Friday, August 31, 2012

Are Eggs Really as Bad as Cigarettes for Our Health?


The short answer is NO. The question stems from an August 14th article in The Atlantic, Study: Eggs Are Nearly as Bad for Your Arteries as Cigarettes. It wasn't until the 2nd sentence in the article that the author went off the rails with the claim: "Because egg yolks are high in cholesterol, eating whole eggs increases cholesterol, a known risk factor for coronary artery disease (CAD) and heart attacks."

Wow, I thought that nonsense had been dispelled years ago, but seems we need to do it again - dietary cholesterol has a very minimal correlation with blood concentrations of cholesterol. Saturated fat in the diet is correlated with blood cholesterol levels. This brief summary of the issue is from Discovery Health:
About 85 percent of your blood cholesterol level is endogenous, which means it is produced by your body. The other 15 percent or so comes from an external source -- your diet. Your dietary cholesterol originates from meat, poultry, fish, seafood and dairy products. It's possible for some people to eat foods high in cholesterol and still have low blood cholesterol levels. Likewise, it's possible to eat foods low in cholesterol and have a high blood cholesterol level.  
At this point, the whole study has been discredited, since all of their conclusions follow from the false premise.

As discussed by Cassandra Willyard at The Last Word on Nothing, the majority of the media did not even bother to check facts or speak with experts about the study. The one exception is Sydney Lupkin at ABC News who, you known, spoke to other doctors and researchers and revealed how deeply flawed the study is, beyond it's flawed premise.
“This is very poor quality research that should not influence patient’s dietary choices,” said Dr. Steven Nissen, who chairs the department of Cardiovascular Medicine at the Cleveland Clinic Foundation, in an email. “It is extremely important to understand the differences between ‘association’ and ‘causation’.”

Nissen said the researchers relied on patients to recall how many eggs they consumed, but asked them once and assumed it remained constant, which isn’t reliable. He said the way researchers measured patients’ plaque has come under “considerable criticism,” and that researchers failed to adjust for other dietary factors.

Dr. David Frid, a cardiologist at the Cleveland Clinic, told ABCNews.com he doesn’t think smoking should be equated with eating eggs because eggs have an indirect rather than direct impact on heart disease. The eggs have to first increase cholesterol to create plaque build-up. The impact of smoking on heart disease is direct because smoking causes arteries to become inflamed, which prompts the body to respond with plaque.

He said the study fails to take exercise or other dietary habits into account. Study participants could have consumed more salt, or they could have been on cholesterol-reducing drugs, too.

“It may be that people who consume a lot of eggs also consume a lot of other fatty foods,” Frid said, adding that how the egg is prepared should also be taken into account.
Beyond the failed study itself, the media handled this so badly that it becomes a perfect case example of how poorly the media handles science.

[T]he good headline potential was too tempting for several media outlets to ignore and the story ran widely, and in some cases without any comment from outside experts

Dr. Tom Linden, a medical journalism professor at the University of North Carolina,said journalists should exercise caution when writing about studies like this. He said they should put the studies into context by explaining the caveats and consulting experts.

“The danger here is headline writers who aren’t necessarily science writers may go way overboard in headlining the story,” Linden said.

Linden said his bottom line is that journalists and readers should be cautious when they interpret study results. Studies need to be put in context beyond the snappy headline or lead.
We need more writers like Lupkin, authors who do research and talk to other experts.
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