Baker's yeast from the packet is live, and therefore not used as a nutritional supplement (it can cause gastrointestinal distress). Once baked, such as in bread, it's as dead as a Chicken McNugget. Same for heat-dried brewer's yeast, which IS used as a nutritional supp. (I believe they're the same strain of yeast, believe it or not.) Any yeast which has been pasteurized, typically through heating, cannot reactivate in the gut, ferment and cause problems -- it's plain ol' dead.
The significance and ramifications of consuming incidental yeast (whether dead or viable), such as through wine, beer, vinegar, bread, mushrooms, ketchup, etc. is in contention. Most say they can cause problems such as allergic reactions in those with candida overgrowth. At least some experts suggest this claim is overblown. Probably the safest precaution would be to avoid 'em in quantity, although modest amounts of condiments like ketchup, vinegar, etc. aren't likely to be an issue.