Now while it is certainly true that many essential oils are used in the Food Industry as a flavoring ingredient the amounts used are in very small parts per million. For instance, in the Encyclopedia of Common Natural Ingredients used in Food, Drugs, and Cosmetics, 2nd Edition, Albert Y Leung and Steven Foster say:
Spearmint oil and peppermint oil (usually rectified) are extensively used in flavoring chewing gums, candies, and chocolates as well as in most other food products, including alcoholic (liqueurs, etc) and nonalcoholic beverages, frozen dairy desserts, baked goods, gelatins and puddings, processed fruits, and sweet wauces. The highest average maximum use levels reported are 0.104% for peppermint oil in candy and about 0.132% (1318 ppm) for spearmint oil in baked goods.
This means that even in the highest dosage 0.104% for peppermint in candy, very, very little essential oil is actually consumed at any one time. Compared to that, consuming just 1 drop of essential oil of peppermint is almost a thousand times higher.
In their book, 2nd Edition of Essential Oil Safety, A Guide for Health Care Professionals, Robert Tisserand and Rodney Young point out :
Much larger amounts can be administered [through Oral administration] than by other routes, so great care must be exercised if prescribing in this way.
One disadvantage of oral dosing with essential oils is that some of the constituents might irritate the gastrointestinal mucosa, which is generally more sensitive to insult than skin. Since irritation is concentration-dependent, it is important that the essential oil is efficiently dispersed or dissolved in an appropriate vehicle before being swallowed.
Oral administration always carries the potential for inducing nausea and vomiting, and the presence of food has unpredictable effects on absorption into the bloodstream. Digestive enzymes can break down some types of essential oil constituents, for example esters may be hydrolyzed in the stomach. After absorption from almost all regions of the gastrointestinal tract, most substances pass directly to the liver, where a significant proportion is deactivated in first-pass metabolism but some, paradoxically, are made more toxic.
Virtually all recorded cases of serious poisoning with essential oils have occurred after the ingestion of large amounts of essential oil.
With oral administration there is a greater risk of overdose, of gastric irritation, and of interactions with medications. Therefore only practitioners who are qualified to diagnose, trained to weigh risks against benefits, and have a knowledge of essential oil pharmacology should prescribe essential oils for oral administration.
In my opinion, this certainly gives us some food for thought when it comes to the question of taking essential oils orally. Obviously there is a time and place for everything, but using essential oils orally is something, in my opinion, that one would reserve for very serious conditions and then only under the guidance of a primary medical care practitioner.
Essential oils are extremely effective in very small doses, so why would we overload our systems with more than we need?