Disease Proof

Comparing eggs to cigarettes

Eggs are one of the most concentrated sources of cholesterol in the American diet, but how much does that dietary cholesterol actually impact blood cholesterol and heart disease risk? A recent study investigated egg consumption and cigarette smoking in relation to atherosclerotic plaque in the carotid artery – headlines proclaimed “Egg yolks almost as bad as smoking.” Is this a valid assessment of the data? Let’s look at all the science on eggs and heart disease and find out.

Egg. Flickr: stevendepolo

First, how much does the dietary cholesterol found in egg yolks impact blood cholesterol?
Many studies have investigated this, and the consensus is that dietary cholesterol does raise serum total cholesterol somewhat, but to a very small degree compared with dietary saturated or trans fat.1, 2 Dietary cholesterol elevates serum LDL and HDL cholesterol; meta-analysis of several studies showed that the dietary cholesterol from eggs is associated with an increase in the ratio of total to HDL (“good”) cholesterol, which is an indicator of increased cardiovascular risk. These authors reported that the cholesterol from 3-4 eggs per week would elevate total:HDL ratio an amount estimated to translate into 2.1% increase in heart attack risk.3 A small increase in risk, but still an increase.

Are people that eat more eggs more likely to have heart attacks and strokes?
Because of eggs’ high cholesterol content, many observational studies have relied on egg consumption as a marker of cholesterol intake. These previous studies have not shown a clear increase in heart attack, stroke, or death from cardiovascular disease in those who eat the most eggs. The Physicians’ Health Study, however, reported a 23% increase in death risk in those who ate more than one egg/day.4 Interestingly, these studies have consistently found that diabetics (who are already at increased risk) who eat more eggs do increase their risk – by a lot. The Nurses’ Health Study, Health Professionals Follow-up Study, and Physicians’ Health Study reported that diabetics who eat more than one egg/day double their cardiovascular disease or death risk compared to diabetics that ate less than one egg per week.5,6 A Greek study of diabetics reported a 5-fold increase in cardiovascular death risk in those eating one egg/day or more.7 Collectively from these data, we can conclude that eggs are likely only to be dangerous in large quantities (more than one egg/day) for healthy individuals, but could be more problematic for populations at risk of cardiovascular disease, such as diabetics. Interestingly, eating 5 eggs/week or more is also associated with an increased risk of developing type 2 diabetes (not to mention prostate cancer).8,9

In contrast, cigarette smoking is very clearly linked to heart disease, stroke, and death. Cigarette smoking is estimated to cause over 400,000 deaths per year in the U.S. alone, one-third of which are related to cardiovascular disease.10

The new study – eggs, cigarettes, and carotid plaque area
Twelve-hundred patients answered questionnaires on their diet and lifestyle, and had ultrasound-based measurements of their total carotid artery plaque area, a strong predictor of future cardiovascular events.11 The authors found similar steep increases in plaque area with increasing “pack-years” of smoking (number of packs/day multiplied by number of years of smoking) and “egg-yolk years” (number of egg yolks/week multiplied by number of years consumed). Importantly, egg yolk consumption and smoking history were not significantly correlated – this means that the people that ate the most eggs were not necessarily the ones who smoked the most. Since carotid plaque area increased more steeply with egg-yolk years and pack-years than with age, the authors concluded that both factors accelerate plaque development. The group with the greatest number of egg-yolk years (200 or more) had plaque development equivalent to 2/3 that of those with the greatest number of pack-years of smoking (more than 40). For example, the data suggests that someone who had eaten 5 eggs/week for 40 years would have 2/3 the amount of plaque as someone who smoked one pack of cigarettes a day for 40 years, other factors being equal.

In addition, they found that subjects eating more than 3 eggs/week (compared to less than 2 eggs/week) had significantly more carotid plaque area – even after statistical controls for a number of factors, including serum cholesterol. This indicates that eggs may increase atherosclerotic plaque development in ways unrelated to elevating blood cholesterol.

The bottom line on eggs
Eggs do contribute some vitamins and minerals and are likely one of the better choices when it comes to animal foods.12 However, there is no nutritional advantage for getting vitamin A/ carotenoids, folate, minerals, etc. from eggs rather than from plant foods. Plus, eggs are extremely rich in animal protein, which is not health-promoting. Although previous studies have not seen increased cardiovascular risk in individuals eating up to one egg/day, the new study has identified increased carotid artery plaque in individuals eating 3 eggs/week or more. Taking all this research into account, and comparing to the sobering statistics on cigarette smoking, “eggs are almost as bad as smoking” is probably an overstatement; however, eggs may be more harmful to cardiovascular health than the earlier studies suggested; larger, long-term studies will help to determine the magnitude of risk associated with eggs. If you are at risk of cardiovascular disease, the potential risks of egg consumption must be considered. The associations of eggs with diabetes and prostate cancer must also be considered.


Those with diabetes or cardiovascular disease or at high risk for these conditions (overweight or high cholesterol) should not eat eggs, though 1-2 eggs per week in a slim, healthy individual who is not eating many other animal products is unlikely to be harmful.

 

Image credit: Flickr - stevendepolo

References:

1. Clarke R, Frost C, Collins R, et al. Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies. BMJ 1997;314:112-117.
2. Howell WH, McNamara DJ, Tosca MA, et al. Plasma lipid and lipoprotein responses to dietary fat and cholesterol: a meta-analysis. Am J Clin Nutr 1997;65:1747-1764.
3. Weggemans RM, Zock PL, Katan MB. Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans: a meta-analysis. Am J Clin Nutr 2001;73:885-891.
4. Djousse L, Gaziano JM. Egg consumption in relation to cardiovascular disease and mortality: the Physicians' Health Study. Am J Clin Nutr 2008;87:964-969.
5. Qureshi AI, Suri FK, Ahmed S, et al. Regular egg consumption does not increase the risk of stroke and cardiovascular diseases. Med Sci Monit 2007;13:CR1-8.
6. Hu FB, Stampfer MJ, Rimm EB, et al. A prospective study of egg consumption and risk of cardiovascular disease in men and women. JAMA 1999;281:1387-1394.
7. Trichopoulou A, Psaltopoulou T, Orfanos P, et al. Diet and physical activity in relation to overall mortality amongst adult diabetics in a general population cohort. J Intern Med 2006;259:583-591.
8. Djousse L, Gaziano JM, Buring JE, et al. Egg consumption and risk of type 2 diabetes in men and women. Diabetes Care 2009;32:295-300.
9. Richman EL, Kenfield SA, Stampfer MJ, et al. Egg, red meat, and poultry intake and risk of lethal prostate cancer in the prostate-specific antigen-era: incidence and survival. Cancer Prev Res (Phila) 2011;4:2110-2121.
10. Roger VL, Go AS, Lloyd-Jones DM, et al. Heart Disease and Stroke Statistics--2012 Update: A Report From the American Heart Association. Circulation 2012;125:e2-e220.
11. Spence JD, Eliasziw M, DiCicco M, et al. Carotid plaque area: a tool for targeting and evaluating vascular preventive therapy. Stroke 2002;33:2916-2922.
12. Applegate E. Introduction: nutritional and functional roles of eggs in the diet. J Am Coll Nutr 2000;19:495S-498S.

 

 

 

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Comments (14) Read through and enter the discussion with the form at the end
NevadaSmith - August 31, 2012 9:17 PM

Okay! So what?
Seems pretty unscientific if you ask me. Surely there are so many variables to be considered.

For instance: egg eaters are more often meat eaters as well and meat eaters also eat refined carbs BUT vegans don't eat eggs or meat and may or may not eat refined carbs. So is it the eggs or is it something else in the diet of the egg eaters that is to blame for this data?

I don't see how you can blame the eggs? I'll bet if these egg eaters ate nothing else except an otherwise healthy nutritarian diet (except for the eggs) the results would be a lot different.

Fairah Epple - September 1, 2012 7:57 AM

Hello Dr. Fuhrman. I'm a health coach studying with IIN and have thoroughly enjoyed your lectures. I believe in the principles of eating nutrient dense whole foods and appreciate all the work you have done to help quantify the nutritional values of so many foods. I enjoy your blog and value your advice, as it usually resonates deeply with my own experience and intuition.

This time, however, I am not so quick to agree with the conclusion that eating eggs may be harmful to one's health, or that [all] eggs are an inferior source of protein. Were the studies based on eating pastured, organic eggs? Is it plausible that people who tend to eat many servings of eggs per week are also eating excessive amounts of meat and the wrong kinds of fats and not enough nutrient dense foods? Put another way, can you state with confidence that, eaten in conjunction with a nutrient dense diet consisting of mostly vegetables and fruits, some whole grains, other sources of healthy proteins and fats, fermented foods, plenty of good water, sunlight and exercise, and other healthy lifestyle factors, the same conclusion would be reached?

Certainly eaten out of proportion to the other elements on your own "Nutritarian" food plate, even pastured organic eggs could pose a threat. But isn't the point of your plate about balance?

mgm - September 1, 2012 11:32 PM

I have to admit I'm getting discouraged. Don't eat eggs. Don't eat meat. Don't eat fish. Don't eat cheese. Don't drink milk. Well, maybe a gram a month of these, but that's all! We say '10%' but we really mean '1%'. Beans are ok, depending on who you ask. Ok so I'll eat some beans everyday. Consume outrageously high amounts of spinach, broccoli, and all those green plants that have plenty of protein, as long as you eat pounds and pounds of them. I've been eating tons of greens for two years now and though the health benefits of them are fine, I am SICK TO DEATH of greens and veggies. And beans. Just completely sick to death of them. The old bad food isn't the least tempting to go back too, either. About three times a year I get to the point where I could care less about any food at all and wish I were an air fern.

Michelle - September 2, 2012 1:57 PM

So: an egg that comes from a hen who runs around in the sun all day eating grass,weeds, legumes, insects and organic flax and wheat... is as bad for me as a cigarette?

Wow.

Joy Lee - September 2, 2012 8:49 PM

Correlation or causation?

Whenever we review the results of such experiments/research we have to pay careful attention if the data shows correlation or causation.

The first poster have nailed it, people who eat a lot of eggs per week quite possibly eat meat and other foods as well. On the other hand, people who avoid eggs are more likely to also avoid meat. Or, another example, someone who has a general awareness for [supposedly] cholesterol rich foods, might avoid all these foods including eggs.


This is similar to that research on how people who take vitamins have a higher chance for X, Y, Z problems.

This might be indeed the case, vitamins could be bad for you, on the other hand someone who does not feel well or have some issues might be more likely to take various supplements compared to someone who feels just fine.

If this idea is still not clear we can look at it like this: lets say there is a drug called HeadacheCure which people take when they have a headache.

A research spanning 20 years involving 100000 people have found that people who take HeadacheCure have a higher chance for headaches. Conclusion: HeadacheCure causes headaches and should be avoided.

The correlation probably exists, as for the causation? The above article does not show it.

peggy kraus - September 3, 2012 6:27 AM

eggs are not healthful fare for humans. high in saturated fat, cholesterol, and animal protein, and low in fiber and other nutrients necessary for good health, eggs should be eaten sparingly, if at all. whether the eggs are organic from chickens that were pasture fed or from chickens that were fed regular chicken food, all eggs contain a great amount of animal protein which creates inflammation in the human body and increases the risk for many life-threatening conditions and diseases.

no eggs for me.

Bad_CRC - September 3, 2012 10:04 AM

"likely one of the better choices when it comes to animal foods"

Well, I don't know of any studies showing a 500% increased risk of CVD death from eating e.g. turkey breast, nor anything showing that it fuels carotid plaque similarly to smoking. I'd say eggs are likely one of the WORST choices.

Joel Fuhrman, M.D. - September 5, 2012 11:01 AM

I don’t make up these studies, just report on them. You guys above just don’t like the findings, but your opinions and frustrations do not change the facts. The researchers are highly trained scientists, account for possible co-factors, and those are the findings. If you love your eggs (and meat) so much go ahead and eat as much as you see fit. But unless you have reviewed all the studies mentioned above in their entirety, you should not be questioning the findings. This is not a popularity contest where opinion matters.
Remember, I do not have one specific diet for everyone, but instead offer guidelines of how to devise the healthiest diet for your needs and individual differences. You can include a wide variety of foods in your diet, but certainly I want animal products limited to much lower amounts and want people to pay particular attention to achieve comprehensive micronutrient adequacy without excess calories, because it saves lives. That means eating a variety of whole plant foods and eating larger amounts of those high nutrient “super foods” that are so protective against cancer. Make sure you read my latest book, Super Immunity. It is not a weight loss book, so it will help answer your expressed confusion about nutrition.
My nutritarian eating style is immensely varied and contains thousands of delicious food options, however it does totally excludes processed or refined foods. Nutritional science is a blessing that affords us many years of a healthier, better and more pleasurable life. Healthy foods are most enjoyable and the foods you prefer the most once you learn this diet-style in depth and practice it long enough.

mgm - September 5, 2012 3:26 PM

Sorry, Dr. Fuhrman. But I have found that people who love veggies, or learn to love veggies, are extrememly intolerant of people who just never get a taste for them. They insist it will eventually happen 'you're just not trying enough variety/ways of fixing them' etc. It's the old 'If I can do it, anyone can do it'(I love it when people declare themselves the standard for everyone's else's experience.). I'm not talking the nutrition science, I'm talking tastes. Think of 'My favorite color is purple, so if you don't like it, you just haven't been looking at it long enough.'People are individuals - they don't all fit in the box. I'm not going to start chowing down meat - I don't have any hang ups with what the studies show.
I have been at this two solid years. I have lost 25 lbs. I have better energy. Alot of my hair color has actually returned, I am getting so many nutrients. My skin is doing very nice things. My blood work is stellar. I could buy stock in Trader Joes, I have downed so many countless pounds of spinach, kale, bok choy. All I'm saying is, none of it has made me love veggies and greens. It HAS however made me sick of them. Am I going to stop? Of course not. But eating for me now is like brushing my teeth or washing the dishes. It's just what you have to do. I just wish once I could hear someone admit that, for SOME people, eating this way, while very good for you, doesn't always turn in to 'you'll learn to love this stuff.' I gave up on that happening a long time ago. I think not allowing for that possbility, no matter how few of us there are out there like this, you are setting those people up. They wonder what they're 'doing wrong' when they aren't doing anything wrong. I'm chasing health, not satisfaction at this point - that's just the way it is. I just accept it.

Kate S. - September 5, 2012 5:08 PM

I'd echo one of Dr Furhman's comments above about the validity of the research. Whenever we hear about results we don't like from diet studies such as these, people discount the findings by saying that they are only observational and there are lots of other confounding factors. Researchers are not stupid! You think they don't know this?! The big prospective studies that are designed to examine diet measure and control for a myriad of such factors. Of course it is possible there is some unmeasured confounding variable but that gets less likely as nutritional science advances and as we see a consistency in findings emerging across studies - as Dr Furhman is noting here with eggs. Almost everything we know about the impact of smoking on human health comes from correlational studies and the negative effect of nicotine was denied for decades because people said "its only correlational".

pattymc - September 5, 2012 10:57 PM

Well said Dr. Fuhrman. Whether or not anyone believes or disbelieves the info it makes no sense to argue about it, take it or leave it. People, you can still eat what you want. I don't care if reports came out saying eggs are the new "power food ", I still wouldn't eat eggs. I used to, but don't anymore. I prefer eating a plant based diet.

JoyLee - September 6, 2012 12:01 AM


"You guys above just don’t like the findings, but your opinions and frustrations do not change the facts."

That is a very strange thing to say. I do not find it frustrating at all nor do I sense any emotional reaction to it.

You are claiming that we have a bias of our own, while the bias is clearly yours. It's called conformity bias which is understood -- I would not expect you to post a research here which might contradict your own conclusions considering the specific purpose of this site.

Again, I am not saying the article is wrong, just that it does not show causation.

In fact if we look at the past 20 years of research about cholesterol, cholesterol from food sources, eggs etc. The conclusions keep changing. One day it's OK to eat that, the next is not.

The reason, is that even with all our knowledge, we still do not know that much about the human body and most of this research just show correlation and not causation.

That is all.

Personally I follow your diet suggested as much as I can because I think there is a lot to it. At the same time I always keep questioning what we consider to be facts, and invert, my opinion remains the same as expressed about this article.

mgm - September 6, 2012 10:08 AM

I would also add that I think someone who adheres to ETL, as I do to a very great extent (I have a Kale is the New Beef t-shirt, take Dr. Fuhrman's vitamins, have read ETL at least 3 times and listened to it on audio countless times during my long commute - so I have literally 'bought in')even though still not liking this healthy food, is to be even more commended than someone whose tastebuds have acheived the miraculous change that he INSISTS will occur. Those of us in this camp would just like a little credit - not so much judgement.

veggielover?? - September 16, 2012 5:00 PM

mgm,
I would just like to say that I had an out of control laughing fit when I read your comments. I, too try to adhere to Dr. Furhman's eating plan because it is one of the healthiest plans out there. Decreasing my risk of cancer, diabetes, cardiovascular disease... for sure. I am convinced of this. However, I echo your sentiments completely! There are days that I cannot STAND the look of anything green. I have tried many of the recipes in the ETL book. This may just be my terrible cooking skills, but no one in my family including me, found them delicious. I would eat the batch for days because no one else would.
I don't dislike vegetables, but I can't say that I am totally disgusted by a slice of non-nutritarian cake, either. When is that supposed to happen?

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