Dear Doctor: Can olive oil be used topically to aid healing?
Dear Reader: Olive oil has been used since ancient times as a cosmetic and to aid skin healing. The ancient Egyptians used it as an anti-wrinkle potion; the Romans used it as a moisturizer after bathing. To this day, olive oil is used widely in many countries to treat and prevent multiple skin conditions.
Now let's look at the evidence.
The purported benefit of olive oil may come from its fatty acid composition, predominantly oleic acid, but also palmitic acid and linoleic acid. These fatty acids have been thought to have both anti-fungal and anti-bacterial properties.
Oleic acid, a monounsaturated fat, has been shown to penetrate the upper layers of skin, where it permeates between the cells -- seeming to suggest that it's an effective moisturizer. Anecdotal evidence might seem to bear that out, but note that oleic acid has been found to actually increase water loss across the epidermis, countering the notion that it can help lock in the skin's moisture.
In a 2013 study published in the journal Pediatric Dermatology, researchers studied volunteers who applied six drops of olive oil to their forearm twice daily for five weeks. They found that the skin treated with olive oil not only lost water, it also experienced a reduction in skin thickness and integrity, and in some people caused a local reaction. The authors surmised that olive oil's disruption of the skin may allow for penetration of allergens and increased inflammation of the skin's layers.
Some people use olive oil in an attempt to mitigate stretch marks induced by pregnancy. The evidence for that is sketchy as well. In a 2012 study published in Complementary Therapies in Medicine, 50 women who were 18 to 20 weeks pregnant applied olive oil twice daily to their abdominal skin, massaging it in gently each time, keeping this practice up until they had delivered their baby. A control group of 50 women applied nothing to their abdominal skin. Although researchers did find some decrease in severe stretch marks among those who used olive oil topically, they found no overall significant difference in stretch marks between women who used olive oil and those who didn't.
One place where olive oil may hold potential is in its treatment of diabetic foot ulcers. A 2015 study published in the Journal of Diabetes and Metabolic Disorders showed a significant improvement of healing and shrinking of ulcers with use of olive oil among people with grade 1 or grade 2 diabetic ulcers (the least serious of the grades, which progress to grade 5). Complete ulcer healing occurred after 4 weeks in 73.3 percent of those who had olive oil placed over the ulcer versus 13.3 percent who didn't. This healing may be related to olive oil's potential to dry the lesion, which is linked to its propensity to remove water from the skin.
As for other skin conditions, some case reports have suggested that olive oil may reduce acne and symptoms of impetigo, but no controlled studies have been done.
So the evidence for olive oil on its own as a topical agent is not convincing. Further, it may even cause skin irritation, so I wouldn't recommend it as a moisturizer, especially for infants. But because of olive oil's ability to penetrate the skin, it could potentially be helpful in combination with another agent. As for its potential in healing skin ulcerations in the lower legs and feet, further study is needed.
(Send your questions to email@example.com, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)