Brain Food and Bacteria

Summary

More or Less — “Brain Food and Bacteria”

BBC Radio 4 | Host: Ruth Alexander | Air Date: November 19, 2012

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Overview

This lively episode of More or Less investigates two quirky but serious statistical stories: the much-hyped claim that chocolate consumption is linked to Nobel Prize winnings, and the oft-cited (and misleading) idea that everyday surfaces are “as dirty as a toilet seat.” Host Ruth Alexander uses humor and science to separate statistical truth from myth, drawing on key expert voices.

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Main Topics and Discussion Points

1. Does Chocolate Make You Smarter? (00:13–04:46)

Summary

• The episode opens with eye-catching headlines suggesting a scientific link between chocolate consumption and increased intelligence, as measured by the number of Nobel laureates per country.
• Ruth Alexander interviews Professor Franz Micelli, whose study in the New England Journal of Medicine inspired these claims.

Key Discussion Points

• Origins of the Chocolate-Intelligence Hypothesis (00:13–01:31)

  • Initial studies found cognitive benefits of cocoa flavanols in rats, snails, and elderly humans.
  • Macelli’s research: He correlated average chocolate consumption with Nobel laureates across 22 countries.

• Statistical “Evidence” and Correlation (01:31–02:12)

  • Macelli describes the result: “When you correlate the two, there was an incredibly close relationship between the two... the chance this is random is less than 1 in 10,000.” — Franz Micelli (01:50)

• Anecdotes from Nobel Laureates (02:23–03:19)

  • Christopher Pissarides, Economics Nobel (2010): “Chocolate that makes you feel good might contribute a little bit. Of course, it’s not the main factor.”
  • Rolf Zinkernagel, Nobel laureate educated in Basel, Switzerland, confesses: “I am an outlier because I never have eaten more than maybe half a kilogram of chocolate per year.”

• The “Chocolate Controversy”: Satirical Reflections (03:19–04:07)

  • Eric Cornell, Physics Nobel (2001), jokingly: “I attribute essentially all my success to the very large amount of chocolate that I consume… milk chocolate makes you stupid. Dark chocolate is the way to go…”
  • Later, he issues a tongue-in-cheek ‘retraction’ for making such claims about chocolate types.

Statistical Insight

• Core Lesson: Correlation ≠ Causation (04:07–04:46)
  • Ruth Alexander emphasizes: “Just because you observe that the more chocolate a nation consumes, the more Nobel Prize winners it has does not mean that the one causes the other.”
  • Macelli admits there’s no clear explanation for the correlation, and invites listener hypotheses.

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2. The Dirty Truth About Toilet Seats — And Everything Else (04:46–08:53)

Summary

• Ruth Alexander transitions into exploring the idea of the toilet seat as a “benchmark” for germiness, prompted by listener skepticism over sensationalist hygiene claims.

Key Discussion Points

• Investigating the “Toilet Seat Standard” (05:40–06:23)

  • Expert: Dr. Chuck Gerba (Professor of Microbiology)
  • Gerba: “It’s one of the cleanest things you’ll run across in terms of microorganisms. It’s kind of our gold standard, too. There’s not many things cleaner than a toilet seat… because people… clean it all the time.”

• Surfaces That Are Far Worse Than the Toilet Seat (06:23–07:25)

  • Dr. Gerba notes: “There’s 200 times more fecal bacteria on the average cutting board than a toilet seat.”
  • On household items:
    • Sponges/cleaning cloths: “Maybe about 10 million or a million [bacteria] per square inch.”
    • Desktops: “About 400 times more bacteria than a toilet seat.”
    • Reusable grocery bags: “Some people have more fecal bacteria in their reusable grocery bag than their underwear.”

• International Hygiene—Which Countries Fare Best? (07:25–08:20)

  • Professor John Oxford (International Hygiene Council): “Countries like Australia and particularly Canada are kind of high up on the hygiene list… Countries near the bottom would be fairly routinely, unfortunately. India, for example, Malaysia.”

• Does All This Bacteria Matter? (08:20–08:53)

  • Oxford: “If you’re analyzing the water supply, you wouldn’t want to find one [E. coli]. . . Sometimes on the sponge, we’re finding 10 million. . . In a modern scientific society, what we want is people to recognize there is an issue here and take action.”

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Notable Quotes & Memorable Moments

• “Chocolate might make you smarter — but only if you’re a rat or a snail.” — Ruth Alexander (implicit summary, 01:31)
• “Correlation is not causation.” — Ruth Alexander (04:07)
• “There’s not many things cleaner than a toilet seat when it comes to germs.” — Chuck Gerba (06:07)
• “Some people have more fecal bacteria in their reusable grocery bag than their underwear.” — Chuck Gerba (07:11)
• “All these 18 [countries we’ve studied] rely on Lady Luck too much…or keeping their fingers crossed.” — John Oxford (08:47)

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Key Timestamps

• 00:13 — Episode introduction and setup for the chocolate segment
• 00:48 — Franz Micelli introduces the chocolate and cognition research
• 02:23 — Nobel laureates discuss their chocolate habits
• 03:19 — Satirical quote from Eric Cornell about chocolate and Nobel Prizes
• 04:07 — Core lesson: correlation is not causation
• 05:40 — Listener letter sets up the discussion of toilet seats as a bacteria standard
• 06:07 — Chuck Gerba debunks the myth of dirty toilet seats
• 07:25 — John Oxford discusses international hygiene standards
• 08:20 — Are household bacteria a real health risk?

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Conclusion

This episode deftly debunks the seductive simplicity of “statistical” stories in news and public health. From the myth that eating chocolate could bag you a Nobel Prize, to the misrepresentation of the toilet seat as humanity’s dirty baseline, More or Less showcases the importance of skepticism and statistical literacy — all served with a generous helping of wit.

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For more myth-busting statistical stories, or to submit your own questions, contact the show at [e-mail] or visit bbcworldservice.com/moreorless

Transcript

[BBC Announcer]

Thank you for downloading from the BBC. For details of our complete range of podcasts and our terms of use, go to bbcworldserveys.com podcasts

[Ruth Alexander]

hello, and welcome to More or Less on the BBC World Service, a little nugget of numerical nutrition. I'm Ruth Alexander and on the menu today. Does chocolate make you smarter? A study suggests it might Check. Chocolate produces brain power. Study links eating chocolate to winning Nobels. These headlines from around the world are reporting a paper published in the New England Journal of Medicine. The author of the study, a professor of medicine at Columbia University in the United States, Franz Micelle, says the starting point was some research which suggested that cocoa had health benefits.

[Franz Micelli]

There was a study published in the Journal of Hypertension looking at cognitive function in elderly subjects who did actually have mild impairment. And they put these patients on regular coca intake and they concluded that regular consumption of coca flavanols might be effective, improving cognitive function. There is data in the rats actually showing rats live longer and have better cognitive function when they eat chocolate. And even in snails, you can show that the snail memory is actually improved by chocolate as well.

[Ruth Alexander]

This got him thinking, could chocolate make you smarter? Short on any official measures, he took the number of Nobel Prize winners in a country as an indicator of general national intelligence and compared that with the level of chocolate consumption. He did this for 22 countries, and the results were striking.

[Franz Micelli]

When you correlate the two, there was an incredibly close relationship between the two. It had a P value of 0.0001, which means that this being to chance is less than 1 in 10,000. It gives you the probability whether this is a true finding or a chance finding.

[Ruth Alexander]

Following a sugar rush brought on by too many chocolate biscuits eaten with abandon, to try to bring you the best possible program, we conducted our own entirely unscientific survey of Nobel Prize winners.

[Christopher Pizaridis]

My name is Christopher Pizaridis and I won my Nobel Prize in Economics in 2010. And throughout my life, in fact, ever since I was a young boy, it's one of the things that I did to cheer me up. To win a Nobel Prize, you have to produce something that others hadn't thought about, you know, something different. And chocolate that makes you feel good might contribute a little bit. Of course, it's not the main factor.

[Rolf Zinkenotl]

Don't get me wrong, I'm Rolf Zinkenotl and I have been educated mostly in Basel and in Switzerland. Me personally, I am an outlier because I never have eaten more than maybe half a kilogram of chocolate per year.

[Ruth Alexander]

So mixed views there, but it's possible that not every Nobel laureate feels able to fully disclose their chocolate habit. More or less, it's discovered this subject is not without controversy. Here's what American physicist Eric Cornell, who won the Nobel Prize in 2001, told Reuters.

[BBC Announcer]

I attribute essentially all my success to the very large amount of chocolate that I consume. Personally, I feel that milk chocolate makes you stupid. Dark chocolate is the way to go. It's one thing if you want like a medicine or chemistry Nobel Prize, okay. But if you want a physics Nobel Prize, it pretty much has got to be dark chocolate.

[Ruth Alexander]

But when more or less contacted Eric Cornell for further comment, this was the response we received.

[BBC Announcer]

I deeply regret the rash remarks I made to the media with respect to the chocolate controversy. We scientists should strive to maintain objective neutrality and refrain from declaring our affiliation either with milk chocolate or with dark chocolate. Now, I ask that the media kindly respect my family's privacy in this difficult time.

[Ruth Alexander]

It might surprise you that somewhere in this program is a serious point. The chocolate study actually highlights a classic of statistics. Correlation is not causation. Just because you observe that the more chocolate a nation consumes, the more Nobel Prize winners it has does not mean that the one causes the other. There might be something else going on here.

[Franz Micelli]

We have a classic example where we cannot find a good reason why these two correlate so closely. Actually, you should ask your audience whether anybody has a good hypothesis on what is really going on here.

[Ruth Alexander]

Franz Micelli and if you have any ideas as to what could explain this correlation, do send us an email to more or lessbbc.co.uk now if the thought of rich dark chocolate has got you reaching for a snack, our next item might put you off. We've received this email from listener James

[Rolf Zinkenotl]

Dear More or less, I would like to propose that the toilet seat become the new international standard of measurement for numbers of bacteria. However, I was hoping you could first do some research into this liberally used microbial yardstick. After a recent news story on many UK hands being like dirty toilet seats, I wondered just what number is being referred to. I'm more than a little suspicious that behind this terrifying statement is a misused statistic and a twisted definition or two. Thanks, Loyalistener James Field James, just for

[Ruth Alexander]

you, we've been making friends with a man who's made a job out of swabbing toilet seats. Chuck Gerber, a professor of microbiology at the University of Arizona in the United States, spends his days measuring the amount of bacteria on all sorts of everyday surfaces in Particular, he's on the lookout for faecal bacterias like E. Coli and Staphylococcus aureus. So is it right that the toilet seat be considered the ultimate benchmark of dirtiness?

[Chuck Gerber]

Well, it's one of the cleanest things you'll run across in terms of microorganisms. It's kind of our gold standard, too. There's not many things that cleaner than a toilet seat when it comes to germs, I think because. Because people are so obsessed with the possibility of picking up germs, they clean it all the time.

[Ruth Alexander]

What are some of the dirtier objects then?

[Chuck Gerber]

Usually there's 200 times more fecal bacteria on the average cutting board than a toilet seat.

[Ruth Alexander]

Oh, that's awful. How does it get there?

[Chuck Gerber]

From raw meat products or some of the viscera from the inside of the animal? Because that's where a lot of the fecal bacteria originate.

[Ruth Alexander]

So the toilet seat is a surprisingly clean surface. How much bacteria is on the toilet seat, first of all?

[Chuck Gerber]

Well, you get about 50 bacteria per square inch. To compare that with a sponge or cleaning cloth, you usually have maybe about 10 million or a million per square inch of cloth or material. If you work in an office, many people don't realize they're talking dirty all the time because they never clean their phone. On an average desktop, where you're at right now, you have about 400 times more bacteria than a toilet seat to give you a rough idea, because at least you're cleaning the toilet seat. But most people never clean their desktop. Reusable grocery bags that you may use. Some people have more fecal bacteria in their reusable grocery bag than their underwear. They at least wash that.

[Ruth Alexander]

Oh, dear. It would seem the toilet seat gets an unfair press. We've also been speaking to the International Hygiene Council, which alarmed us by telling us that even when it looks clean, probably your kitchen sponge is the dirtiest thing in your home. The council's inspected homes in Australia, Canada, Germany, India, as well as Malaysia, Saudi Arabia, South Africa, the UK and the us so would Professor John Oxford, who chairs the Council, be drawn on which country is the germiest?

[John Oxford]

It's always a bit delicate, the countries which are the worst. We found that countries like Australia and particularly Canada are kind of high up on the hygiene list of people taking an interest and doing it. You know, there's two aspects here. Everyone's interested in it, but rather fewer people actually do something. Countries near the bottom would be fairly routinely, unfortunately. India, for example, Malaysia.

[Ruth Alexander]

But we all touch these startlingly dirty things every day, and yet most days we don't get ill. So do large numbers of bacteria really matter?

[John Oxford]

Well, these numbers of bacteria, particularly E. Coli, are huge. If you're analyzing the water supply, you wouldn't want to find one. You would not. So sometimes on the Sponge, we're finding 10 million, I think all of us, any country, all these 18 we've gone to, they're rely on Lady Luck too much or keeping their fingers crossed or sitting on their hands. In a modern scientific society, what we want is people to recognize as an issue here and take action.

[Ruth Alexander]

Which is why I'm thinking of going home to torch my kitchen sponge. If, like James, you have a question you'd like answering, please email us at more or lessbc.co.uk and you can visit our website for all our best stories in written form. Bbcworldservice.com More or less

[Franz Micelli]

there are dozens

[BBC Announcer]

of different podcasts now available from the BBC, including news, documentaries, science, business, arts and sports. The details of them all go to bbcworldservice.com podcasts.