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Nutrition

Are Eggs Healthy or Not? It’s Complicated.

We dug into tons of egg research, but the answer may not be what you're looking for.

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The perfect balance of good taste, diversity of nutrients and affordability makes the humble egg a staple in many of our diets. And with food prices continually rising, expect more people to use eggs as a backbone for more than breakfast. But are you doing your health any favors when you slide that over-easy egg onto your morning toast

Nothing has created quite the back-and-forth in nutrition research as eggs. One moment they’re vilified as a food that can gunk up your arteries, while the next they’re sold as a downright economic superfood. First eggs are bad, then good, then bad again… so, what’s the deal? Should you be chicken to eat eggs?

We took a deep dive into the world of egg research to see if they should win a spot on your weekly grocery list or not. Cue the controversy. 

The sunny side of egg nutrition

Any way you scramble it, eggs are a low-cost nutrient-dense food. Some of their many nutritional highlights include vitamin B12, riboflavin, vitamin A, hard-to-get vitamin D, bone-benefiting phosphorus, and selenium — which is a nutrient linked to improved mood and younger biological age.

A recent study in the Journal of Nutrition found that consuming an average of an egg a day can help prevent a decline in vitamin D levels, though the study was conducted during winter in Australia, which could be a notable factor. 

Eggs are an excellent source of choline, a frequently under-consumed essential nutrient necessary for optimal brain functioning. A single large egg has roughly 35 percent of an average woman’s daily recommended choline intake, and only beef liver provides more gram for gram. Worth noting is that eating eggs can even increase our levels of the antioxidants like lutein and zeaxanthin, both of which play a role in maintaining eye health. Depending on the way the chickens are raised, eggs can also be a source of heart-healthy omega-3 fatty acids.

(Note: Eggs from pasture-fed hens are typically higher in these rockstar fats. Feeding chickens items like flax and algae can also bolster omega-3 levels in the yolk. Remember that there are nutrients in the yolk that you’re not going to get if you just eat egg whites.)

A large egg can supply 6 to 7 grams of protein. Eggs have traditionally been used as the standard of comparison for measuring protein quality in other foods because of their exceptional essential amino acid profile and high digestibility. This is the main reason why a report in the International Journal of Sport Nutrition and Exercise Metabolism suggests that they’re a great option for helping optimize skeletal muscle mass. And for many people, eggs are a go-to way to bump up protein numbers at breakfast — a time that is particularly important for stimulating muscle synthesis. Protein can also help you feel fuller for longer.

But what about all that cholesterol? Each large yolk contains approximately 200 mg of cholesterol, or about 70 percent of the recommended daily limit. This is where the science gets a little scrambled, so to speak.

While many researchers now say that cholesterol in eggs isn’t bad, citing a lack of strong scientific research to link the cholesterol we eat with the cholesterol numbers we see on our blood panel, not all research has let dietary cholesterol and the cholesterol from eggs off the hook when it comes to blood cholesterol numbers and heart health.

Without a doubt, diverse opinions exist regarding eggs. Let’s take a look at some of the scientific literature that supports eating eggs and some that raises a few red flags.  

In defense of eggs

A large study in the American Journal of Clinical Nutrition involving about 177,000 individuals from dozens of countries of various income levels found that higher egg intake levels (more than 7 per week compared with less than one per week) was not associated with worsening blood cholesterol or a higher risk for heart disease and premature death.

A comprehensive review published in the European Journal of Clinical Nutrition showed that an average daily intake of one egg did not raise the chances of developing heart disease or type 2 diabetes in healthy people or heart problems in those with diabetes as long as they were practicing healthy lifestyle habits like eating an overall nutritious diet.

According to one report in Public Health Nutrition, egg consumers are more likely to meet daily requirements for several micronutrients without negatively impacting blood cholesterol numbers. What’s more, the Health Professionals Follow-Up Study (37,851 subjects) and the Nurses’ Health Study (80,082 subjects) reported that eating up to one egg daily did not increase the risk of coronary artery disease or stroke in healthy people.

Some data suggests that the cholesterol buried within the egg yolk is not well absorbed, which is why it would be less likely to have a long-term detrimental impact on blood cholesterol numbers. Egg-derived peptides may even be an ally in the battle against high blood pressure by downplaying an enzyme that triggers a process that leads to artery narrowing. 

And perhaps eggs are a better choice of protein for your ticker than a slab of steak. In a dietary substitution modeling study in the journal Circulation, replacing 100 calories a day from red and processed meat with the same number of calories from fatty fish, yogurt, cheese, or eggs was associated with around a 20 percent lower risk for heart disease.

Compared to other cholesterol-containing foods like red meat and full-fat dairy, eggs contain a relatively lower amount of saturated fat. Each large egg contains about 1.5 grams of saturated fat, while 3 ounces of sirloin steak has about 5 grams. It’s becoming clearer that certain saturated fats in the diet may have a bigger impact on cholesterol levels (including LDL cholesterol) than does dietary cholesterol. Despite some of the rhetoric out there among certain diet factions, elevated low-density lipoprotein (LDL) cholesterol should still be considered a risk factor for cardiovascular disease.

Why people are against eggs

Research published in PLOS Medicine linked eating as little as half an egg per day in people, average age 62 years, to a higher risk of death from all causes and from cardiovascular disease and cancer throughout a 16-year follow-up. Researchers said cholesterol from whole egg consumption accounted for a significant part of the higher mortality risks.

A recent pooled analysis from six prospective U.S. cohorts showed a modest increase (2 percent in absolute risk) in all-cause mortality for each additional half an egg consumed per day. And a research review in Critical Reviews in Food Science and Nutrition that examined the association between various food groups and the risk for heart disease and stroke determined there was a small positive association for egg consumption and heart failure (in contrast, higher intakes of whole grains, vegetables, fruits, seafood and nuts were found beneficial to heart health.)

A recent study involving adults in China found that consuming an average of one or more eggs a day can raise the risk for metabolic syndrome — a cluster of conditions like high blood pressure and blood sugar that raises the risk for heart disease — by 20 percent, compared to consuming an average of half an egg or less a day. Total dietary intake and egg-sourced cholesterol intake were both positively correlated with the odds of developing the Metabolic Syndrome.

Importantly, fried eggs were found to be a bigger risk factor than when eggs were prepared using other methods like hard-boiling. When cooked or processed in direct contact with high heat, like in a frying pan, the cholesterol can become oxidized, and oxidized cholesterol might be a bigger contributor to heart disease progression.

There is also an analysis of 66 studies involving 3,185 participants which revealed that egg consumption (average of 1 per day) can significantly increase total cholesterol: LDL (“bad”) cholesterol and HDL (“good”) cholesterol. But the study did not look into if these changes in cholesterol numbers have any impact on actual cardiovascular disease incidence. 

Ultrasound tests in people at risk for heart disease showed that those who ate more than three eggs a week had increased plaques in their arteries when compared to those who ate two or fewer eggs a week, even after other risks such as smoking were ruled out.

Additionally, a study in the American Journal of Clinical Nutrition found that among older women, as egg consumption increased to three or more times a week, there was a steady increase in diabetes risk that was attributed largely to the cholesterol in the eggs. But being overweight or obese was a bigger risk factor for diabetes than eating eggs. Chinese adults who regularly consumed one or more eggs per day (equivalent to 50 grams) increased their risk of diabetes by 60 percent, according to a British Journal of Nutrition report.

So, are eggs healthy or not?

The unsatisfying answer to this question is that there appears to be no right answer and that each individual’s unique health needs, dietary patterns and genetic makeup play a role in whether eggs are problematic or not. 

What complicates the topic is that many studies have used food frequency questionnaires to gauge egg consumption patterns, which notoriously can introduce errors. People are lousy at accurately reporting what they eat. Possible factors for the different results from different studies include the play of chance, methodological and demographic differences or selection biases that led to the inclusion of some studies but not others in the analyses.

You also have to consider who is funding studies — a chunk of the research downplaying the risks of eggs and cholesterol have been funded by the industry. And the observational studies we are mostly relying on for data about the impact eggs have on human health can’t prove cause and effect. The only true way we would get a definitive answer on the health effects of eggs is if we isolated a bunch of people for several years and fed them the same diets except for eggs and then tracked their health progress. For a variety of reasons including massive cost, this is not feasible. But there are few tidbits we can glean from the wavering research.

It’s likely that healthy individuals with cholesterol levels in the safe range and free of heart disease or diabetes can eat eggs more liberally than people, especially if they are older, that are struggling with keeping their cholesterol at appropriate levels (for instance, LDL cholesterol at 100 or lower) or who are at risk for or diagnosed with cardiovascular disease or diabetes.

Egg intake should be controlled in hyper-responders to dietary cholesterol (perhaps at least 15% of the population), as an increase in egg consumption in these people will affect them to a greater extent than others. But it’s not easy to figure out how your genetics impact the way you respond to dietary cholesterol. 

Overall, you need to zoom out and look at egg intake in the context of your overall diet. Remember, nobody eats one food in isolation. If the foundation of your diet is healthy and full of nutrient-dense foods, there is very likely more wiggle room for eggs without impacting cholesterol numbers and disease risk. Are a few eggs a week in the context of a whole food–based diet going to trim years off your life? Likely not, and that’s a theory that definitely warrants more research dollars.

Very few studies involve healthy people eating very good diets overall. With that said, a study in the Journal of Nutrition found that including two eggs a day in the context of a plant-predominant diet did not negatively impact heart disease risk factors. The nutrients that eggs provide might help round out a plant-based diet nicely.

But if you’re adding the cholesterol from eggs to a typical Western diet full of other foods high in cholesterol and saturated fat, that could be more problematic. If you’re eating bacon or sausage and eggs or dumping a bunch of cheese on your scramble, then the cholesterol from eggs may worsen the effects that the saturated fat in these other foods has on your cholesterol levels. And it never makes much sense to replace the calories from eggs with calories from sugary boxed cereals, processed breakfast meats, pastries, and pancakes drowning in syrup. 

The bottom line is that the right amount of eggs might be heavily dependent on the rest of your diet, with genetics and more playing a supporting role. So get cracking if you want, but just go easy on the side of greasy bacon.