Category Archives: Eggs and Heart Disease

Is It Time To Stop Eating Deadly Eggs Or Time To Stop Putting Nutritional Epidemiology In The Headlines?

After carefully ingesting the new JAMA egg study that has gotten the media and many patients in a tizzy I consumed a three egg (of course with yolk) omelette.

I am happy to report that I survived the incident and am not concerned at all that my longevity has been compromised.

My 2013 summary of eggs, dietary cholesterol and heart disease (see here) is still valid and I highly recommend patients and readers read that post plus my updates on eggs with newer data (see here and here) rather than information related to the new egg study.

Although CNN and other news outlets lead with an inflammatory headline suggesting that eating those 3 eggs increased my risk of heart disease the new egg study could not possibly prove causation because it was an observational study.

Nutritional epidemiology has come under considerable criticism in the last few years for churning out these weak observational studies .John Ionaddis has been particularly vocal about these limitations, writing:

A large majority of human nutrition research uses nonrandomized observational designs, but this has led to little reliable progress. This is mostly due to many epistemologic problems, the most important of which are as follows: difficulty detecting small (or even tiny) effect sizes reliably for nutritional risk factors and nutrition-related interventions; difficulty properly accounting for massive confounding among many nutrients, clinical outcomes, and other variables; difficulty measuring diet accurately; and suboptimal research reporting. Tiny effect sizes and massive confounding are largely unfixable problems that narrowly confine the scenarios in which nonrandomized observational research is useful

This egg study contains the usual flaws that render it inconclusive:

First, the study relies on data collected from a food frequency questionnaire. Have you ever sat down and tried to recall exactly what you ate in the previous week? How accurate do you think your estimate of specific food items would be?

Ed Archer has written about the inaccuracy of the food frequency questionairres extensively. Here’s a sample from one of his devastating critiques;

In lieu of measuring actual dietary intake, epidemiologists collected millions of unverified verbal and textual reports of memories of perceptions of dietary intake. Given that actual dietary intake and reported memories of perceptions of intake are not in the same ontological category, epidemiologists committed the logical fallacy of “Misplaced Concreteness.” This error was exacerbated when the anecdotal (self-reported) data were impermissibly transformed (i.e., pseudo-quantified) into proxy-estimates of nutrient and caloric consumption via the assignment of “reference” values from databases of questionable validity and comprehensiveness. These errors were further compounded when statistical analyses of diet-disease relations were performed using the pseudo-quantified anecdotal data. These fatal measurement, analytic, and inferential flaws were obscured when epidemiologists failed to cite decades of research demonstrating that the proxy-estimates they created were often physiologically implausible (i.e., meaningless) and had no verifiable quantitative relation to the actual nutrient or caloric consumption of participants.

In addition to unreliable initial data the subjects were followed up to 30 years without any update on their food consumption. Has your food consumption remained constant over the last 30 years? Mine hasn’t. I went from avoiding eggs to eating them ad lib and without concern for my cardiovascular health about 5 years ago after looking at the science related to dietary cholesterol.

It’s Hard To Get Around Confounding Variables

Observational studies like this one try to take into account as many factors as they can which might influence outcomes. Invariably, however, there are factors which are unaccounted for, indeed unknowable, which could be influencing the results.

Individuals who were avidly trying to follow a healthy lifestyle in 1985 likely had drummed into their heads the message when these questionnaires were filled out that they needed to limit egg consumption. These individuals were also likely following other healthy habits, including exercising more, smoking less, and eating more fruits and vegetables and less junk food.

Observational studies cannot account for all these confounding variables.

At science-media centre.org they do a fantastic job of having independent experts in the field present their evaluation of scientific studies which have been popularized in the media. For the JAMA egg study their analyses can be found here.

Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University emphasized the problem with residual confounding :

That’s because, for instance, there will be many other differences between people that eat many eggs and people that eat few other than their egg consumption.  These other differences might be what’s causing higher death rates in people who eat a lot of eggs, rather than anything to do with the eggs themselves.  The researchers point out that this has been a particular problem in some previous studies, and that this may have been a reason for inconsistency in the results of those studies.  They have made considerable efforts to allow statistically for other differences in the new study.  But they, correctly, point out that their own study is still not immune from this problem (known as residual confounding), and that therefore it’s impossible to conclude from this new study that eating eggs, or consuming more cholesterol in the diet, is the cause of the differences in cardiovascular disease rates and overall death rates that they observed.

For observational epidemiological studies like this egg study which show increased risks that are only “modest” it is highly likely that the next such study will find something different.

Eggs Are Not Eaten In Isolation

Finally, It’s important to remember that eggs, like most foods, are rarely consumed without accompanying food. This accompaniment is often bacon in the US. Eggs are often cooked in oil or butter and unless you cook them yourself you are unlikely to know the nature of the oil.

Eggs are frequently components of recipes.

We have no idea how these factors play into the results of the egg study.

So, rather than drastically cutting egg consumption I propose that there be a drastic cut in the production of weak observational nutrition studies and a moratorium on inflammatory media coverage of meaningless nutritional studies.

Eggsponentially Yours,

-ACP

N.B. For a good article on this topic read Julia Volluz of Vox on why nutritional science is so messy

A Heart Healthy Egg Nog Holiday Toast From Dr. and Mrs. Skeptical Cardiologist!

The skeptical cardiologist wrote a post extolling the virtues of egg nog back in 2013.

Today I’m reposting it and wishing all my readers and patients a great Christmas and a fantastic 2019.

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It’s Christmas Eve and you are starting to make merry. Time to break out the egg nog? Or should you eschew this fascinating combination of eggs, dairy and (often) alcohol due to concerns about heart disease?

egg

    • Cardiac deaths

increase in frequency

    • in the days around Christmas.

Could this be related to excessive consumption of egg nog?

Egg nog is composed of eggs, cream, milk and booze. All of these ingredients have become associated with increased risk of heart disease in the mind of the public.
Nutritional guidelines advise us to limit egg consumption, especially the yolk, and use low-fat dairy to reduce our risk of heart disease

A close look at the science, however, suggests that egg nog may actually lower your risk of heart disease.

Eggs are high in cholesterol but as I’ve discussed in a previous post, cholesterol in the diet is not a major determinant of cholesterol in the blood and eggs have not been shown to increase heart disease risk.

Full fat dairy contains saturated fat, the fat that nutritional guidelines tell us increases bad cholesterol in the blood and increases risk of heart attacks. But some saturated fats improve your cholesterol profile and organic (grass-fed, see my previous post) milk contains significant amounts of omega-3 fatty acids which are felt to be protective from heart disease.
Milk and dairy products are associated with a lower risk of vascular disease!

Whether you mix rum, brandy, or whisky into your egg nog or you drink a glass of wine on the side you are probably lowering your chances of a heart attack compared to your abstemious relatives. Moderate alcohol consumption of any kind is associated with a lower risk of dying from cardiovascular disease compared to no alcohol consumption.

So, drink your egg nog without guilt this Holiday Season!
You’re actually engaging in heart healthy behavior.

Eggnoggingly Yours,

-ACP

The Eggsoneration Continues: Why Does Anyone Eat Egg Whites?

The skeptical cardiologist pointed out in 2013 that there was no good evidence supporting limiting dietary cholesterol to 300 mg per day.  I exulted, therefore, in 2016 , when this long-standing dietary recommendation came out of the US dietary guidelines.

Recognizing that dietary cholesterol doesn’t need to be limited means that eggs and egg yolks are fine.

Egg Whites: A Product of Nutritional Misinformation?

Why, then do egg whites continue to be created and consumed?

On a regular basis, patients tell me that they are eating egg white omelettes because they believe egg yolks are not heart healthy.

Old bad nutritional dogma takes a long time to reverse apparently. To this day, for example, the National Lipid Association still recommends limiting daily cholesterol consumption to <200 mg/ day

Therefore I find it necessary to highlight additional new studies that further eggsonerate eggs.

To wit, I shall briefly discuss two articles that were published earlier this month and brought to my attention by friends and readers who are aware of my rabid support for the egg.

Article One: The Wonderfully Acronymed DIABEGG Study

Entitled  “Effect of a high-egg diet on cardiometabolic risk factors in people with type 2 diabetes: the Diabetes and Egg (DIABEGG) Study—randomized weight-loss and follow-up phase” our fist study was performed in Australia at the Sydney Medical School,

Investigators randomized 128 patients with prediabetes or type 2 diabetes (T2D) to a high egg or a low egg diet.

Throughout all study phases, including the 3-mo weight-loss phase, participants consuming the high-egg diet were instructed to eat 2 eggs/d at breakfast for 6 d/wk (12 eggs/wk). Those in the low-egg group were directed to consume <2 eggs/wk, and to match the protein intake that the high-egg group had consumed at breakfast with 10 g lean animal protein (meat, chicken, or sh) or other protein-rich alternatives, such as legumes and reduced-fat dairy products (also consumed at breakfast). Recommended egg-cooking methods were boiled or poached, but they could also be fried if a polyunsaturated cooking oil, such as olive oil, was used. The prescribed diets were energy and macronutrient matched, as reported previously

At the end of 12 months both groups had lost about 3 kg in weight.
The investigators measured everything they could to look at diabetic and cardiometabolic biomarkers which might suggest adverse effects of egg eating on the cardiovascular system but they could find no difference between the egg eaters and the non egg eaters.
High egg consumption had no adverse effects on the following factors that are felt to be important in the development of atherosclerosis:

-measures of systemic and vascular inflammation [high sensitivity C-reactive protein (hs-CRP), IL-6, soluble E-selectin (sE-selectin)],

-oxidative stress (F2-isoprostanes), the adipokine adiponectin (which also modulates insulin resistance), and

-glycemia [fasting plasma glucose, glycated hemoglobin (HbA1c), and a medium-term measure of glycemia, 1,5-anhydroglucitol (1,5AG)].

The authors suggested that nutritional guidelines stop worrying about limiting eggs.

Article Two: Half A Million Chinese Can’t Be Wrong

This observational study published in Heart found that egg consumption in a huge Chinese population was associated with less stroke, and major cardiac events (MCE):

Compared with non-consumers, daily egg consumption was associated with lower risk of CVD (HR 0.89, 95% CI 0.87 to 0.92). Corresponding multivariate-adjusted HRs (95% CI) for IHD, MCE, haemorrhagic stroke and ischaemic stroke were 0.88 (0.84 to 0.93), 0.86 (0.76 to 0.97), 0.74 (0.67 to 0.82) and 0.90 (0.85 to 0.95), respectively. There were significant dose-response relationships of egg consumption with morbidity of all CVD endpoints (P for linear trend <0.05). Daily consumers also had an 18% lower risk of CVD death and a 28% lower risk of haemorrhagic stroke death compared to non-consumers.

The lower risk for stroke and cardiovascular death in egg eaters persisted after accounting for known CVD risk factors.

(And yes, I agree this is an observational study which we should take with huge grains of salt and pepper).

Are EGG Whites The Skim Milk Scam of The Egg Industry?

I’ve written about the scam that is skim milk but it occurs to me that egg white consumption is equally nonsensical.

What happens to the wonderfully nutritious yolk of the egg when it is brutally separated from its white? It is put in a container and sold as  liquid egg yolk. Makers of mayonnaise are big consumers of liquid egg yolk.

Thus, like dairy farmers who double their sales by selling skim milk and its dairy fat separately, egg producers are probably delighted that Americans are consuming egg whites , allowing them to get two products from a single egg.

As I wrote previously: not everyone is an egg lover and I’m fine with that. There is no evidence that you have to eat them. You could feel towards them as did Alfred Hitchcock :

“I’m frightened of eggs, worse than frightened, they revolt me. That white round thing without any holes … have you ever seen anything more revolting than an egg yolk breaking and spilling its yellow liquid? Blood is jolly, red. But egg yolk is yellow, revolting. I’ve never tasted it.”

For those that don’t find yellow revolting, however, avoiding egg yolk makes no nutritional sense.

Eggsplicatively Yours,

-ACP