I've hardly ever used mint or thyme as supplements, but you can bet that any herb with culinary uses will be good for your digestion. I tried enteric coated peppermint gels one time for symptoms of irritable bowel syndrome, but it only seemed to make the diarrhea worse for me, I guess because it was killing off so much yeast so quickly. Thyme is often used for the respiratory tract, and often combined with fenugreek because the two work together synergistically to increase each other's expectorant properties.

Bee propolis is a natural supplement that can be found in most health food stores. It's a substance that the bees secrete and line their hive with to keep it sterile, despite the warm, moist conditions inside that would otherwise lead to overgrowth of bacteria and fungus. I've used it myself from time to time for my yeast overgrowth and it always results in lots of die-off symptoms, a sign that it's working. It has a very strong distinctive odor, but it's not too bad in capsule form.