Not necessarily, you'd be surprised just how hardy both the yeast granules (really sporulated yeast) and ADH can be. I've actually done some research in this area (for unrelated reasons) but here's the a "must read" paper from 1975 if you're curious: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1165444/
"were studied in the pH range 4.9--9.9 at 25 degrees C and in the temperature range 14.8--43.5 degrees C at pH 7.05."
Forgive me if I am missing something obvious, but isn't that outside the range of a typical stomach's pH range? If so, how does this study relate to the conditions inside a stomach?
Im basing these questions on what I saw in that skeptic.exchange link posted above, again im a total layman.
Stomach pH ranges between 1-5, what you eat contributes significantly to the variance in pH. The "active" yeast that's sold is actually the inactive spore (not actively budding) and low pH environments promote staying inactive. ADH is produced by metabolically active yeast, which theoretically would be yeast that reaches your intestines (indeed, we have "native" yeast in our intestinal tract).
Whether or not yeast would make it that far and then being to bud and produce ADH again, I couldn't really say. I never looked at human-ingestion of colonies.
ADH itself can be denatured in low pH environments but will renature and self-fold into an active tertiary structure when brought back to neutral/slightly basic pH.
