Eggs are one of the most controversial foods out there. Even among dietitians, there’s a great polarization of opinions when it comes to the health implications of eating eggs. Some say eggs are harmful and should be avoided, others say the exact opposite.
Whenever someone asks me if a food is healthy or not, I like to use the traffic light analogy. Green is good, yellow is neutral or unknown, and red is bad. The current evidence suggests that eggs fall into the yellow-red area.
If this is the case, then why do some people think eggs are healthy? Well, there are a few things at play here. First and foremost, the egg industry spends millions of dollars on research and marketing to minimize the negative and overemphasize any positive health implications associated with eating eggs. The American Egg Board (AEB) is a government checkoff program overseen by the United States Department of Agriculture (USDA). Its purpose is to “establish, finance, and execute coordinated programs, on research, education and promotion—all geared to drive demand for eggs and egg products.” You may have heard their slogan, “The Incredible, Edible Egg”.
According to their own annual report, The American Egg Board and their sister group, the Egg Nutrition Center, spend millions of dollars each year on research, which then serves as “the underpinning of the AEB’s marketing”. This “research” is meant to do one of two things: promote eggs as healthy, or contradict any other evidence suggesting that eggs are harmful. These studies then make their way to the public through the mainstream media, unaware dietitians/nutritionists/doctors, and health websites where a pro-egg message fits their agenda. Most of these outlets fail to realize that industry-funded studies should be taken with a grain of salt, or better yet, not considered at all.
As Marion Nestle, a nutrition professor who literally wrote the book on food politics, would say, industry-funded research is more about marketing than it is about science. I agree. Especially since industry-funded studies produce results that overwhelmingly favor the sponsor’s product (1-2). This is no coincidence. These biased studies “muddy the water” and dilute out independently sponsored, unbiased research, leaving us in what appears to be a pool of conflicting data. But when we filter out the biased research, the water becomes much clearer and we’re able to make uninfluenced conclusions regarding the data.
So, just like we wouldn’t use research funded by the tobacco industry when trying to determine if cigarettes are healthy, or studies conducted by Coca-Cola when looking at the health implications of sugar-sweetened beverages, we aren’t going to use egg industry research when trying to determine if eggs are healthy or not. Now, back to the question at hand: are eggs healthy?
Eggs and Cardiovascular Disease (CVD)
It is well established that a diet rich in saturated and trans fat (mostly from meat, dairy, and desserts) raises cholesterol and increases our risk of CVD. The big question with eggs is whether consuming them (and therefore a high amount of dietary cholesterol, at about 200mg per egg) has the same effect.
Dietary cholesterol, including from eggs, does indeed raise total and LDL cholesterol, but to a lesser extent than saturated and trans fats (that doesn’t mean dietary cholesterol or eggs are off the hook though). Interventional studies clearly show that increasing dietary cholesterol and/or egg consumption leads to an increase in total and LDL cholesterol, as well as LDL cholesterol oxidation, none of which is good (3-7). One study suggests that consuming one additional egg per day will increase LDL cholesterol by nearly four points (8). Metabolic kitchen studies, where all other dietary factors can be controlled for, show that adding cholesterol to one’s diet increases blood cholesterol levels (9). These kinds of studies also show that restricting cholesterol in one’s diet reduces blood cholesterol levels (10). Based on this data, it’s safe to say that in general, adding eggs/cholesterol to our diet will increase total and LDL cholesterol (which we don’t want), and removing eggs/cholesterol from our diet will lower total and LDL cholesterol (which we do want).
It should be noted, however, that the extent to which dietary cholesterol and/or eggs raises blood cholesterol appears to vary from person to person. Some people appear to be “hyper” responders, in that their cholesterol levels greatly increase in response to dietary cholesterol. While others appear to be “hypo” responders, in that their cholesterol does not increase much in response to dietary cholesterol. Despite these individual variations, the overall picture shows that egg/cholesterol consumption is detrimental to blood cholesterol levels.
Eating eggs also appears to inhibit blood flow. One study compared eggs to oatmeal and found that egg consumption acutely reduced blood flow, whereas oatmeal consumption improved it (11). This study also found that daily oatmeal consumption over six weeks significantly lowered total and LDL cholesterol, whereas daily egg consumption did not. Some of these same researchers conducted a similar study a few years later. This time around they found that egg consumption had no acute effect on blood vessel function, but that was only when compared to eating a sausage and cheese breakfast sandwich! They also found that after six weeks, consuming an egg substitute, compared to actual eggs, resulted in significantly improved blood vessel function, lower total cholesterol, and lower LDL cholesterol (12). Both of these studies found that not eating eggs was healthier than eating eggs, yet neither of them came to that conclusion. Why? Because they were both funded by the egg industry. Whoops. These two studies are rare examples of industry-funded studies that find the sponsor’s product to be detrimental. Yet the authors, aware of where their research dollars are coming from, worded their conclusion in a way that minimized the results. Instead of concluding that “oatmeal and egg substitutes are far healthier than actual eggs”, the message was, “egg consumption is non-detrimental”.
The egg industry has long boasted that eggs are a good source of choline, which they are. But it now appears that eating a lot of choline may not be such a good thing. A handful of recent studies have shown that dietary choline (particularly from eggs, meat, dairy, and seafood) can be metabolized by certain gut bacteria, which go on to produce a compound called trimethylamine (TMA). TMA is then converted into trimethylamine-N-oxide (TMAO) by the liver. TMAO is known to enhance the development of atherosclerosis (plaque buildup) in our blood vessels, which is a major cause of heart attacks and strokes (13). More research is needed to further explore the implications of this, but it appears to be yet another pathway in which eggs may negatively impact our cardiovascular health.
We know that egg consumption raises cholesterol levels (although this varies from person to person), and it has also been shown that egg consumption reduces blood flow and may promote plaque buildup through the TMAO pathway—but do these changes in cardiovascular risk factors lead to more cardiovascular disease? Large, long-term, population-based studies are used to show associations between a certain food and disease risk over time. However, these studies can’t prove cause and effect, and are more likely to be influenced by confounding factors, so we need to tread cautiously when interpreting their results.
If we look at observational studies regarding egg consumption and CVD, we find mixed results. Some studies show that egg consumption is associated with CVD, while others do not. Despite these mixed results, two consistent trends emerge across the data. The first is that egg consumption does appear to be associated with CVD in a dose-dependent manner (14-17). In other words, occasional egg consumption is not associated with CVD risk, but as the number of eggs consumed increases, so does the risk. At some point, this association becomes significant, especially for heart failure. The second trend among these studies, is that the association between egg consumption and CVD is much stronger in high-risk subgroups, such as people with diabetes (17-18).
In summary, the cholesterol in eggs can significantly raise blood cholesterol levels, although the extent to which this occurs varies from person to person. This effect is not as significant when compared to saturated or trans-fat, but it still is worth taking into consideration (especially in high-risk populations). Egg consumption also appears to acutely inhibit blood flow and may further contribute to CVD through the choline/TMAO pathway. Large, population-based studies suggest that occasional egg consumption in healthy individuals may not increase CVD risk, but as consumption increases, so does the risk. Individuals with a history of CVD or any CVD risk factors should avoid eggs, as they appear to be an especially vulnerable population. Based on this data, eggs fall into the yellow-red area of the traffic light when it comes to cardiovascular disease.
Eggs and Type-2 Diabetes
When looking at egg consumption and type-2 diabetes, we are limited to mostly observational studies. Although some studies have found no link between egg consumption and type-2 diabetes, the overall evidence does suggest that egg consumption is associated with type-2 diabetes, placing them in the yellow-red area of the traffic light (19-23). Even after controlling for potential confounding factors, these studies find that people eating the most eggs have a 2-3 times greater risk of type-2 diabetes, compared to people eating the least. Some studies have also shown that egg and cholesterol consumption is linked to gestational diabetes, so pregnant women at risk for gestational diabetes should probably avoid eggs (24-25).
These associations could be due to something called reverse causality. Maybe eating eggs doesn’t lead to type-2 and gestational diabetes, but rather having type-2 or gestational diabetes leads to eating more eggs. This is possible, but why risk it? Given the cardiovascular and cancer implications (which we’ll discuss next) of eating eggs, a healthier breakfast option would be oatmeal.
Eggs and Cancer
Similar to egg consumption and diabetes, there is mixed data when it comes to egg consumption and cancer risk. However, the overall data suggests a link to certain types of cancer, which again puts eggs in the yellow-red area on the traffic light. Studies have found egg consumption to be associated with an increased risk of lethal prostate cancer, prostate cancer progression and recurrence, colorectal cancer, colorectal cancer mortality, and breast cancer (26-31). The same choline/TMAO pathway that contributes to atherosclerosis may also promote cancer development and progression, especially for prostate and colorectal cancers (32-35). The data also suggests a link between dietary cholesterol and pancreatic cancer (36-38). These studies show associations, not causation, but given the potential risk, a healthier option would again be oatmeal.
Do Eggs Offer Any Health Benefits?
It’s always worth looking at the risk/benefit of a food item. Although eggs appear detrimental to our cardiovascular health, and may promote type-2 diabetes and certain cancers, do they offer any health benefits?
The evidence suggests that greater egg consumption may increase HDL (good) cholesterol. Yet more and more research suggests that the role HDL cholesterol plays in CVD is minor, and that reducing LDL cholesterol (which increases with egg consumption) should be the main focus. An increase in HDL cholesterol (especially in light of an increase in LDL cholesterol) is not a good reason to eat eggs.
Some studies show that egg consumption may help with weight loss and blood sugar control, but these are mostly industry-funded studies that include co-interventions, such as calorie restriction or exercise. One observational study found that people eating higher amounts of eggs had a lower risk of stroke, but this appears to be an outlier and warrants further investigation before making any conclusions.
The Egg Nutrition Center, as well as other pro-egg websites/articles, point to individual nutrients that make eggs healthy. Here are the most common nutrients mentioned:
- Choline: We’ve already discussed why this is probably not a good thing.
- Protein: Most Americans already consume twice as much protein as they need; with most of it coming from animal sources. People tend to be healthier when they reduce the amount of animal protein in their diet and replace it with protein from plant sources.
- Vitamin D: Most people aren’t getting enough vitamin D. This is largely because most people aren’t getting outside enough (we can make vitamin D from the sun). Although eggs contain some vitamin D, you would need to eat 15 eggs per day to reach the recommended daily amount for adults. Getting out in the sun for 10-15 minutes, or taking a supplement during the winter months would be much healthier options.
- Vitamin B12: Eggs do contain B12, however our absorption of B12 from eggs is extremely poor (39). Fortified plant-based foods and/or supplements is the preferred source of B12.
- Lutein: Lutein is a yellow pigment that serves as an antioxidant, particularly in our eyes. Eggs are often considered a “good source” of lutein, but this is extremely misleading. Eggs do contain a small amount of lutein, but there are literally dozens of foods that contain far more. Dark, leafy greens are by far the best source. Pound-for-pound, kale contains 36 times more lutein than eggs. A couple bites of cooked spinach contains more lutein than a whole carton of eggs. Heck, even microwave popcorn has more lutein in it than eggs. So, no, eggs are not a good source of lutein.
From a pure health standpoint, eggs appear detrimental to our cardiovascular health, and may promote type-2 diabetes and certain cancers. Eggs contain nutrients that most Americans should be trying to avoid, such as cholesterol, animal protein, and saturated fat, and are not a good source of any health-promoting nutrients. For these reasons, eggs fall into the yellow-red area of the traffic light. Their consumption should be avoided, or at least, limited.
What About the Animals?
I adopted a plant-based diet to improve my own personal health. But in this process, I was exposed to the numerous other reasons we should reconsider the animal products on our plate. I’m about to share information about egg production that is graphic and disturbing, but as informed consumers, it’s something we should be aware of before choosing to (or not to) consume a product.
Egg industry breeding operations kill half of all chicks within the first day of hatching. Because only females lay eggs, male chicks are deemed “useless” to the egg industry. Every year, in a processed called “chick culling”, billions of male chicks are killed on the first day of their life. Common industry practices for killing these baby chicks include suffocation, manually breaking their necks, or tossing them alive into a high-speed grinder. This occurs throughout the industry, even on operations that produce organic, cage-free, or free-range eggs.
Although the males are killed shortly after hatching, the females are also treated in a cruel way. Shortly after hatching, most females will be “debeaked”, a painful process that the industry uses to keep birds from pecking each other to death because of the stressful and overcrowded living conditions they are provided. Most hens will be crammed into cages so small they can’t spread their wings. Many develop foot wounds from constantly standing on the wire bottoms.
Labels like cage-free, free-range, and organic offer minor improvements, but fall drastically short of anything that most people would deem acceptable. Hens on cage-free operations are kept in large, crowded warehouses where the floor is covered in feces and fresh air is not a requirement. Free-range hens, by definition, only need to be “offered” access to an outdoor enclosure. The size of this enclosure and the number of exits is not specified, so most of these birds, despite the free-range label, will never set foot outside. An organic label means the hens are fed an organic diet. It also mandates that the hens can’t be in cages and need to be “offered” access to an outdoor enclosure, but again, there are no further specifications.
On all egg-laying operations, hens, from birth to death, are exploited for their bodies in ways that would infuriate any feminist. The process of laying an egg is extremely taxing on their bodies. Selective breeding has resulted in chickens that produce an egg once a day, as opposed to once a week, or once a month for most other breeds. When their production drops, after roughly two years, hens are considered “spent” and are sent to slaughter (two years is just a fraction of their natural lifespan). Their bodies are often so emaciated that they are considered unfit for human consumption, and are therefore ground up to make pet food.
If you find these practices disturbing, then you may want to consider leaving eggs off your plate. The good news is that eating egg-free is becoming easier and easier. You can make breakfast scrambles or sandwiches using tofu. Companies like Follow Your Heart and Hampton Creek make a wide variety of egg-less products. Or you can stick with naturally egg-free meals, like oatmeal, avocado toast, fruit and vegetable smoothies, or acai bowls. There are also plenty of ways to replace eggs when baking. Pureed banana, applesauce, pumpkin, or a “flax-egg”, are all healthier baking alternatives to eggs. Give them a try!
Eggs are, and will likely continue to be, a controversial food. Yet this controversy is largely the result of egg industry push-back when faced with evidence suggesting that eggs are detrimental to human health. If you read an article or study stating that eggs are healthy, I would encourage you to look at who wrote it and check their credentials/affiliations. Also, look at the sources they cite and where the funding came from. You can almost always follow the money back to the source—the egg industry.
This post has shed light on the messy world of food politics, the overall evidence as it pertains to egg consumption and health, and the animal welfare issues that come with egg production. I hope it helps you make a more informed decision about your breakfast.
Disclaimer: I receive no funding or support from any food company. Nor do I have any stock in egg replacement companies.
- Corporate Funding of Food and Nutrition ResearchScience or Marketing?
- Food Industry Funding of Nutrition ResearchThe Relevance of History for Current Debates
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