Nosestretcher alert: Eating pizza is protective against norovirus

I subscribe to the notion that there’s no such thing as bad pizza. It’s hard to mess up cheese, sauce and some sort of meat or veg. Often the best has some herbs like oregano sprinkled on top as well.

I’m not sure it’s a magical food though.

There’s been a lot of coverage to suggest it is magical, all in reference to a recent paper by Gilling and colleagues in the Journal of Applied Microbiology detailing the effects of oregano oil on norovirus. Some of the stories are particularly glowing:
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University of Arizona researchers found an ingredient in pizza that could prevent suffering from winter vomiting disease, norovirus.

and

If you feel guilty after eating a slice of pizza, a new study may help you feel better. An ingredient in oregano has been found to boost immunity, at least in laboratory cells.

The authors of the cited study use murine norovirus (MNV) as a surrogate to human norovirus HuNV. There is some debate in the virology community as to whether MNV is a good surrogate (especially since isopropyl and ethanol shows a decent level of inactivation against MNV, which is not seen with HuNV). It’s not the same virus.

And I’m not sure about the practicality of throwing oregano oil (or it’s active ingredient carvacol) onto food contact surfaces or food.

The authors state,

In the present study, oregano oil and its primary active component, carvacrol, were evaluated for their antiviral activity against MNV as a surrogate for NoV for their use in potential applications such as surface disinfection (including use in clinical settings) or food sanitization. As such, a discussion of quantitative log10 reductions following various periods of exposure is relevant. Oregano oil and carvacrol both significantly reduced MNV titres within 15 min of exposure (0.95-log10 and ≥1.03-log10, respectively). Despite this, the infectivity of MNV treated with oregano oil remained stable over time (1.07-log10 reduction in infectivity within 24 h of exposure), whereas carvacrol was far more effective, producing 387-log10 reductions in MNV within as little as 1 h of exposure.

Exposing a virus that sort of acts like human norovirus, but but sort of doesn’t, to carvacrol (a component of oregano oil), for 15 min you can get get a 1-log reduction infectivity after 15 min. A bit of a stretch from pizza protects against norovirus (above, exactly as shown, courtesy of Gordon Hayburn).

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About Ben Chapman

Dr. Ben Chapman is an associate professor and food safety extension specialist at North Carolina State University. As a teenager, a Saturday afternoon viewing of the classic cable movie, Outbreak, sparked his interest in pathogens and public health. With the goal of less foodborne illness, his group designs, implements, and evaluates food safety strategies, messages, and media from farm-to-fork. Through reality-based research, Chapman investigates behaviors and creates interventions aimed at amateur and professional food handlers, managers, and organizational decision-makers; the gate keepers of safe food. Ben co-hosts a biweekly podcast called Food Safety Talk and tries to further engage folks online through Instagram, Twitter, Facebook, YouTube and, maybe not surprisingly, Pinterest. Follow on Twitter @benjaminchapman.