Written By Tom Nikkola - Director of Nutrition and Weight Management
If you haven’t heard the latest news about nutrition, rumor has it that eating an egg yolk is as bad a smoking a cigarette. At least that’s what the news headlines have been telling people. This is an example of the constant challenge we face in trying to deliver accurate information to people about their health and nutrition habits. In the span of a day or two, the media can create mass confusion about something as nutrient-rich and healthy as a simple egg. The headlines help get traffic to the various websites, but for the unfortunate readers, most of these media sources do little to nothing when it comes to investigating the actual study. They look for the opportunity to pounce on another saturated fat or cholesterol story, and in the pursuit of article readership, they skip over a key component to good journalism — doing research before publishing a story.
I’m also fascinated by the way the media grabs hold of stories such as these, which have the possibility of confusing people and making their nutrition habits worse. But they won’t focus on other stories, such as the latest “real” research study that showed drinking orange juice is bad for your heart health and ability to manage weight. At any rate, before you toss your carton of eggs, you should know a little more about the “study” people have been talking about. You can find the abstract here, or pay for the access to the full article, which we did. I’d rather invest the money in something else, but to provide an accurate article it was important to review the paper in full.
Egg Yolks and Plaque Formation
You’ve probably heard the story many times. It usually goes something like this: Fat and cholesterol from food easily pass from your digestive system into your bloodstream where they stick to the walls of your arteries and causes plaque buildup. This story has been told so many times, people think it’s the truth in how arteries get clogged. The truth is, the process is far more complicated than that. If you’d like to spend some time learning more about this topic, my friend Peter Attia did an excellent series on cholesterol called The Straight Dope on Cholesterol. I highly recommend reading it.
Based on the fact that the “study” was titled “Egg yolk consumption and carotid plaque,” you may think the “study” showed eating eggs led to plaque formation. This “study” showed no such thing, nor could it the way the “study” was designed. By the way, I keep putting study in quotation marks because when most people read the word, they think of at least a couple of groups being put on specific diets or accurately measuring smoking habits in a population of people. This wasn’t that type of process. Instead, it was the result of patterns seen by asking patients some questions.
The authors of the journal article reviewed answers to a small questionnaire that was answered by patients attending a hospital program specializing in vascular health. As patients would come in, they were asked a small list of questions, which included how many eggs they ate each week and how many packs of cigarettes they smoked each day. Even with access to the full journal article, the questionnaire and all the data included from it, was not made available. From the disclosed answers, the article authors created their own metrics called “Egg years” and “Pack years.”
Egg years were calculated as the number of eggs patients ate, times the number of years they ate them. Think about that for a moment. If I were to ask you how many eggs you eat every week and for how many years you’ve done so, how certain would you be in the answer? Unless you’ve never eaten eggs, you’d likely have a hard time knowing the right answer. Nevertheless, this is the measurement these researchers used. They did the same with cigarettes, by asking how many packs a day the patients smoked and for how many years they’d been doing that.
In essence, the questionnaire was designed to look for just a few behaviors related to health and to identify common patterns. What the study cannot do in any way is show that any behavior causes a health outcome (like plaque formation). It would be like asking a bunch of executives across a variety of companies what cars they drove. If Mercedes was the most common car among the group interviewed, there would be an associationbetween the cars selected and the positions these individuals held. Of course, no one would suggest the car choice caused these individuals to be promoted into their positions. It’s just an association.
What we have with this study, similar to what we see with eating meat, is an association. Those in this study group who ate the most eggs also tended to be most overweight and also tended to smoke more. The study authors tried to control for other variables, but their questionnaire was quite limited. Since we don’t know what other questions were asked, we don’t know if other patterns evolved. In all likelihood, had the right questions been asked, there would have been other patterns related to plaque formation such as alcohol, refined carbohydrates or sugar, stress, sleep, vitamin and mineral intake, etc. In all likelihood, those who ate eggs more often also made lifestyle choices that led to plaque formation. It’s not likely that nature-made, nutrient-rich egg yolks are to blame.
To further add to the issues with the study, the group was divided up into fifths. Each fifth of the group had a progressive increase in plaque development. I created a table below to explain.
As you can see, age looks to be the most serious risk for the development of heart disease, which is already well known. There’s nothing newsworthy about that finding. However, one thing that is glazed over is cholesterol. The study authors have tried to build a case against dietary cholesterol — especially in eggs, — before. You may remember the news headlines from two years ago declaring a single egg was worse than a Hardees Monster Thick Burger and other fast food meals. The authors of this “study” were the same ones behind the “study” in 2010 that created a media ruckus about fast food meals being better than eggs. Tom Naughton wrote an extensive review on that study here.
The foundation of the authors’ argument against eggs is their cholesterol content. The authors say “meals high in cholesterol should not be consumed regularly by those at risk for cardiovascular diseases, as dietary cholesterol itself is harmful, and potentiates the effect of saturated fats.” Yet, if you look in their own study data above, those who consume the most eggs have the lowest cholesterol. This should not be a surprise as dietary cholesterol has been shown to have a minimal effect on blood cholesterol levels. Even though the authors continue to point fingers at dietary cholesterol, their own data suggests it’s not the issue. Though it was not noted in the current study’s paper, their 2010 paper Dietary cholesterol and egg yolks: Not for patients at risk of vascular disease does point out the conflict of interest for two of the authors, who have spoken for and received payment from “several pharmaceutical companies manufacturing lipid-lowering drugs.” The continued finger pointing at dietary cholesterol as a major cause of heart disease appears to be unwarranted based on available, controlled diet research. It’s observational studies like these that keep the theme alive and help the media spread unjustified concern about nature-made foods like eggs.
If you’re thinking, “Maybe I should just toss the yolk and eat the white,” look at what you’d be missing out on. The yolk is where almost all of the nutrients are found. According to the USDA Database, an egg yolk contains:
Summary
It’s unfortunate that most media channels don’t do a little homework before spreading stories like the idea that eating an egg yolk and smoking a cigarette are the same thing. If you attempt to understand what a good diet entails by reading media headlines, you’ll easily become confused. Smoking cigarettes has been shown tocontribute to the development of heart disease. Eating egg yolks has not. While we don’t fall back on a single “diet” to make our nutritional recommendations at Life Time, there’s a lot that could be learned from the Paleo diet movement. The biggest thing is that the most nutritious foods are those we eat with the smallest amount of modification or processing. An egg is about as close to natural as you can get. Based on the nutrient value of eggs, I’ll keep eating mine. In fact, I was eating some as I was working on this article.
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This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.
