More On The Egg Yolk Study

      36 Comments on More On The Egg Yolk Study

Last week I wrote about the latest Eggs Will Kill You! study conducted by Dr. David Spence, who seems to be making a career of anti-cholesterol and anti-egg hysteria.  (I’m sure the fact that he’s funded by statin-makers has nothing to do with that.)  When I wrote about the study, I only had access to the abstract and some media articles.  A reader in the research community later sent me a copy of the full study.  There are some interesting bits in there.  Let’s start with a paragraph from the introduction:

The underpinning of what used to be the step 2 diet and later became the diet recommended for CHD risk reduction by NCEP ATP III was a diet low in saturated fat (<7%) and dietary cholesterol (<200 mg). This diet if strictly applied tended to drive the consumer towards a more plant based diet with other potential advantages in terms of CHD risk reduction. In addition to saturated fat in meat (especially red meat) and full fat dairy products, eggs were also restricted due to their significant cholesterol content.

Right away we’ve got bias creeping into the text.  Notice how “tended to drive the consumer towards a more plant based diet” is simply assumed to be a potential advantage in terms of CHD risk reduction.

Currently, however, serious doubts have been expressed over the relevance of these dietary components to cardiovascular disease.

That’s because they’re not relevant.

In the case of cholesterol much of the debate has been focused on the lack of clear consensus on whether egg consumption consistently raises serum cholesterol or impacts negatively on postprandial events, including vascular reactivity. Most importantly the association of egg consumption with CHD events in cohort studies has been inconsistent.

Well, there’s a reason the association of egg consumption with CHD has been inconsistent:  eggs don’t cause heart disease.  If they did, the association would be consistent.  If the evidence supporting a hypothesis isn’t consistent, a good scientist assumes there’s something wrong with the hypothesis.

Here’s the description of how the data was collected:

In earlier years, data on smoking and egg consumption were recorded by patients into a lifestyle questionnaire at the time of referral. Since 2000, when our referrals were scheduled on an urgent basis soon after transient ischeamic attacks or strokes, a more limited set of lifestyle questions were asked at the time the history was obtained. These data were entered, along with the history, medications, physical examination and recommendations into fields in the database, from which clinic notes were generated.

Hmmm … so the study participants were people who’d been urgently referred to a clinic after suffering a heart attack or stroke.  Not exactly what I’d call a random sample of the population, or even a random sample of the elderly population.  And if egg yolks cause cardiovascular disease, why were the study participants who consumed less than one egg per week referred to a clinic for people who’ve had a heart attack or stroke?  Seems to me they should have been out playing golf and enjoying their plaque-free health, not seeking an urgent referral.

The responses for smoking and egg yolk consumption were used to compute pack-years of smoking (number of packs per day of cigarettes times the number of years of smoking) and egg-yolk years (number of egg yolks per week times number of years consumed). This was not done for alcohol consumption, licorice intake or exercise, because the textual responses were mainly not quantifiable (e.g. “quit drinking six years ago”, “plays golf twice a week”).

I guess I’ll have to ask my Canadian pals:  Why is licorice intake considered a potential confounding variable in Canada?  Do you eat enough of it to skew health outcomes? Granted, it’s been a long time since I did standup comedy tours in Canada, but I don’t remember noticing a lot of people up there chewing on licorice.  Nobody ever walked up to me after a set and said, “Great show, eh!  Can I buy you a licorice?”

As for not being able to figure alcohol intake or exercise into the data, I’d consider that a serious matter.  Later in the study, we also learn that waist circumference wasn’t included in the calculations.  In other words, we have no idea if we’re looking at more plaque in people who simply eat more eggs, or in fat people who never exercise and also eat more eggs – the folks Dr. Mike Eades calls non-adherers and I call people who don’t give a @#$%.

After a Results section describing the association between egg-yolks years and plaque I covered in the previous post, there’s a Discussion section calling for (surprise) a reassessment of the possible role of eggs yolks in heart disease.  Sure, the association is inconsistent, as we admitted earlier in the study, but since we managed to find one, it’s time to scare people away from eggs all over again.

My favorite paragraph in the study was this one:

The study weakness includes its observational nature, the lack of data on exercise, waist circumference and dietary intake of saturated fat and sources of cholesterol other than eggs, and the dependence on self-reporting of egg consumption and smoking history, common to many dietary studies.

Yes, those are weaknesses.  Big ones …  even bigger than not accounting for licorice intake.  But after noting in the full text that the observational nature of this study is a weakness, Dr. Spence ran out and told media reporters he’d demonstrated that egg yolks make plaque build up faster — cause and effect.

This wouldn’t be such a lousy study if the lousy scientist who conducted it didn’t jump to lousy conclusions and share them with media reporters who wrote lousy articles about it.


36 thoughts on “More On The Egg Yolk Study

  1. Beowulf

    I bet eating licorice causes narrowing of the arteries since it is a narrow-shaped tube. Despite evidence proving this connection, I shall abstain from placing licorice directly into my arteries. After all, I’m already consuming 18 egg-yolks per week on average, so it pays to be careful.

  2. Lori

    “Since 2000, when our referrals were scheduled on an urgent basis soon after transient ischeamic attacks or strokes, a more limited set of lifestyle questions were asked at the time the history was obtained.”

    I’m sure patients’ recollections of their diet were crystal clear right after having a heart attack or stroke. Even on my best day, I couldn’t tell you how many eggs I eat in a week, even though I do all the shopping and cooking at my house. Someone who never goes near a stove or a grocery store and just beat the Reaper is going to be making wild guesses about their egg eating. Why do people even bother with this kind of data.

    They bother because it keeps the funding coming in.

  3. nonegiven
    Most cases of hypertension from liquorice were caused by eating too much concentrated liquorice candy.[33] Doses as low as 50 grams (2 oz) of liquorice daily for two weeks can cause a significant rise in blood pressure.[34]

    Yeah, but who’s eating all this stuff? I haven’t even heard anyone mention eating licorice in years.

  4. Andy

    This stuff cracks me up. I just did a short research paper for a freshman level anatomy and physiology class on LDL particle size, its effects on CAD, and how diet affects it. It took all of 10 minutes to pull studies from pubmed that showed larger LDL consistently and independently determined lower heart disease risk, and that less carbs/more fat consistently resulted in larger LDL particles than vice versa. Yes, an undergrad and heavy metal drummer by profession just debunked the USDA, AHA, egg yolk study, etc.

    Drummers and standup comics are known for their study debunking.

  5. Marilyn

    What is this with licorice??? I just got a call today that my order for xylitol licorice chewing gum has been canceled because the FDA has blocked the sale of it. If licorice were that scary, I’d have been dead before I got to high school.

    Xylitol licorice chewing gum? That product exists?

  6. Phyllis Mueller

    Another possibility in this group of people is egg allergy. A good many people are allergic to eggs, either more drastically (ingestion causes breathing problems) or less so (ingestion may trigger a milder reaction that may not seem connected, like eczema or joint pain). In allergic people, eating eggs could/would cause inflammation, which could, eventually, cause vascular problems. That’s probably something else that wasn’t tested for (or reported).

    Good point.

  7. Erik

    Very perceptive and amusing analysis, as often is the case when you look at bad science.

    I’m very intrigued about what will come out of NuSI when Gary Taubes and Peter Attia launch it in September with regards of bringing more rigor to nutrition science.

    I wish them well.

  8. Firebird

    In the end, they will be left with egg on their faces…and proceed to sop it off with a slice of white bread.

  9. Matt

    Did you notice the difference between of age at first visit between the egg yolk years groups? Almost 70 for the highest and around 55 for the lowest. Same trend for eggs/week. Shouldn’t it have been the frequent egg eaters being urgently referred to the clinic in their 50s?

    BTW, saw this in the comments at Don Matesz’s blog by “Jack LeBear” – just wanted to give proper credit.

    Excellent point.

  10. Marilyn

    “Xylitol licorice chewing gum? That product exists?”

    Well, it did — has for years. I bought it from one company online and they stopped carrying it, and so I turned to another company and bought from them for some time. Sure wish I’d known. I’d have stocked up! I just got some xylitol cinnamon gum from the same company today, and it’s ghastly!

    Thanks, Nonegiven. The only thing I could find is that 2 oz per day for two weeks might cause heart arrhythmia. But good grief! If licorice is being taken off the market because a few people might eat a lot of it and might have a problem, what’s next? Peanut butter removed from the market because a few people could have a fatal allergic reaction to it? Shrimp removed from the market because some people are deathly allergic to it?

    Helene, maybe a trip to Holland would be in order. (I’d probably get picked up for smuggling a dangerous substance, however.) When I was in Rome, I bought some licorice mint gum, that I really enjoyed. 🙂

  11. JK

    Hey, licorice is WONDERFUL! As a Dutchman I have been raised on the stuff! It helps with colds, sore throats and stomach upsets. It helps me to concentrate when really necessary and it simply tastes divine.
    But since it contains salt it has been fingered as the cause of high blood pressure… yet this has never been proven. Not even with post normal science. So bugger off, all those who don’t like the stuff. I love it and will keep eating it.

    I’ve apparently been unaware of a large licorice subculture out there.

  12. Marilyn

    JK, not only does it help with colds, sore throats and stomach upsets, it’s said to be good for dental health. Coupled with xylitol, which is also good for dental health, xylitol/licorice gum is a win-win combination. But the most important consideration is, yes! it simply tastes divine.

  13. JK

    Ah, you didn’t know about that subculture that doesn’t eat licorice? Probably because they are such a small group, wouldn’t it? Or because the name “drop”, as we Dutchies call it, confuses those who only think it is called licorice? And the high blood pressure thing was based on the fact that the kidneys can only excrete an X amount of salt per hour, so any more salt in the diet must stay in the body, according to the researchers. That we excrete even more via sweating did not occur to them and the medical world has used this against us ever since.

  14. Linda

    Decided to follow Rosie O’Donnell on Twitter for awhile but it got too depressing. The medical staff has totally brainwashed her, total vegan diet now.

    She posted a pic of today’s breakfast, all veggies, not a drop of fat! Of course there are lots of other vegans cheering her on. I tweeted, along with others, pleading with her to look into Dr. Eades, Gary Taubes, Dr. William Davis, etc.

    Oh well, “you can lead a horse to water…………………………..”

    I asked her where was the bacon and eggs?

    Sorry to hear she’s going that route.

  15. Firebird

    I prefer Spry gum made with xylitol, peppermint or spearmint. If I want licorice (which I don’t), I’ll put a drop of stevia on my tongue. 🙂

  16. Marilyn

    Yes, Firebird. There are some things that have a “kind of” licorice flavor — anise and fennel to name a couple — but, alas, they aren’t quite as tasty. 🙂

  17. Janelle

    “…fat people who never exercise and also eat more eggs – the folks Dr. Mike Eades calls non-adherers and I call people who don’t give a @#$%.”

    I think a lot of fat people who never exercise (and eat eggs) do give a @#$%, but exercising when you’re truly fat can be problematic, if not nearly impossible.

    That’s true, and of course the definition of “non-adherers” is more involved than that. They’re people who don’t really give a hoot about much of anything and tend to be irresponsible, whether we’re talking about health, education, finances, relationships, etc. Dr. Mike Eades pointed out awhile back that in clinical drug trials, non-adherers are the ones who don’t take their pills on schedule. In both the intervention and placebo groups, the non-adherers end up with worse health outcomes on average, which can lead people only looking at the intervention group’s data to assume the drug is effective. After all, the people who didn’t take the drug regularly had worse results. But that doesn’t explain why people who faithfully take their placebos also have better outcomes than people who don’t.

    The reason, Dr. Eades pointed out, is that adherers and non-adherers are different in many ways, including their attitude about life in general. If you believe a positive attitude helps keep you healthy (I certainly do), it’s no surprise that non-adherers have worse health outcomes, even if we can’t trace those results to a specific variable in a study.

  18. Kay

    Curse you Fat-Head! Everytime I read your post, I always end up reading something else, like Dr Eades adherence post….which was very interesting.

    But I have to be a pain-in-the-you-know-what about your comment “If you believe a positive attitude helps keep you healthy (I certainly do), it’s no surprise that non-adherers have worse health outcomes,…” Well, I’m sorry but I know a couple adherers who have a consistent lifestyle and they are healthy, but I would never ever call them positive, if anything they are more curmudgeonly. So please, don’t tell us that we “have to think positive” mantra to be healthy. If your a curmudgeon or laugh all day long, I think learning (from people like you) and living a healthy lifestyle on a consistent basis, you’ll be healthy….and maybe seem more positive.

    Now that I think of it, maybe those healthy adhering curmudgeons are taking statins and that’s why they’re curmudgeons! 🙂

    I don’t believe a positive attitude is required to be healthy — my grandmother lived to age 95 and was a hypochondriac and chronic complainer — but I think it helps.

  19. Underground

    “So bugger off, all those who don’t like the stuff. I love it and will keep eating it.”

    Yeah, you can have my share.

    Ugh, I never could see how anyone could enjoy eating that stuff. I got some as a child and I thought they were trying to punish me.

  20. Paul

    Hi Tom,

    I wondered whether you have heard about Lord Strathcona I found the reference to it in Barry Groves’s articles :- Lord Strathcona

    In his autobiography, Discovery, Vilhjalmur Stefansson gives a detailed account of Lord Strathcona’s dietary habits which illustrate well how a restricted diet can be eminently healthy.

    After Stefansson had told Lord Strathcona what he had learned from the Eskimos, His Lordship told Stefansson that years ago in Canada he had begun a regimen all his own. He told how he had begun to wonder why, since he liked some things better than others, he should bother to eat something different on one day when he had liked what he had eaten the previous day better. ‘This led’, recounts Stefansson, ‘to his questioning what he really did like and, when he got the answer, eating nothing else — eggs, milk, and butter.’

    Stefansson was frequently a guest at Lord Strathcona’s home in Grosvenor Square, and so had plenty of opportunity to observe him. He wrote: ‘Strathcona, a broad shouldered man taller than six feet, would be seated at one end of the long table, Lady Strathcona at the other. As course after course was served to the rest of us, he would converse, drinking a sip or two of each wine as it was poured. Sometime during the middle of the dinner, his tray was brought: several medium soft boiled eggs broken into a large bowl, with plenty of butter and with extra butter in a side dish, and, I believe, a quart of whole milk, or perhaps half and half.’

    Lord Strathcona must have been doing something right because lived entirely healthily to the ripe old age of 93.

    So if you feel like eating eggs for breakfast every day, these stories illustrate that there is not really much reason why you shouldn’t.

    Incidentally, I get through a couple of dozen extra-large eggs a week — and have been doing so for over half a century. And I am still here! Mind you, I am only in my late 70s (although that is longer than either my father or his father lived). I strongly believe that eggs, which contain all the materials needed to build a complete animal, are probably the best food it is possible to get.

    In the book “Kabluna,” a writer who lived with the Inuits in the 1930s recalls meeting a priest who had eaten nothing but fish, caribou and seal for several years. He was fit as a fiddle.

  21. Dan

    In my experience, serum cholesterol is inversely proportional to egg consumption. When first going on low carb, I increased egg consumption and decreased grain consumption and my serum cholesterol decreased. I’ve had other similar ups & downs in the last few years. This whole egg-cholesterol business is nonsense.

  22. Janelle

    I’m a big supporter of placebo–it’s the ultimate “do no harm” treatment. In the end, it’s your body that does the work anyway, so the fewer confounding factors (surgery, drugs) the better, IMO.

  23. gollum

    Well, he is saying the short-term effect of eggs on endothelium has been measured directly and it is not so good. Said to be preventable by antioxidant preloading (like, 1 g of vitamin C). I am not sure I buy it – remember that brilliant age/cumulative eggs thing – but it is not prima facie absurd; compare with carbs, eating too much carbs does not raise fasting BG in healthy subjects – in the short term – still it is not a good idea. (The effect may still be physiological, and the antioxidants masking a natural response, or they may have shot their foot – I mean, study, because they were desperately trying to find what they expected, I don’t know. I keep hearing of almost-centenarians in good health and their egg-and-bacon-breakfasts.)

    Liquorice is a good example for how not all risks are equal in the eyes of Big Nanny Sister (fluoride, LD50, supermarket would be another one). I do not hate liquorice, I do dig it, love the taste, and not all its effects are negative; but the fact remains that it does have quite some pharmalogical effects, some of which are definitely able to work against you. What does Big Sister do about it? The bags must have “Liquorice for adults, not for kids” printed on them. No one actually cares. No age check, no Coalition against Liquorice abuse (“more oranges” maybe?), no black-bordered scare box “Liquorice may make you tensed about your increasing hypertension” or such.

    This must be something Americans just don’t hear much about. You can travel all over the country and not hear anyone talking about licorice.

  24. LCNana

    Hi Tom. We should differentiate between liquorice, and liquorice “candy.” Pure liquorice is quite different and hence can cause some health problems if eaten in any quantity. Some of the stuff is simply liquorice flavoured candy and would be harmless – other than the crap in it….

    Shows what I know about licorice. I’m still mystified as to why this is considered a confounding variable in Canada.

  25. Ailu

    OMG! I’ve eaten an average of 14-16 eggs a week for the last 4 years (uh, and we won’t talk about the shameless addiction to bacon) and I just got my blood test results back – my Chol/HDL Ratio is 1.1 and my triglycerides are at 30! Yikes! Someone dial 911 before I keel over!

    Honestly, I feel so persecuted. LOL

    Dr. Spence is now claiming that eggs give you heart disease without raising your cholesterol. He’ll still be claiming that as he passes from this world and we egg-eaters are still alive and kicking.

  26. George Henderson

    Paul, I loved the Strathcoma story and looked for more details; turns out his bio says that oats were also part of his limited diet. Either Steffanson had a selective memory or Strathcoma had just gone gluten-free when Steff saw him.

    Tom, great of you to dig up the liquorice angle which other commentators missed. Spence should do a paper that just focusses on liquirice and heart disease and leave the frickin’ eggs alone.
    I love how he magically seperated eggs into pure yolk. What a prankster.

  27. Ailu

    Janelle says:
    August 27, 2012 at 11:32 am
    I’m a big supporter of placebo–it’s the ultimate “do no harm” treatment. In the end, it’s your body that does the work anyway, so the fewer confounding factors (surgery, drugs) the better, IMO.

    @Janelle: Loved this! Ah and sooo true!

  28. Lee

    I like your stuff, don’t get me wrong. But after reading your rant about movie pirates obtaining your film illegally, I’m curious about the copyright on this study and the process whereby you obtained a copy of it from a reader in research.

    The reader receives research papers as part of his job and sent me a copy. Excerpting from a study (or book, or film, etc.) for the purposes of commentary and analysis has long been considered fair use. If I made the entire study available for free downloads online, that would be a different matter.

    If people want to include clips of Fat Head in a commentary or review, that’s fine with me.

  29. Lee

    Understood that the reader is entitled to have the research paper for his/her research, presumably because the researcher has paid for it or is otherwise entitled to a copy as a member of an organization. And if he/she cites it, agreed it is fair use. I do not understand how it is legal for the researcher to transfer a copy to you unless you have properly paid for it. That was what piqued my curiosity. Did you pay for your copy of the article? And if so, whom did you pay? The publisher? The author? The researcher? Or is your copy pirated?

    I’m not an expert on all the aspects of copyright law, but I believe making a copy for reference material is considered fair use. If not, thousands of journalists, students and librarians are guilty of copyright infringement. When I working at a magazine (pre-internet days), we routinely visited research libraries, took academic journals or other periodicals off the shelves, and made copies of articles for research. If the article we wanted was on microfiche, a helpful librarian would even find it and make copies for us. The librarian never told us that only the library, as the original purchaser of the journal article, could cite it.

    If we’d re-published the entire article that would of course be a different matter. But no one, including the magazine’s attorneys, ever suggested that making a copy and then using that copy strictly as a reference for background or excerpts in our own publication was a form of copyright infringement. Determination of “fair use” use is based on:

    1. the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
    2. the nature of the copyrighted work;
    3. the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
    4. the effect of the use upon the potential market for or value of the copyrighted work.

    If I email a university librarian and ask for a copy of an academic journal article to use as reference material for my blog and he or she emails me an electronic version, is it copyright infringement? I don’t know for sure, but I would suspect it isn’t. The copying is for purposes of education or commentary, we’re not re-publishing the work substantially or in its entirety, and we’re not affecting the journal’s ability to exploit its own property. By the same token, if a journalist who wanted to review Fat Head made a copy of the DVD his brother bought to take home and refer to while writing the review, I wouldn’t consider it copyright infringement. I’d consider it fair use.

    By contrast, people who upload Fat Head to YouTube or torrent sites are re-distributing the whole film and they are definitely diminishing the market value of the work.

    There was an interesting case we covered in a media law class I took in college: a Hollywood studio sued a TV station for copyright infringement because the station’s movie reviewer copied clips of a film into his pre-recorded review. The studio claimed the movie review was entertainment and they hadn’t granted permission for the clips to be copied and aired. (I take it they didn’t like the review.) The court dismissed the case, saying that a review is commentary, even if the audience finds the commentary entertaining.

    In a similar vein, I paid a license fee for most of the news footage in Fat Head, but one news network (I don’t recall which) refused to grant permission. (I already had a copy of the footage that I’d ordered from a media research library.) I consulted an attorney, who wrote a letter saying that the footage was being used to educate my audience, it was a small clip from a newscast, and that using it would in no way affect the market value of the network’s newscasts, so we were using under the Fair Use clause. The reply from the network was basically, “Uh … okay. You win.”

  30. Lee

    Okay. Well, I believe you are ill informed about what constitutes fair use. Given that the Atherosclerosis website states “Full-text articles are available from 1961 to the present. Access to full-text articles is limited to members of EAS, IAS, SAIP and other subscribers,” you may want to do a little more research on copyright law or consult your lawyer.

    That could be, but again, if it’s available in libraries, access is not actually limited to the groups they named. It’s available to anyone with a library card. Copyright notices never list the exceptions for fair use, at least not that I’ve ever seen.

  31. Tom Blakeslee

    Notice at end of the egg article:
    CONFLICT OF INTEREST: None of the authors receives funding from purveyors of margarine or eggs. Dr Spence and Dr Davignon have received honoraria and speaker’s fees from several pharmaceutical companies manufacturing lipid-lowering drugs, and Dr Davignon has received support from Pfizer Canada for an annual atherosclerosis symposium; his research has been funded in part by Pfizer Canada, AstraZeneca Canada Inc and Merck Frosst Canada Ltd.


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