Behind the Headlines goes deeper than “eating egg yolks as bad as smoking”

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I was out of the office, so the UK site Behind the Headlines beat me to the punch in analyzing this study and discussing some of the news coverage about it.  Some news eggs-cerpts:

  • CBS News asked, “Should a carton of eggs contain health warnings like a carton of cigarettes?” And their headline was: “Eating egg yolks leads to two-thirds of the plaque buildup you’d see in a smoker’s arteries, study shows.”  Did the study show that?
  • A New Jersey site asked, then answered – “Are Egg Yolks Unhealthy as Cigarettes? New Study Has an Answer.” The problem is that the study didn’t answer that, and the story’s last sentence made it clear that the study didn’t answer that.

I could go on because Google produces more than 150 news story returns on the topic, but you’d be better off reading the Behind the Headlines conclusion:

This study found that egg yolk consumption was associated with increased fatty build-up in the arteries of the neck, though this was small when compared to the build-up expected with age. This study has important limitations which mean that it cannot be concluded that egg yolks are as bad for you as smoking:

  • Average egg yolk consumption per week and duration was evaluated through a questionnaire response. These are only estimates and may include a considerable degree of inaccuracy. Consumption may vary over time. We also don’t know how these eggs were prepared (boiled, fried in oil, scrambled in butter, etc).
  • This wasn’t a trial, and so people are choosing the number of egg yolks they eat. People who ate more egg yolks may differ in other health and lifestyle factors from people who ate less, and this may account for their different artery build-up. For example, as the researchers rightly acknowledge, they did not thoroughly assess other dietary factors, exercise or waist circumference. It is possible that higher egg yolk consumption could be associated with less exercise and higher overall saturated fat intake – both well known risk factors for heart disease. The small changes in fatty build-up in the arteries seen with higher egg yolk consumption could have been accounted for by these other factors.
  • None of the participants in this study were reported to be suffering from heart disease and the heart arteries were not examined.
  • We do not know how or whether the extent of fatty build-up in the neck arteries was associated with build-up in the heart arteries.
  • This is a relatively small, select sample of people attending a vascular clinic in Canada, and further quality studies would be needed to better assess the question.

Addendum 30 minutes after original post: posted, “Egg Study Not All It’s Cracked Up To Be.

Another addendum 90 minutes after original post:  One journalist has just pointed out to me that university news releases often add to the hype.  That journalist sent me the news release from The University of Western Ontario, headlined, “Research finds egg yolks almost as bad as smoking.”  If I could find additional funding to staff such an effort, I’d launch a News Release Review project in a heart beat.

Another addendum 8 days later:  Cassandra Willyard posted her own coverage of the coverage  – called “Egg-ceptionally Bad” on “The Last Word on Nothing.”


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Susan Fitzgerald

August 17, 2012 at 3:23 pm

Whew, thanks for clearing that one up. I was worried! Soon as I saw that headline, I immediately clicked over to your blog to get the real scoop. thanks!

Robert James

August 19, 2012 at 3:08 am

There are studies, and there are studies. I read the articles on the recent developments concerning egg consumption and your comments with great interest.

First, studies like this recent one are, collectively, valuable since they provide a starting point for debate and analysis. Normally, unless there is some glaring error or missing factors, an observational study can have definite value so I did take the results of this study seriously. The objections you raise are certainly valid, but still, assuming some sort of random distribution of confounding factors, those confounding factors would have to be very strong to completely dismiss the statistical validity of the study.

I did begin thinking about the problem of what weight to place on the study and realized there is one overlooked factor that could have a large impact on the results. For a good number of years I avoided eggs because the “rap”on eggs was highly negative. It’s only been over the last year or so that I change my opinion, again based on “studies”. So I was thinking that at least a decent portion of the persons surveyed reacted as I did over a long period of time, that is, avoided eggs out of concern for personal health. So it may well be likely that the persons with the lowest egg consumption were those most concerned about their health and who may have followed other “healthy” practices in larger numbers than those who ignored the warnings on eggs over the years who, presumably, were less concerned about person health. That effect could very likely account for the differences. Persons more concerned about their health and who likely acted accordingly by consuming less eggs when publicity was “bad” for eggs, would likely be the healthiest because they proactively acted on their concerns in other ways, such as keeping their weight down and eating a healthier diet, more than the higher egg consumers. This could easily explain the discrepancy.


August 20, 2012 at 6:32 am

What worries me about these publications is that it makes us numb on healthinfo. More and more I hear peolple say: “Youn can’t do anything that isn’t bad for your health nowadays.” I seriously worry that it discourages healthy behaviour. Because it is true. There is website on anything stating it to be bad for you. Epidemiology should not disencourage us, but help us. It is plain simple (KISS), don’t smoke, eat reasonable, move reasonable, drink moderately and use your common sense.
A headline like “eating egg yolks as bad as smoking” supports tobacco-industry … It is not just the statistics, it is also the semantics…..