Introduction 

Eggs and Our Health is intended for an audience of health professionals as well as for the general public. We understand that the diversity of our audience means that some people who are reading this may not be familiar with the scientific terminology, acronyms and symbols used so we have provided a glossary for terms that we feel may require an explanation. These terms will be indicated by active links that will redirect you to our glossary. Note: Some links may redirect to an outside source.

Our goal here is to provide you with the most accurate, independent information as it relates to egg consumption and human health. To ensure accuracy in our content, we have been advised by a number of individuals to whom we are genuinely grateful. We hope you find “Eggs and Our Health” informative.

The Confusion Around Cholesterol

What is cholesterol? Cholesterol is a fat-like substance that circulates in the blood and is found in virtually all the cells in your body. It is essential to maintaining good health. In fact, your body requires cholesterol to help build cells. Fortunately, our bodies are capable of producing all that we need from our liver. All non-essential cholesterol is acquired through eating animal-based foods like eggs. This is often referred to as “dietary cholesterol”.

LDL Cholesterol vs. HDL Cholesterol

It is very likely you have also heard of “good” and “bad” cholesterol. These refer to LDL (low-density lipoproteins, the “bad” cholesterol), and HDL (high-density lipoproteins, the “good” cholesterol).

What's Bad About LDL Cholesterol?

LDL cholesterol can join with other fats and cling to the inner-walls of your arteries. Over time, this can lead to plaque build-up, narrowing of your arteries and reduced blood flow. This in turn can lead to atherosclerosis, heart attack or stroke. 

What's Good About HDL Cholesterol?

HDL cholesterol can help protect you from the effects of LDL cholesterol by carrying away some of the fat from your arteries and protecting against disease. 

Medical illustrations courtesy of: The American Heart Association

Cholesterol and Risk

For almost five decades it has been conventional wisdom that dietary cholesterol should be limited. For the average person, this means consuming less than 300 mgs per day, and less than 200mg per day for hyper-responders, those with type 2 diabetes or pre-diabetes and those who are at risk of cardiovascular disease - which is most people who “expect to live past middle age”.[1] For the record, one average sized egg contains approximately 215 mgs of dietary cholesterol.

Despite these long-standing restrictions, a flurry of media reports recently have cited studies now claiming that dietary cholesterol does not actually increase overall cholesterol levels in the blood. These studies claim we no longer have to be concerned about these previous restrictions. In other words, feel free to eat as many eggs as you want! And, shockingly, some studies are even suggesting that eating eggs can actually reduce the risk of heart disease.

Even the United States Office of Disease Prevention and Health Promotion as far back as 2015 were advised by a panel to drop any recommendations that limit cholesterol intake. It is of particular interest to note that Dr. J. David Spence, professor of pharmacology and clinical neurology at the Robarts Research Institute, Western University in London, Ontario, Canada, who has written extensively that this recommendation, has been “heavily influenced by propaganda from the egg industry”.[2]

Dr. Michael Greger, M.D. FACLM, reveals in the following video how the egg industry has spent hundreds of millions of dollars on propaganda despite having been convicted of false advertising – a case they lost on appeal to the U.S. Supreme Court:

Propaganda is described on Wikipedia as, “a form of communication that is aimed towards influencing the attitude of a community toward some cause or position by presenting only one side of an argument. Propaganda is usually repeated and dispersed over a wide variety of media in order to create the chosen result in audience attitudes . . . . and to further a political, religious, or commercial agenda.”

So, what propaganda does the egg industry rely on to promote their commercial interests? Dr. Spence has written, “. . . the red herring is a misplaced focus on elevated fasting levels of LDL cholesterol as the main or only harmful effect of dietary cholesterol”.[3] The real concern is how, and when, blood cholesterol levels are measured as an indicator of health concerns.

Blood Cholesterol Levels: Post-prandial vs. Fasting Cholesterol

For much of our lives we exist in a post-prandial (or post-meal) state. It is in this state that our cholesterol levels are highest which, in turn, contributes to endothelial dysfunction over time. This state exists from the time we eat breakfast, through lunch, dinner and all the snacking we do in between. A fasting state is the opposite of a post-prandial state and it primarily covers the period of time from mid-evening, or several hours after we've consumed our last meal of the day, through our sleep and until we wake in the morning.

Dr. Naomi D.L. Fisher, Associate Professor, Harvard Medical School, has highlighted the importance of post-prandial cholesterol as the preferred state for measurement and has stated, “Perhaps more important, large-scale analyses have shown that non-fasting lipids don’t weaken the connection between cholesterol levels and harmful events like heart attack and stroke. In fact, post-meal measures are thought to strengthen the ability of lipid levels to predict cardiovascular risk. This observation may stem from the fact that most people eat several meals plus snacks during the day. That means we spend most of our time in a “fed” state, not a fasting state. So lipid levels after eating may best reflect our normal physiology.” In other words, measuring cholesterol levels of subjects in a post-prandial state are not only more relevant, but more accurate of predicting cardiovascular risk.

The following video further explains post-prandial measurement vs. fasting cholesterol measurement as it relates to cardio-vascular risk and how the Egg Nutrition Center (an arm of the marketing entity the American Egg Board) design misleading studies.

Conversely, the levels of fasting cholesterol, “are determined mainly by heredity, insulin resistance, obesity, and factors other than what was consumed the previous day”.[4] Thus, “much more important than the effects on fasting lipids are the post-prandial effects."[5] “Dietary cholesterol above 140mg in a single meal markedly potentiates post-prandial lipemia”.[6] And independent of other dietary factors, two studies reveal that egg consumption increased the risk of new-onset diabetes.[7][8]

Other Harms of Dietary Cholesterol

There are other ways in which dietary cholesterol can have a significant impact on health and bodily function. “Dietary cholesterol worsens macrophage accumulation in adipose tissue”.[9] Adipose tissue is essentially fatty or loose, connective tissue that stores energy. Adipose tissue is also an endochrine organ and produces hormones. Macrophages are a type of white blood cell of the immune system. Macrophage accumulation can disrupt metabolic and endochrine function and lead to complications normally associated with obesity.

“Dietary cholesterol also induces monocyte chemoattractant protein-1, contributing to hepatic steatosis”.[10] Symptoms of hepatic steatosis, (or fatty liver) is pain usually under the rib cage, abdominal swelling, jaundice and fever.

Most of these same studies that falsely declare dietary cholesterol doesn’t increase overall cholesterol in the blood, have sought to redirect focus and lay all the blame at the feet of saturated fat.

What Are Saturated Fats?

Fat consists of two molecules: fatty acids and glycerol. Saturated fat is where the fatty acid chains are single bonds. Those with double bonds are unsaturated fats (1 double bond = monounsaturated, and >1 double bond = polyunsaturated). To put it as simply as possible: Saturated fats have a solid consistency at room temperature, while unsaturated fats are typically a liquid at room temperature.

Saturated fats are usually associated with animal products such as meat, dairy, eggs, processed meats and pre-packaged snack foods. Unsaturated fats are usually associated with more plant-based foods like nuts, plant oils like canola and vegetable, olives and avocados.

The conventional wisdom is that saturated fat is less desirable in your diet than unsaturated fat. It is recommended that saturated fat intake should be limited to around 5-6% of your total daily caloric intake. It is important to note again at this stage, one egg contains enough cholesterol and saturated fat that can exceed your recommended daily intake or "RDI" (see again figure 1).

Saturated Fats and LDL Cholesterol

“The widespread emphasis on saturated fat as the main determinant of fasting levels of LDL is also misplaced: Dietary cholesterol is permissive of the effects of saturated fat on fasting lipid levels. Saturated fat has a much greater effect on fasting LDL when it is consumed with cholesterol.”[11] However, the “effects of saturated fat must be considered in relation to cholesterol intake.” Cholesterol is still the primary concern and dietary cholesterol can exacerbate the effects of saturated fat and not necessarily the other way around. This has often been called the “bacon and egg effect”.[12] The egg industry has misappropriated this information in an effort to promote the falsehood that dietary cholesterol is benign.

Determining the Risk Factor of Dietary Cholesterol

The western diet of affluence (one heavy in meat, dairy and eggs) is generally not a good diet. Because eggs are not the only source of dietary cholesterol, it is often difficult to contrast those who already consume dietary cholesterol via meat and dairy with those who consume eggs in addition to those foods. In other words, it’s like showing the difference that smoking 1-½ packs of cigarettes a day is relative to smoking 1 pack of cigarettes a day.

However, take a culture with a relatively healthy diet and then add eggs into controlled trials and the harm can be seen. “A study by Trichopoulou et al. in Greek diabetics showed that an egg a day increased coronary risk 5-fold, and each 10 grams of egg per day (about 1/6th of a large egg) doubled cardiovascular risk”.[13] Furthermore, “egg consumption also increases the risk of diabetes[14], and of congestive heart failure.[15]

Speaking of Smoking

Dr. Spence et al. in a study conducted at vascular prevention clinics found that egg yolk consumption had a similar effect on carotid atherosclerosis as smoking[16]. And this was independent of other variables. “Furthermore, the effect of egg consumption and smoking appeared to be additive[17]. In other words, “egg consumption alone (has) approximately 60% of the effect of smoking alone.[18]

Choline and Oxidative Stress

There is another constituent in eggs that has more recently been shown to have harmful effects on our overall vascular health – phosphatidylcholine. When we consume dietary choline it is converted by intestinal bacteria into something called trimethylamine. This in turn is oxidized in the liver to trimethylamine n-oxide (TMAO). A 2011 study[19] showed “that TMAO was pro-atherosclerotic . . . and was associated with vascular disease in patients.”[20] And these same researchers confirmed that intestinal flora plays a major role in converting choline to TMAO. Furthermore, it also showed patients who underwent coronary angiography, and had higher levels of TMAO, were at risk 2.5x greater for a cardiovascular event.[21]

Again, this video by Dr. Greger, explains further the relationship between choline and TMAO. Interestingly, it also draws a link to certain forms of cancer like prostate cancer. Ironically, the egg industry actually boasts about choline content in eggs citing its importance for brain function. In fact, they promote choline despite being aware of the cancer data.

So what actually happens after one eats a meal high in dietary cholesterol? It “increases LDL oxidation by nearly 40%[22][23]. Also, high dietary cholesterol can inhibit proper endothelial function for hours after ingestion and likely through oxidative stress[24][25]. The endothelium is cells that form the interior lining in blood and lymphatic vessels. It functions as an interface between the circulating blood and the vessel wall.

What About Protein?

It seems that every food company out there touts the protein content in their particular brand or food. One might think, based on the endless advertising schemes, our society suffers from protein deficiency and not the unprecedented rates of obesity, cancer, diabetes and cardiovascular diseases. There is no coordination or concern about how much daily protein we are getting in aggregate. Each food marketer is only interested in selling the protein virtues of the particular product they are paid to promote. The messaging, therefore, ends up leaving consumers to wonder if they are getting enough protein rather than too much.

While protein is essential in our diets, there is a balance between excessive and adequate. In other words, you can get too much of a good thing! IGF-1 (insulin growth factor) is a hormone in the blood that regulates the replenishment of old and dying cells with new ones in our body. Excessive protein consumption over time can elevate IGF-1 to abnormally high levels and promote cellular growth exceeding our natural requirements. Elevated levels of IGF-1 has been linked to various forms of cancer. The following two videos by Dr. Michael Greger explain the purpose and dangers of IGF-1 and how to prevent IGF-1 from increasing our risk factor.

Diets rich in animal-based proteins can cause something called metabolic acidosis. The body’s response to this is to counter the increased acidity level in the body to make it more alkaline – it will either draw calcium from our diet and/or our bones diminishing the returns of calcium intake and storage. And this excess dietary acid can lead to bone loss and osteoporosis[26].

Then There's The "Case" for Egg Whites

As it relates to eggs, some nutritionists will concede that it is just the egg yolk that should be avoided despite the industry propagating the myth that cholesterol in eggs is harmless. Nutritionists will advocate, however, for the consumption of egg whites because it is almost all protein. However, are egg whites harmless and is all protein created equal?

Egg whites are high in a sulphur-containing amino acid called methionine. Methionine is metabolized in the body into homocysteine. And high levels of homocysteine can lead to damage to the endothelium and thus cardiovascular disease, congestive heart failure and stroke. It can also lead to macular degeneration and possibly even Alzheimer’s disease.[27]

As well, sulfur-containing amino acids are known to be toxic to the tissues of the intestine, and to have a negative impact on the human colon possibly causing ulcerative colitis.[28]

Nutritional Epidemiology and the Media

Given the concerns around industry propaganda and methodology, it gives rise to reasonable concerns and suspicion about many nutrition studies. One can walk through many institutions of higher learning and find newly built wings and research facilities bearing the names of wealthy, corporate food donors. A recent article in The Atlantic gives many researchers and public educators concern that “corporate backers can be given a great deal of power and latitude, selecting the specific kinds of studies, materials, and techniques to be used in exchange for their funding”.

But co-opting independent research facilities and universities is only part of the problem. The media also has some culpability as they are the vehicle through which misinformation can spread.

The Dangers of Click Rate

Headlines can often be misleading or tell just a fraction of the story. The media’s complicity in its desire to publish sensationalist headlines underwritten by flawed research methodology cannot be understated. “The eagerness of the media to report benefits of egg consumption suggests that such stories are of interest because they are surprising reversals of accepted wisdom.”[29], says Dr. Spence.

There are many others frustrated with the current state of nutritional epidemiology and the media as well. Dr. Vinay Prasad, an Oregon oncologist and medical policy researcher, recently caused a stir on social media with this tweet: “A team of scientists prove the human thirst for bullshit science and medicine news is unquenchable”. This was in response to a study on safe levels of alcohol consumption, published in The Lancet and widely disseminated by media outlets like CNN.

Dr. Prasad said in this article that, “It is a field with fundamental structural problems that make drawing conclusions from it incredibly unreliable”. He went on to critique those studies that depend on people who fill out questionnaires reporting what they eat and drink (like this one on egg consumption). Dr. Prasad says, “the data can be flawed if people can't remember or don't accurately record what they ate or drank. And the research also depends on people telling the truth”. The most common of these questionnaires are called FFQ’s (Food Frequency Questionnaires). Many studies promoting egg consumption have relied on this method. FiveThirtyEight.com recently demonstrated the deep flaws inherent in the use of FFQ's.

Dr. Prasad believes that researchers analyze the data searching for links with health outcomes. And, as a result, “the studies often end up in the news under contradictory headlines”.

Unfortunately, the media will pick up on and disseminate those studies that appear to be “contradictory”. Sadly, research that offers nothing new or simply validates long-held understanding or knowledge don’t make headlines. And almost all news media these days are profit-driven. Simply put…provocative headlines draw advertising revenue.

Power and Politics

Whether it is egg industry propaganda, or sensationalist media reports declaring some new reversal of conventional wisdom based on questionable methodology or contrived study design, the information landscape can be exceedingly difficult to navigate. The average consumer certainly doesn’t have the time to delve deep into these issues to determine the preponderance of the evidence.

What the egg industry does is not unlike what the tobacco industry did during the 1950’s, 60’s and 70’s regarding lung disease. And it is not dissimilar to the misinformation campaigns employed by the sugar industry in the 1960’s to distract from their products impact on heart health. These are multi-billion dollar industries that have more to lose than anybody else if people stop consuming their harmful products or even reduce their consumption. In 2016, it was reported in this L.A. Times article that the American Egg Board, (which is a federally supervised trade group), launched a secret campaign to thwart a San Francisco start-up called Just Mayo - "a hot investment for Silicon Valley venture capitalists and an avatar for alternatives to industrial (animal) agriculture". An investigation had found that the AEB's "monitoring of a specific company and product and its attempt to undermine them were inappropriate and exceeded the 1976 bylaws that govern the 18-member board, which is appointed by the secretary of Agriculture and uses the $20 million in annual fees it collects from large-scale producers to support research and promote the egg industry".

Dr. John McDougall has noted that,  "in the past two decades, the American Egg Board and the Egg Nutrition Center have become increasingly active in using research to increase demand for eggs. Of the 41 studies on dietary cholesterol included in a 1992 meta-analysis, 29% were paid for by industry, mainly the egg industry. Nine years later, in a 2001 meta-analysis, that figure had risen to 41%. Two decades later, in a 2013 review, the figure was 92%. The food industry now dominates research on dietary cholesterol".

The egg industry has very powerful lobbies that influence legislators. They infiltrate health panels and government organizations tasked with allocating research funding. And an industry the size of the egg industry has the financial resources to deploy effective public relations and advertising campaigns with unparalleled reach to convince you to buy their product.

The sad reality is that dietary food guides and recommendations issued by government today are generally not based on truly independent nutrition research but are a result of negotiation between the food industry and the agencies tasked with issuing these guidelines. These government agencies (paid for and funded by taxpayers) routinely fall victim to regulatory capture. Agencies like the FDA and the USDA serve at the behest of the industry they were mandated to regulate and monitor instead of the public they have sworn an oath to protect and inform.

Nutritionism and Unique Positioning

Marion Nestle, a PhD in microbiology at the University of California Berkeley and Paulette Goddard professor of nutrition, food studies and public health, emerita, New York University, wrote in The Journal of the American Medical Association, “is it really true that food companies deliberately set out to manipulate research in their favor? Yes, it is, and the practice continues.” She too refers to the tactics of the sugar industry some decades ago in which they employed a diversionary tactic to point a finger at another risk factor: saturated fats (sound familiar?).

Dr. Nestle also argues that food companies seek to influence a debate by focusing on a methodology known as “nutritionism” (or unique positioning). Nutritionism is defined by Wikipedia as “a paradigm that assumes that it is the scientifically identified nutrients in foods that determine the value of individual food stuffs in the diet.” Nutritionism is inherently misleading. One must look at all of the ingredients in a particular food to determine their aggregate value. In other words, ingesting protein is fine, however, if the cost of doing so also results in you consuming copious amounts of bad elements like cholesterol or saturated fat, this will dramatically alter the inherent value of that food.

Dr. Nestle goes on to say, “food company sponsorship, whether or not intentionally manipulative, undermines public trust in nutrition science, contributes to public confusion about what to eat, and compromises Dietary Guidelines in ways that are not in the best interest of public health.”

In Conclusion

So the next time you read how “eggs are healthy”, or “they reduce the risk of heart disease”, or eggs have “no negative impact on those with type 2 diabetes or pre-diabetes”, take it with a grain of salt (figuratively speaking of course!). In fact, these claims are insidious as millions of people may throw caution to the wind and put their health at risk based on a single headline.

Therefore, we strongly encourage everyone to leave eggs off their plates entirely. While we understand that that may be hard for some people, there are some truly amazing egg alternatives on the market worth considering. There are also some great recipes that either replace or simulate eggs that are delicious, considerably healthier and provide much needed fibre - the one ingredient, ironically, most people are deficient in and that no animal product contains, including eggs.

Footnotes

1. Spence JD, Jenkins DJ, Davignon J, Dietary cholesterol and egg yolks: Not for patients at risk of vascular disease. Can J Cardio 2010;26:e336-6
2. Spence JD, Submission to the Office of Disease Prevention and Health Promotion on Recommendations regarding dietary cholesterol. March 2015
3. Spence JD, Submission to the Office of Disease Prevention and Health Promotion on Recommendations regarding dietary cholesterol. March 2015
4. Spence JD, Submission to the Office of Disease Prevention and Health Promotion on Recommendations regarding dietary cholesterol. March 2015
5. Spence JD, Jenkins DJ, Devignon J, Dietary cholesterol and egg yolks: Not for patients at risk of vascular disease. Can J Card 2010;26:e336-9
6. Dubois C, Armand M, Mekki N. Portugal H, Paul AM, Bernard PM, et al. Effects of increasing amounts of dietary cholesterol on pospandrial lipemia and lipoproteins in human subjects. J Lipid Res 1994;35;1993-2007
7. Liese Ad, Weis KE, Schulz M, Tooze JA. Food intake patterns associated with incident type 2 diabetes: The Insulin Resistance Atherosclerosis Study. Diabetes Care2009;32:263-8
8. Djousse L, Gaziano JM, Buring JE, Lee IM. Egg consumption and risk of type 2 diabetes in men and women. Diabetes Care2009;32:295-300
9. Subramanian S, Han CY, Chiba T, et al. Dietary cholesterol worsens adipost tissue macrophage accumulation and atherosclerosis in obese LDL receptor-deficient mice. Arterioscler Thromb Vasc Biol 2008;28-685-91
10. Rull A, Rodriguez F, Aragones G, et al. Hepatic monocyte chemoattractant protein-1 is upregulated by dietary cholesterol and contributes to liver steatosis. Cytokine 2009;48:273-9
11. FieldingCJ, Havel RJ, Todd KM, Yeo KE, Schloetter MC, Weinberg V, Frost PH. Effects of dietary cholesterol and fat saturation on plasma lipoproteins in an ethnically diverse population of healthy young men. J Clin Invest 1995;95:611-8
12. Spence JD, Jenkins DJ, Davignon J. Dietary cholesterol and egg yolks: Not for patients at risk of vascular disease. Can J Cardio 2010;26:e336-e339
13. Spence JD, Submission to the Office of Disease Prevention and Health Promotion, Recommendations regarding dietary cholesterol. March 2015
14. Djousse L, Gaziano JM, Buring JE, Lee IM. Egg consumption and risk of type 2 diabetes in men and women. Diabetes Care 2009;32:295-300
15. Djousse L, Gaziano JM. Egg consumption and risk of heart failure in the Physicians’ Health Study. Circulation 2008;117:512-6
16. Spence JD, Jenkins DJ, Davignon J. Egg yolk consumption and carotid plaque. Atherosclerosis2012;224 (2):469-73
17. Spence JD, Jenkinds DJA, Davignon J. Egg yolk consumption, smoking and carotid plaque: Reply to Letter to the Editor. Atherosclerosis. In press 2012
18. Spence JD, Submission to the Office of Disease Prevention and Health Promotion on Recommendations regarding dietary cholesterol. March 2015
19. Wang Z, Klipfell E, Bennet BJ, Koeth R, Levison BS, Dugar B, Feldstein AE, Britt EB, Fu X, Chung Y, Wu Y, Schauer P, Smith JD, Allayee H, Tang WH, DiDonato JA, Lusis AJ, Hazen SL. Gut flora metablosim of phosphatidylcholine promotes cardiovascular disease. Nature2011;472:57-63
20. Spence JD, Submission to the Office of Disease Prevention and Health Promotion on Recommendations regarding dietary cholesterol. March 2015
21. Tang WHW, Wang Z, Levinson BS, Koeth RA, Britt EB, Fu X, Wu Y, Hazen SL. Intestinal Microbiota Metabolism of Phosphatidylcholine and Incident Cardiac Risks. New England Journal of Medicine2013;368:1575-84
22. Levy Y, Maor I, Presser D, Aviram M. Consumption of eggs with meals increases the susceptibility of human palasma and low-density lipoprotein to lipid preoxidation. Ann Nutr Metab1996;40:243-51
23. Schwab US, Ausman LM, Vogel S, Li Z, Lammi-Keefe CJ, Goldin BR, Ordovas JM, Schaefer EJ, Lichtenstein AH. Dietary cholesterol increases the susceptibility of low density lipoprotein to oxidative modification. Atherosclerosis2000;149:83-90
24. Terasaka N, Yu S, Evan-Charvet L, Wang N, Mzhavia N, Langlois R, Pagler T, Li R, Welch CL, Goldber IJ, Tall AR. ABCG1 and HDL protect against endothelial dysfunction in mice fed a high-cholesterol diet. J Clin Invest2008;118:3701-13
25. Plotnick GD, Corretti MC, Vogel RA, Hesslink R, Jr., Wise JA. Effect of supplemental phytonutrients on impairment of the flow-mediated brachial artery vasoactivity after a single high-fat meal. J Am Coll Cardiol2003;41:1744-9
26. Remer T, Influence of diet on acid-base balance. Semin Dial. 2000 Jul-Aug;13(4): 221-6
27. Troen AM.  The atherogenic effect of excess methionine intake. Proc Natl Acad Sci USA. 2003;Dec 9;100(25):15089-94
28. Levine J, Fecal hydrogen sulfide production in ulcerative colitis. Am J Gastroenterol. 1998:Jan;93(1):83-7
29. Spence JD, Jenkinds DJ, Devignon J, Dietary cholesterol and egg yolks: Not for patients at risk of vascular disease. Can J Cardio 2010;26;e336-9