Dear Dr. Blonz: What are your thoughts about the use of oregano oil as a dietary supplement? One of my flight attendant colleagues uses it every day and has good feelings about it, although she could not provide any specifics.

— U.A., Washington, D.C.

Dear U.A.: Oregano, native to the Mediterranean area, is a culinary seasoning cultivated where different soils can lend unique characteristics to this flavorful herb. Like other plants growing amid the oxidizing rays of the sun and other assaults of nature, oregano evolved to produce its own unique cadre of protective substances that work together to help the plant survive and reproduce. We benefit from having a variety of whole foods in our daily diet to have a range of beneficial substances from different plants working on our behalf.

Oregano’s flavors and substances can be found in an essential oil extract, but is there any evidence that taking it as a dietary supplement will provide extra benefits for us? And how much would you need to take to get any benefit? I checked the research for oregano and one of its key compounds known as carvacrol, but found no clinical evidence — studies done with humans — to support conclusions of relevance to our health. There were some test tube (in vitro) and animal studies, but none with people, which is the essential element for making health claims. What is not in doubt is oregano’s ability to add wonderful flavors to foods we enjoy.

Pharmacological development is an evolving field, and many modern medications are based on naturally occurring substances. The key is fully understanding the risks and limits or their effects when moved from the plant context where they evolved to the human body with its complex biochemistry. This is where clinical research is essential — especially as there can be interactions with existing health conditions and medications.

Commercial enterprises — many on social media — seek ways to tout, market and cash in on novel substances before things are put to the test to verify efficacy, establish dosing and identify side effects and interactions with other substances and medications. These are critical elements, so always be wary before the evidence is there. For more on oregano’s botany, history, uses and medication interactions, see b.link/48d9upx. And don’t ignore the great variety of healthy whole foods already on the market.

Kensington resident Ed Blonz has a PhD in nutrition from UC Davis. Email him at cctimes@blonz.com.