Researchers (D.H.Gilling et al.) recently investigated and published an article online in the Journal of Applied Microbiology about the antiviral efficacy of oregano oil. The active antiviral ingredient is carvacrol, the substance that gives oregano its distinctive smell. Carvacrol is active against a murine norovirus – a close relative of human norovirus. We all are aware that norovirus is the cause of most diarrheal outbreaks on cruise ships. This is in part due to its highly infectious nature – a miniscule inoculum can cause infection. (I refer you back to a June 19, 2012, post in this blog.)

Exposure to either oregano oil or carvacrol itself produced significant reductions in virus infectivity within minutes, approximately 1 log₁₀ for oregano oil and 3.87 log₁₀ for carvacrol. They did this by disrupting the viral capsid and its subsequent RNA production.

Before you advise your patients about this study, which could cause a run on oregano (why does this remind me of the 1960s?), oregano oil, or carvacrol, the catch is that it does not help in the gut. No, it only helps as a surface disinfectant. And not a very good one at that. By way of comparison, bleach is 100-fold more effective as a surface disinfectant. But you cannot use bleach on your food and bleach has that chlorine smell (sometimes with added lemon or springtime floral – so chlorine floral).

A number of questions remain:

Do Italians get less norovirus? How about Italian restaurants?

What about the Simon and Garfunkel quartet of herbs?

How was Oregon named?

Marshall Kubota, MD