Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
15 Aug

Are Eggs Really as Bad for Your Arteries as Cigarettes?

This past weekend, amidst all the Ancestral Health Symposium madness, I caught the headline while flicking through my phone for a few brief seconds. Didn’t open it up, though. Just cruised on past. I’d hoped to just forget about it, to ignore it, to banish it to the back of my mind where half truths and junk studies go to die. And truth be told, I pretty much had forgotten about it until I checked my email to find a ton of frantic emails from readers wondering if their beloved and dependable egg yolk breakfasts were killing them faster than the cigarettes they don’t smoke. What? You didn’t hear?


Followed by (with less hysterical capitalization) “May increase carotid plaque build-up.”

So what are we looking at here?

We’re looking at a study in which a trio of researchers (two of whom with extensive ties to the statin industry) quizzed a group of middle-aged and elderly stroke patients about their lifelong egg intake and smoking history, making sure to stress the importance of accuracy and honesty in their answers. Yes, you heard me right: they expected people to remember every last egg they ever ate. Still, everyone in the study was assumed to have supernatural memory, so I guess it evens out.

Those who ate the most eggs were the oldest – almost 70 years old on average, compared to the relatively sprightly 55 year-old egg avoiders. It’s pretty well accepted that with age comes the progression of atherosclerosis, a process that takes, well, time to occur. Plaque doesn’t just snap into existence; it develops. All else being equal, the older you get, the more plaque you’ll have.

Those who ate the most eggs also smoked the most and were the most diabetic. To their credit, the authors tried to control for those factors, plus several others. Although they tried to control for sex, blood lipids, blood pressure, smoking, body weight index, and presence of diabetes, the study’s authors didn’t – couldn’t – account for all potentially confounding variables. In their own words, “more research should be done to take in possible confounders such as exercise and waist circumference.” Hmm. “Possible” confounders, eh?

Exercise reduces inflammatory markers of atherosclerosis.

Exercise even reduces markers of atherosclerosis in pre-pubertal obese children!

Exercise reduces thickness of the carotid arterial wall. It doesn’t get much clearer than that. Exercise is a massively confounding variable that the authors failed to take into account.

What about waist circumference?

A high waist circumference predicts atherosclerosis of the carotid artery.

Or how about stress, which also wasn’t considered?

Perceived daily psychological demands – the amount of crap you perceive to be heaped on your plate – are associated with progression of carotid arterial plaque.

Yeah, it’s not like the size of a person’s waist, whether or not they move of their own volition or sit in an easy chair all day, and how much stress they endure have any impact on their risk of developing atherosclerosis. Those things may be linked, and I’m sure the authors would have loved to include them in their analysis, but there just wasn’t enough space on the questionnaire. Besides, it’s not like a little physical activity and mediation could even undo the damage wrought by 4.68 sinful egg yolks per week. Why, that’s nearly a half dozen!

Seriously, though, the subjects were all stroke patients who’d lived to tell the tale. They’d been in contact with the medical community (you generally don’t just shake off a stroke without medical attention), who no doubt gave them the standard required advice to prevent another event, which includes “a reduction in saturated fat and cholesterol intake…and a boost in physical activity.” Since the egg-eaters obviously didn’t listen to their doctors’ recommendations to cut back on cholesterol intake, I’d wager they treated the exercise recommendations with similar levels of disdain. What do you think?

Here’s what I think: this is an observational study whose already limited worth depends entirely on the memory of an inherently fallible creature being infallible. As such, it cannot assign causality, contrary to what the media (“Egg Yolks Can Quicken Hardening of the Arteries“) and authors (“It has been known for a long time that a high cholesterol intake increases the risk of cardiovascular events”) say. Furthermore, why single out egg yolks? I mean, I get it – the authors sort of have a vendetta against eggs – but what about other foods? Were those even analyzed or asked about? What about the stuff that people generally eat with eggs, like pancakes and vegetable oils, or the foods that contain egg yolks, like baked goods and mayonnaise? For all we know, egg yolk intake could have been a marker for eating garbage; most people aren’t tossing raw yolks into post-workout shakes, gently poaching eggs with coconut vinegar, or horrifying co-workers with a bag full of hard-boiled eggs like we Primals are wont to do. They’re getting Grand Slams at Denny’s, eating bologna sandwiches with mayo on white bread, and overcooking scrambled eggs in canola oil until they’re rubber.

For fun, though, let’s look at what some other studies have found with regards to the artery-clogging capabilities of whole eggs:

Egg consumption and endothelial function: a randomized controlled crossover trial. Two eggs daily did not impair endothelial function (the flow of blood through the arteries), nor did it increase total or LDL cholesterol. Overall, eating two eggs a day elicited no change in cardiovascular health when compared to eating oatmeal (a cardiologist’s pride and joy).

Daily egg consumption in hyperlipidemic adults – effects on endothelial function and cardiovascular risk. In patients with high cholesterol, eating several hard-boiled eggs a day had no effect on endothelial function.

Effect of a high-saturated fat and no-starch diet on serum lipid subfractions in patients with documented atherosclerotic cardiovascular disease. Obese patients with heart disease ate lots of saturated fat, zero starch (including zero grains – sound familiar?), and tons of vegetables, and saw massive weight loss without any negative effects on their blood lipids. Once upon a time, I had access to the full study (it was freely available at the website for the Mayo Clinic, who’s since taken it down…wonder why), and I remember seeing that they ate three or four eggs a day. If egg yolks were bad for all heart disease patients, these guys would have felt the effects.

Okay, despite all those confounders and other egg studies that support yolks as harmless and the fact that this was merely an observational study without the power to assign causation and whose authors failed to even propose a potential mechanism of action, let’s entertain the notion that something was going on with this population of egg eaters. What if the egg yolks did have something to do with the atherosclerosis?

In a previous post on “Human Interference Factor,” I highlighted a study showing hens given an unnatural industry-standard diet high in omega-6 containing grains (soy and corn) produce less healthful eggs than hens on a more natural diet of grains lower in omega-6 with supplementary antioxidants. When subjects ate two of the soy/corn-fed eggs a day, which were high in omega-6 fats, their oxidized LDL levels were increased by 40%. Subjects who ate two of the other eggs each day, which were low in omega-6 fats, had normal levels of oxidized LDL (comparable to subjects in the control group, who consumed between two and four eggs a week). Since the oxidation of LDL particles is strongly hypothesized to be a crucial causative factor in atherosclerosis, it’s conceivable that eating normal, industrial eggs could have a negative effect on carotid plaque.

Anyway, what are the takeaways here?

Exercise, practice stress reduction, and get your waist circumference checked.

Don’t smoke.

Don’t age.

Don’t pay too much attention to ridiculous observational studies (this is part of stress reduction).

Oh, yeah – eat egg yolks, and lots of them. Doubly so if you’re low-carb (remember the starch/grain-free high-egg diet referenced above). Make ’em pastured, if possible, or at least from hens that ate something besides soy and corn. They’re more nutritious and probably “safer” than industrial eggs.

(In retrospect, that mention of the authors’ ties to the pharmaceutical industry was a low blow. After all, I myself am a direct benefactor of my local pastured egg industry; they pay me in delicious golden yolks.)

I hope you found this post helpful. Have at it in the comments.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. It amazes me the way that people respond to information like this. It is the same reason that cigarette smoking killed so many people in the years priors to the late 1960’s.

    Smoking, like food habits are hard to change. I guess that people’s will will have to be broken down by disease and / or deaths in one’s family.

    Bill Morten wrote on August 18th, 2012
  2. Thanks, Mark, for changing your mind and tackling this egg yolk panic inducing media blurb.

    I looked up some sources and foun an enormous list of international names with no background data attached. I know Europeans don’t use the MD after their names, but I am wondering if this was a list of miscellaneous people, all with a vested interest in pharmaceutical companies.

    All I did about it was to comment: “check out Paleo/Primal scientists’ findigs.”

    Hope they did. Hope they checked out YOURAS!

    Susan Holland wrote on August 18th, 2012
  3. I actually just did an interview with Tom Naughton of Fathead fame for my blog and near the end he brought up this very point. “Don’t pay attention to the sensational headlines because they’re based on bad science.” I’m paraphrasing.

    But he’s right. These “scientists” do a very limited observational study and consider it gold.

    JB Primal wrote on August 18th, 2012
  4. Today was my last day at work before I head to college. One of my customers asked me what I was majoring in, and so I told her, Dietetics and Exercise Science. Upon hearing that I was interested in nutrition her eyes popped out of her head and she said “Did you hear that egg yolks are as bad for you as cigarrettes?!” I simply rolled my eyes and said, “Yes, that’s a bunch of bull. I’m still eating eggs.” :) On top of that, a few months back, my dad was diagnosed with high blood pressure. the doctors wanted to put him on high blood pressure medicine but he refused. After that doctors appointment, I introduced him to low carb primal eating and helped him with an exercise plan and he lost about 30 pounds. That being said, he eats eggs and bacon every morning for breakfast. Today was a follow up appointment to see if his blood pressure got better. Needless to say it did. Guess cigs aren’t that bad for us after all? lolol. CW makes me so mad.

    Sarah wrote on August 18th, 2012
  5. Here on Bainbridge Island, WA, I pay $6.00 a dozen for fresh, local eggs in glorious colors! But, to me .50 an egg is a cheap meal. I eat one a day, poached on a large wad of steamed spinach, red pepper and onion for breakfast. Tried the 30-day vegan challenge to address cholesterol and my triglycerides went way up! Now will try a 6 week carb sensitivity program because I believe my side of the family is highly carb sensitive with insulin resistance. I am also wheat-free after reading Wheat Belly.

    Maggielynne wrote on August 23rd, 2012
  6. in case anyone wants to see the good doc Spence respond

    comments section

    Mark wrote on August 23rd, 2012
  7. My partner will be presenting this study to his research group this week as an example of “how not to over-interpret the ‘results’ of a poorly designed study”. He’s a physicist working on imaging (MRI) coronary arteries, with particular emphasis on atherosclerosis. Thank you for writing this post, which I referred him to as soon as I realised he’d found the journal article and planned to speak about it (I also referred him here: I’m sure it will be instrumental in providing him with talking points – as I said, he’s a physicist, so having better medical references to hand will help when the MDs in his group start arguing about saturated fats and cholesterol.

    We’ve both been primal devotees for about two years, and eat easily over a dozen (pastured and beautifully orange-yolked) eggs a week apiece. I was livid when I read the study in question, and am glad that it’s garnered such attention, to be honest – if only as a vehicle for us to explain why observational studies are useless in saying that “X/Y/Z is bad for you”. Correlation is NOT causality, particularly where confounding factors are involved. Now, if only I could make my students understand that concept…

    Thespianpythia wrote on August 27th, 2012
  8. There is no such thing as “Critical Thinking.” It’s just thinking, some with more detail and some with less.

    There’s no need to bring humanist dogma into a discussion about eggs.

    Indigo wrote on August 28th, 2012
  9. Without digging deeper; I would have been misled by such a study. I would have thought that a serious doctor did a serious study; in a serious medical journal. To see the bad science; lack of follow up on confounding factors; and financial ties to mega drug companies; (drug pushers) is just beyond the pale. Financial ties to statin makers and they even let this drek get published?

    zebonaut wrote on February 3rd, 2013
  10. I’ve been wondering how many eggs is to many. I’ve gone a week before eating 4 eggs every day and would gladly eat more but i’m worried that it’s to much. any thoughts on how much is to much?

    Jason wrote on March 4th, 2013
  11. Growing up I never gave much thought into questioning the experts. I mean they went through a lot of schooling to get labeled an expert so why should I question them then as I grew wiser with age I started to think about who funded the project, who is conducting the project (are there conflicts of interests) and their past studies in this or other fields. Once the thinking came I realized that the “experts” are mere mortals trying to make a living and pay their bills. I do my own research now and only look at studies after I do a little research on the who, what, when and whys.

    Matt wrote on May 28th, 2013
  12. Also… amount you eat is a confounder. If you generally eat more than most people, you probably have higher cholesterol AND you probably eat more eggs.

    Christine O. wrote on August 4th, 2013
  13. Hubby is diggin that I am primal. Enjoying his bacon and eggs again without the critical eye. Here in AZ we have a great little garden that sells fresh eggs as fresh as today for $5 doz. Awesome part, you can see how these chickens and Turkeys live. No doubt these the best eggs I have ever eaten!

    liz wrote on August 11th, 2013
  14. Even though it’s an older post, this is a great example of common fitness misconceptions today. Great article and I’m glad I gave it a read. I love eggs so to hear the contrary statement from popular belief is awesome. Now if I could only convince my wife….. :)

    Jason wrote on October 8th, 2013
  15. I love eggs. Always have. And when I retire I will live where I can keep my own chickens and I will eat eggs until the day I die, God willing and the creek don’t rise!

    DJ wrote on January 11th, 2014
  16. This is the perfect site for everyone who wants to understand
    this topic. You realize so much its almost hard to argue with you (not that I personally would want to…HaHa).
    You certainly put a brand new spin on a subject that has been discussed for years.
    Wonderful stuff, just wonderful!

    privacy tool wrote on May 27th, 2015
  17. I saw this in an email I received and I was shocked and angry. So I paste this sentence into Google search and came up with 730,000 articles containing this \phrase. “Consuming the amount of cholesterol found in just a single egg-a-day appears to cut a woman’s life short as much as smoking , 5 cigarettes a day, for 15 years”
    This is appalling to make statements like this and the uneducated public believes it.
    So glad I found this rebuttal, thank you for posting the article. Some truth exists.

    Leslie Carmody wrote on August 6th, 2015
  18. Wow. How and why you brought politics into this debate is beyond me. Name-calling is unnecessary. BTW, will you be “eating them up verbally” with gems like “a much more safer egg”? And when did they start capitalizing the word farmer?

    Trav wrote on August 16th, 2012
  19. What the heck is this about and what is it in response to? One thing that I like most about this blog is the lack of politics. Please lets not bring that tripe here.

    Agi wrote on August 16th, 2012
  20. Hmmm.. I clicked “reply” to respond to a guy who was very rude to someone who wasn’t sure what to think about the blog post, but I guess something went wrong.

    Trav wrote on August 18th, 2012
  21. Maybe his post was deleted as abusive? Anyway, I don’t see it anymore. Sorry for the confusion.

    Trav wrote on August 18th, 2012

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