientific literature. Not a single study exists that would serve as a logical starting point from which to draw conclusions about something as important as an individual's lifestyle.
Not looking so good for metabolic typing research.
In contrast, we could search the medical databases, such as PubMed, OMIN or Ovid and find thousands of scientific articles on the phenotypic aspects of the blood group and secretor subtypes. In addition, the blood groups have had their genetic basis well determined, as well as many disease susceptibilities. In contrast, a search of the medical databases using keywords such as "fast oxidizer" or "blood acid pH" or "metabolic typing" does not yield a single scientific study, and no gene has ever been identified as a source of these distinctions (an important distinction, since without a genetic basis for transference to offspring, you have nothing better than a collection of random occurrences.)
Same for fast-oxidizer research.
Blood types are much more useful. Blood type virtually never alters over your lifespan, the testing is quite easy, inexpensive and the determinations virtually fail-safe.
On the other hand, the most stringent string search for studies on ABO blood group yield over 10,000 articles.
There are even over 1000 published studies on secretor status.
Finally, one should be wary of proponents of metabolic typing, including doctors, who disparage the significance of the blood groups. Many doctors offer metabolic typing as part of their own marketable services, and the large universe of blood type dieters offers an attractive potential market. On the other hand, recommending that a patient visit a local blood bank and library is not as likely to help pay the bills at the end of the month.