Egg Yolk Has Been Used on Hair for Centuries—But Does it Actually Do Anything?

What makes a truth? How much proof or evidence do we need to accept something as absolute? How many peer-reviewed scientific reports turn a theory into a fact? It's a difficult question, especially when it comes to the world of DIY beauty.

Centuries of tradition and practice have cemented the power of natural ingredients and at-home beauty recipes—and there's definitely scientific evidence to back up a lot of these claims. When it comes to hair, coconut oil, honey, bananas, and avocados are all lauded for their reparative and moisturizing properties, with ample scientific backing. But when it comes to egg yolks, an ingredient that has been used in hair treatments since as early as the 11th century, the jury still seems to be out.

That's why we phoned a few (very smart, very qualified) friends: trichologist Mandy B, hairstylist Jamie Wiley, cosmetologist Whitney White, and board-certified dermatologist Hadley King, MD.

So what's the final verdict? What eggs-actly is the deal here? Cheap puns aside, read on for what the experts have to say about the benefits of egg yolks for hair (and the legitimacy of those claims).

Potential Benefits of Egg Yolks for Hair

While there isn't a ton of scientific research supporting the benefits of egg yolks for hair, the ingredient has been used in DIY hair treatments for thousands of years. That being said, there is ample evidence that some substances found within egg yolks (proteins, fats, vitamins, cholesterol, etc.) are beneficial to hair. So keep in mind that the benefits listed below are not necessarily facts as much as very strong theories.

• Helps moisturize and nourish hair: The protein and fats in egg yolks can help nourish hair, promote shine, and enhance softness.
• Repairs damaged hair and protect hair from further damage: The cholesterol found within egg yolks is filled with lipids that can help repair hair damage caused by color, chemical, heat, and excessive manipulation. The combination of folate, biotin, and vitamins A and E can help prevent further breakage and damage, says Wiley.
• Stimulates hair growth: "There are some who believe egg yolks could stimulate hair growth, but there's not much evidence here," says King. "Some researchers in Japan found a peptide that is found in egg yolks to stimulate hair growth in mice, but we would definitely need more data to prove this."

As we (and King) said before, there is limited scientific evidence to back up these claims. In fact, trichologist Mandy B says she'd avoid egg yolks in hair altogether. While egg yolks have a pH level of around 6.5 to 6.7, the hair has a general pH level of around 4.5 to 5.5, she explains. And, according to Mandy B, raising the pH level of the hair could potentially cause breakage, frizz, and dryness (for reference, most deep conditioners are around 3.5 on the pH scale).

That being said, limited scientific evidence is not the same as no scientific evidence. And while Mandy B's explanation makes perfect sense in theory, it's also important to pay attention to the research that does exist. And that research does seem to confirm the benefits of egg yolks for dry, damaged hair. According to Wiley, one area of this research focuses on a specific fat within eggs called lecithin.

Lecithin, which is a generic term to describe any group of yellow-brownish, naturally occurring fatty substances, is not only found in eggs but also in a slew of hair conditioners and similar hair products thanks to its emollient properties. It's also water-binding and stabilizing and features emulsifying properties.

And lecithin is just one of many substances found within egg yolks that have been definitively linked to helping hair. Another study suggests that the protein and fats found in egg yolks help nourish and strengthen hair. Meanwhile, yet another study focuses on the benefits of cholesterol for hair (which egg yolks are chock-full of).

So while the scientific community seems to be at odds when it comes to whether or not egg yolks definitively benefit hair, there's ample evidence on the side of supporters.

Hair Types Considerations

Here's the good news: Whether or not egg yolks actually benefit the hair, the treatment is fairly low risk (not to mention low-cost and simple). While it's generally okay for all hair types, those sensitive to protein or egg products should proceed with caution. White suggests patch-testing a small section of the hair in the back to see how it responds prior to covering the entire head.

How to Use Egg Yolks for Hair

If you're interested in testing egg yolks out on your own hair, a DIY recipe is your best route—there aren't any egg-based hair masks out on the market (at least that we know of). "Beat 2-3 eggs until frothy and then apply to the hair," King recommends. "Cover with a shower cap for 20 minutes. Rinse with cool water. Then shampoo and condition as usual."

Wiley suggests applying a simple DIY mask once or twice a month to keep hair strong and soft. Follow her recipe below.

Ingredients:

• 2 egg yolks
• 1 tablespoon unflavored mayonnaise

Directions:

1. Combine ingredients and whip together in a bowl.
2. Apply the mixture from roots to ends and cover with a shower cap.
3. After 20 minutes, rinse the hair thoroughly.
4. Using cold water, follow with shampoo and conditioner.

White suggests mixing egg yolks with a carrier oil (like olive or avocado oil) for easier distribution and an extra boost of fatty acids. She also suggests leaving on the mask for no more than 30 minutes, after which it might begin to harden on the hair.