“Egg yolks almost as dangerous as smoking!“ We can see it now – legal age limits for eating eggs, children being grounded for dipping their toast soldiers in their friends’ egg yolks behind the shed in the back lane, restaurants with a ban on omelettes!
The internet was ablaze with headlines likening eggs to tobacco, but most failed to mention serious flaws with the media reports *and* the original research paper. Once again, correlation does not equal causation…
Let’s start with our concerns with the CBC article. We understand that the media plays in important role in disseminating research findings, and while great information is always valuable (honestly we are not being facetious here), linking eggs to heart disease is not a novel idea; we’re not sure what the huge hype is about. In fact, we are willing to bet that if this research hadn’t been phrased in terms of smoking risk and suggested Canadians were being deceived by the egg industry it would have received absolutely no media attention! The short post by the CBC catches readers with a fear-mongering, sensationalized title and then proceeds to leave out all of the details of the study it doesn’t even reference!
There are so many factors that affect one’s cholesterol levels and the formation of arterial plaques, none of which are mentioned in this news article. Were the participants young, old, at risk for CVD, hypercholesterolemic, overweight, physically active, etc? What other dietary factors were involved? How many eggs were these participants eating per week? The CBC report simply implies that eggs are harmful for everyone, full stop!
Now on to the original research from Spence, Jenkins and Davignon (1), who have published in this area before. If you actually read the research article, it answers several questions the CBC article did not:
- The study participants were attending a vascular prevention clinic, often after transischemic attack (TIA) or stroke (though this is not explicit in the methodology). Obviously, participants had some concerns regarding risk or personal history of vascular disease at baseline.
- At baseline, participant were older (mean age was 62 years old), overweight (mean BMI = 27), smokers (median 5 smoking pack-years) with comorbidities and cholesterol issues (13% with diabetes, mean high triglycerides, etc.). Again, this is a high risk population.
- Diet and lifestyle outcomes were limited to smoking and weekly egg intake via a “lifestyle questionnaire”, of which no details are provided. No information was collected on intake of alcohol, red meat, saturated fat, sodium, fish, fibre, etc. or level physical activity. As such, other important dietary or lifestyle factors were not captured nor controlled for in the analysis.
The study results suggest that eating three or more eggs per week is associated with greater arterial plaque formation. Their conclusions were as such:
“Our findings suggest that regular consumption of egg yolk should be avoided by persons at risk of cardiovascular disease (emphasis ours). This hypothesis should be tested in a prospective study with more detailed information about diet, and other possible confounders such as exercise and waist circumference.” (1)
While this conclusion is much more moderate than what was blasted in the media, we think the term “avoid” is far too strong given the complete lack of controlling for confounding dietary and lifestyle variables.
What if you had 6 slices of bacon with your three eggs every Sunday morning? Any impact the bacon had on your arterial plaque formation would be lost in this data set and falsely attributed solely to egg yolks! What if those with high intakes of eggs are also sedentary? Likewise, this study would never distinguish a difference. Pretty poor methodology, we think!
Now let’s get to some of the grandiose statements made by the study authors. The comparison to the Monster Burger is ignorant and inappropriate. Comparing two foods on a single nutrient is foolish. I’d take the egg with less than 100 calories and only 5 g of fat over the Hardee’s Monster Thick Burger that weighs in at 1,420 calories and 107 g of fat any day.
No Baloney’s advice. We would like to point out that although two extra large eggs exceed the recommended daily cholesterol limit (between 200 and 300 mg/d), it is important to keep overall nutrition in mind and note that Canada’s Food Guide (flawed though it may be) does not suggest you eat two eggs every day! Furthermore, there is no rule that says you have to eat two. Perfectly fine to have half a serving from the Meat and Alternatives food group from an egg and the other half from peanut butter (zero cholesterol). Variety and moderation are the cornerstones of a healthy diet!
As for CBC (insert finger wagging here), if you are going to promote highly inflammatory comments such as these, at least do your readers the courtesy of providing the link/reference to the peer-reviewed manuscript with details of the study design. Let them evaluate the quality of the research and make an informed decision about their nutrition! To show you how it’s done here is the link to the abstract in PubMed (unfortunately the full article is not open access, so you will have to pay to read it).
We’re sticking to our original take on eggs and egg yolks, thank your very much! (see our previous post, The Yolk – A Burden or Blessing?)
1. Spence JD, Jenkins DJ, Davignon J. Egg yolk consumption and carotid plaque. Atherosclerosis 2012; Epub ahead of print.