I'm curious too. My NUT isn't familiar with EOs so was no help. I'm sure gentle ones like lemon are fine. I take LLV, and the one for allergies daily. Today I feel a cold coming on so I'm taking 2 drops each of On Guard, Frankincense, melaleuca, oregano, and lemon in a gel cap every couple of hours. It seems to help the cold symptoms but I have to chase it with tums and I still get some reflux. For that reason I'll probably stick with external application for awhile after surgery (6/15/15). With all the studies being done on EOs, bariatrics seems to be an untapped area so far.