At a rough guess, about a third of the essential oils I use come from plants that also have culinary uses. There are the many spices and herbs, along with the citrus family.
However this does not mean that we can automatically use the essential oils in cooking because they are so concentrated. That said, the toothpaste industry probably uses more essential oil than aromatherapists do! Many convenience foods also contain essential oils though they are more likely to be called, “natural flavourings.”
One of the best ways to get the therapeutic effects of a plant, particularly the herbs and some spices is to use them in an infusion or tea. Chamomile is often used to help with indigestion. I sometimes make a tea using sage, lemon verbena, or lemon balm (Melissa) though usually just because I like the taste.
Or is it just because I like the taste? Perhaps I am following the wisdom of my body? Cows pastured on herb rich meadows will eat different herbs when they are pregnant from when they are suckling.
The same principle can be used for choosing essential oils for a treatment. I sometimes get clients to smell different oils to choose, especially when the ones I think likely to help their condition are not ones commonly known to those without specialist knowledge.
Returning to the kitchen, I occasionally use some of the citrus oils in making things like cheesecakes. Other than that I am much more likely to use the fresh herb and even with the citrus oils I more often than not will grate some zest into the mix rather than use an essential oil as I believe that this gives a better balance for the body rather than the concentrated aspects of the plant present in an essential oil.
Others attribute this to the, “life force” in the whole plant. I will leave it to the reader to decide whether they think the difference can be explained in terms of plant chemistry or if they believe there is something more esoteric at play here.