Egg proteins as drugs: Beneath the shell

Eggs are a nutrient-dense, delicious addition to a diverse diet. They’re rich in protein and offer a smorgasbord of micronutrients.

These are “essential” because your body can’t make them, so you need to get them from your diet.

But today, we’re not covering the health benefits of eating eggs.

Instead, we’re looking at how scientists are investigating egg proteins as potential new treatments for some common health conditions.

Although much of the research is still in an experimental phase, it’s fascinating stuff.

A quick note on proteins

The words “protein” and “peptide” will come up a lot today, so it’s worth having a quick recap.

They’re both built from chains of amino acids. Proteins are long, often folded chains, and peptides are short chains. 

Proteins and peptides carry out a wide range of jobs in your body. Their properties vary depending on factors such as which amino acids are in the chain, their order, and how the chain is folded.

The 3D structure of proteins defines their function. So, if they’re unfolded, for instance, when exposed to heat during cooking or acid in the stomach, they lose that function.

 Proteins are also important building blocks. They build the structures in your body, including your organs and muscles.

Why egg proteins?

Eggs are relatively cheap, widely available, and contain a wonderful variety of proteins.

Scientists have identified 550 distinct proteins in eggs but, so far, they've only characterized around 20. 

And, as researchers dig into these little-known peptides and proteins, they’re unearthing some potentially valuable properties.

Below, we’ll cover research into how some egg proteins appear to have antimicrobial, anticancer, anti-inflammatory, and blood pressure-lowering effects. 

Instead, we're looking at research that has examined single proteins extracted from eggs.

In isolation, these proteins might be useful, whether for the food industry or medicine.

Antimicrobial powers

Antibiotics have saved countless lives. However, their overuse has produced a worrying rise in antibiotic resistance. 

According to the World Health Organization (WHO), this is “one of the biggest threats to global health, food security, and development today.”

Interestingly, they fend off microbes in a variety of ways. Here are some examples:

Lysozyme: This protein breaks down the walls of some bacteria. Manufacturers already use it as a food preservative and in some drugs. 

Ovotransferrin: This protein binds to iron, making the element unavailable for bacteria. It keeps them from growing.

Avidin: This binds to biotin (vitamin B7), which some bacteria need to thrive.

Ovoinhibitor: This blocks enzymes that bacteria need to function.

Because the structures of proteins dictate how they work, many of their antimicrobial powers are lost during digestion.

But even when some egg proteins are broken into smaller peptides, they still have antimicrobial properties. 

For instance, studies have shown that when gut enzymes cut lysozyme into short peptides, they can still kill bacteria.

This protein is easy to purify from egg whites and is a natural food preservative.

Scientists continue to study lysozyme's properties to understand how to maximize its applications in the food industry.

Overall, as researchers learn to harness the powers of the proteins in the list above, other uses in industry and medicine might surface. 

Eggs vs. cancer

For decades, scientists have investigated whether some egg proteins might help combat cancer.

For instance, ovomucin is an egg glycoprotein — a protein attached to a carbohydrate. In the 1990s, scientists found that when they injected adapted ovomucin into tumors in mice, it slowed their growth.

In laboratory studies, scientists have shown that sections of the egg protein ovotransferrin can kill human cancer cells.

To reiterate, cooking and digestion break down these proteins, so any potential anticancer effect is lost.

The existing research only shows that extracted egg proteins hinder cancer when applied directly to cancerous cells grown in a lab.

There’s been relatively little research into the anticancer properties of egg proteins in the last few years. The evidence is still limited in animals and nonexistent in humans.

Anti-inflammatory?

Inflammation is a healthy response to an injury or infection. But if it persists once the threat has passed, over time, it can damage cells and tissues.

For instance, a lab study using peptides derived from ovotransferrin showed an anti-inflammatory effect on cultivated cells. The authors suggested that these compounds might help reduce inflammation in the gut.

In an earlier study, scientists used a pig model of colitis, which is an inflamed gut. They found that egg lysozyme supplements reduced inflammation.

Another lab study looked at a group of egg yolk proteins called livetins. The researchers found that these proteins reduced an inflammatory reaction in a type of white blood cell. 

Lowering blood pressure

High blood pressure, or hypertension, affects more than 1 billion people worldwide. And some scientists are asking whether egg proteins could lend a hand.

Many current hypertension treatments work by inhibiting angiotensin converting enzyme (ACE). 

This enzyme helps produce a compound that constricts blood vessels, thereby increasing blood pressure. If ACE is inhibited, it can’t produce this compound, so blood vessels relax, and blood pressure drops.

Some evidence suggests that certain proteins extracted from eggs might also inhibit ACE. 

In fact, one study found that some egg proteins could inhibit ACE more effectively than a common blood pressure drug — in the laboratory.

Scientists have shown that even short fragments of ovotransferrin appear to block ACE in the lab.

Importantly, they haven’t tested these egg products in humans. Most of the research so far has been in the laboratory.

However, there has been some animal research on peptides derived from ovotransferrin. 

For instance, one study involved rats susceptible to hypertension. The researchers found that these peptides, when given orally, lowered the rats’ blood pressure.

Again, there’s more work to be done. But finding a new way to address such a common health issue could improve the lives of millions.

A bright future?

We already have drugs that can help treat all the health conditions we’ve covered today, but many of these drugs come with significant side effects.

The authors of a review of research on ovotransferrin offer hope that naturally occurring proteins might “bypass the adverse secondary effects associated with synthetic pharmaceutical agents.”

Aside from the conditions mentioned above, researchers are also investigating whether egg components might help heal wounds quicker, protect eye health, and slow aging.

Eggs have a bright future for sure.