Dear Dr. Roach: Many of my friends assert that the use of essential oils “supports” their immune system and reduces their risk of getting sick. They diffuse them into the air at home, add them to water or tea and apply them to the soles of their feet. Are there studies to back up these claims? — K.M.
Answer: There are studies that show that, in some cases, essential oils stimulate some of the body’s immune cells. Blood levels of immunoglobulins, cytokines and other molecules that indicate a robust immune response can increase with exposure to essential oils.
However, no studies show what I would want to see before recommending their use in general, which is that people who use essential oils have less infections or less disease than people who don’t. In an ideal world, it would be great to know who should use what essential oils, and under what conditions. Many sources provide such advice, oftentimes conflicting, but none is supported by the kind of evidence I would accept.