This protein source has the highest protein digestibility-corrected amino acid score, but it’s got plenty of other superpowers, too.
Hey, do you remember John Coffey from “The Green Mile”? (“I’m tired, boss…”) It’s a stretch, but I see a similarity between Coffey and chicken eggs. No, really. To begin with, both were wrongly accused of horrible crimes.
In the case of Coffey, he was convicted of murdering a couple of young sisters. In the case of eggs, they were convicted of causing high cholesterol and heart disease, leading to – or playing a role in – the death of millions.
Coffey was never exonerated. He got fried. (Hey! Another similarity!) Eggs, however, were acquitted. In 2015, the United States Department of Agriculture (USDA) Dietary Guidelines did away with the upper limit for dietary cholesterol, emphasizing that egg consumption no longer needed to be restricted.
Furthermore, several large studies have indicated that eggs don’t increase the biomarkers associated with heart disease, but even the studies that still do are suspect.
Oh yeah, one more similarity between John Coffey and eggs: Both had/have a supernatural, or almost supernatural, power to heal.
Researchers Michael Puglisi and Maria Luz Fernandez compiled just a few of the attributes of eggs in the journal “Nutrients.” I’ve included some of the most important attributes below, with some additional info from my personal egg data bank/data refrigerator.
Eggs and Skeletal Muscle Health
The protein digestibility-corrected amino acid score, or PDCAAS, is the gold standard when it comes to measuring protein quality. The score is a combination of a particular protein’s digestibility and how well it fulfills amino acid requirements.
So anything over 90% is considered pretty damn good. Meat and fish come in at a hefty 92-94%. Eggs, however, clock in at a surreal 118%.
How do you get a PDCAAS over a hundred? Well, not only is egg protein digested at a 97% rate, it also contains an amino acid complement that, in many cases, exceeds human requirements. Hence the mathematically puzzling number.
Still, most of the people who work with PDCAAS don’t accept any number over 100%, so they just round down. Let’s just say eggs have a perfect protein score.
Multiple studies also show their anabolic strength. When Matsuoka, et al., fed male rats a diet consisting of 20% egg white protein or casein, the egg-protein rats were found to have a greater average carcass mass and greater gastrocnemius weight than the rats that were fed conventional (not micellar) casein. They attributed this difference between egg white and plain casein to greater net protein utilization (95% compared to 70% for casein) from egg white, in addition to the higher digestibility of the eggs.
Of course, eating whole eggs is even more anabolic than eating egg whites. Van Vliet, et al. (2017) fed young weight-trained men whole eggs or egg whites (18 grams of protein) and found that the whole eggs spurred a greater surge in mTOR, which is probably the most important cell-signaling complex for muscle growth. The higher the levels of mTOR, the greater the synthesis of protein.
Most importantly, that same van Vliet study found that eating whole eggs increased post-exercise muscle protein synthesis about 45% more than plain egg whites.
This apparent superiority of whole eggs in promoting protein synthesis probably has to do with the assorted micronutrients, phospholipids, and microRNAs contained in the yolk.
The scientific literature is filled with similar studies, too.
Eggs and Weight Loss
High-protein foods, in general, have a high satiety index (SI), but eggs also have the unusual property of suppressing plasma ghrelin levels (ghrelin is a hormone associated with appetite stimulation): the less ghrelin swimming through the blood, the less you want to binge on Reese’s Pieces.
Eggs are also thought to reduce lipid absorption, in addition to inhibiting lipase activity, both of which would logically contribute to a reduction in abdominal fat.
One study of 25 men compared the SI effects of eating iso-caloric breakfasts consisting of either eggs or bagels (Missimer et al, 2017). Okay, that’s not much of a contest – the eggs were more filling than the bagels. But what was surprising is that guys who had the egg breakfast consumed fewer calories over the next 24 hours, meaning that the effect of eggs on appetite suppression is no rapidly fleeting thing.
Another study that compared eating eggs to bagels (what’s with all the bagel studies?) for breakfast found that the egg group had a 65% greater reduction in waist circumference and a 10% greater reduction in body fat. Again, not much of a surprise, but no differences were found in the cholesterol levels of the two groups, despite the egg group ingesting an extra 400 mg. of the stuff every day (Rueda, et al, 2013).
Eggs and Sarcopenia
Sarcopenia is the age-related decline of skeletal muscle mass and strength. The resultant loss of function can increase the risk of type 2 diabetes, cardiovascular disease, Alzheimer’s and other forms of dementia, and even some cancers.
Then there’s the peculiar malady known as “sarcopenic obesity,” characterized by a big-time loss of muscle mass and concurrent rise in fat mass. This is why many old people look like Mr. Potato Heads pushing a walker.
While just eating virtually any kind of protein would help the elderly population, eggs seem particularly suited to the job. The thing is, it’s difficult for a lot of older people to get the requisite 28 grams of protein they usually need by eating big, unappetizing, intimidating hunks of meat.
They might also have difficulties chewing or swallowing and have pre-existing malnutrition or chronic diseases. Cutting into a T-bone or tackling a quarter-pound burger might seem daunting. Not only that, but they often don’t feel like eating because of poor appetite or low caloric needs in general.
Eggs, however, are incredibly easy to digest and can be eaten at any time, in addition to being inexpensive. It seems the only hurdle would be to convince old folks – who lived in the dark times when eggs were anathema to heart health – that eggs are no longer the cholesterol menace they were thought to be.
Eggs, Immunity, and Protection Against Chronic Disease
Simply by enhancing skeletal muscle health, eggs can improve insulin sensitivity, reduce risk of prehypertension and hypertension, ward off cardiovascular disease and osteoporosis, and, in general, reduce overall risk of all-cause mortality.
On a molecular basis, chicken eggs are teeming with immunoglobulin Y (IgY), which is the avian equivalent of the mammalian immunoglobulin G. It’s thought to protect the developing chicken embryo in the same way IgG protects human fetuses. Okay, so how’s that going to help my Uncle Wilbur with the grippe? Well, IgY has been used to promote passive immunity to treat and prevent human and animal diseases caused by hostile microbes.
Egg proteins also contain the enzymes lysosome, avidin, phosvitin, and ovotransferrin, each of which put the whup on various bacterial life processes.
They even offer protection against inflammatory bowel disease and seem to suppress tumors of the colon (egg yolk proteins, specifically).
Okay, Yeah, But How Many Eggs Can I Safely Eat?
The evidence is overwhelming that whole eggs are nutritionally superior entities, but regardless, most of you probably can’t get that cholesterol rap out of your head. Do you treat eggs like they’re something you dare expose yourself to only occasionally, like the midday sun, dental X-rays, or Adele songs? Or do we throw caution to the wind and eat eggs ad libitum?
It’s hard to say definitively because there aren’t any studies that I know of that involved eating a henhouse’s worth of eggs every day.
Still, we can use a little logic to help us make the decision. First, eggs have been “exonerated” by several studies. Secondly, dietary cholesterol has very little impact on blood levels of cholesterol. Your liver and intestines manufacture about 80 to 85% of what you need to make cell membranes and to produce hormones, vitamin D, bile acid, etc.
The rest, however, comes from your diet. Your body will regulate levels to some extent, so if you don’t eat enough cholesterol, the body produces more. Conversely, it produces less when we eat a lot.
But far more causative of unhealthy cholesterol levels than dietary cholesterol is an unhealthy diet in general: lots of processed carbs, a lack of physical activity, and excess weight.
Saturated fats are said to raise cholesterol, too, but that mostly happens when it’s eaten in conjunction with cholesterol. And yes, eggs contain both sat fat and cholesterol, but the amount of saturated fat in an egg (about 1.6 grams) is a pittance when compared to the average steak (around 21 grams).
So, eff it, I say. Eat your damn eggs. Their nutritional qualities can’t be ignored, and they shouldn’t be dismissed from your diet. They, like all exonerated criminals, deserve their rightful place in society.
- Puglisi MJ et al. The Health Benefits of Egg Protein. Nutrients. 2022;14: 2904.
- van Vliet S et al. Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men. Am J Clin Nutr. 2017 Dec;106(6):1401-1412. PubMed.