What is Keratin? Here's What a Dietitian Has to Say About It

Getty Images / Holger Scheibe

You're might be familiar with collagen and elastin, even if that means you're just semi-aware of the benefits of collagen. Well, keratin is another protein just like collagen and elastin. It's also a critical structural component in your hair, skin, and nails. And like collagen and elastin, our bodies make less keratin as we get older. (Can you hear me groaning?)

Related: 10 Best Foods to Eat for a Collagen Boost

So, what is keratin? Keratin isn't just one protein—it's a mixture of different amino acids. And there are various types of keratin (mm-hmm, just like collagen again). You'll find keratin in—and it's extracted from—animal horns, hooves, wool, and feathers. From there, it's typically turned into supplements you can eat, or added to hair products like shampoos and serums.

What Happens When We Don't Have Enough Keratin?

Your body makes the keratin it needs from protein in your diet. Plus, vitamins like biotin and vitamin A play a role in keratin production, too.

If your body isn't able to make enough keratin (either because your diet is falling short in protein, key nutrients, or something else is going on), the effects will likely be noticeable in your hair, nails, and skin. Your hair and nails may grow at a slower rate, and become more brittle and less shiny and smooth. Another side effect is thinning hair. Your skin may appear more dull, drier, and even older-looking.

How to Boost Keratin Levels

Because keratin is a building block of hair, skin, and nails, it's a natural segue to associate keratin with strengthening hair and nails, and supporting more youthful-looking skin. But before you lean into supplements, look at your diet. Eating a healthy diet that's ample in protein and keratin-making nutrients like biotin and vitamin A is key to encouraging keratin production and replenishing your keratin levels.

Don't turn to keratin supplements as your first line of defense: while a small handful of studies suggest keratin supplements may help with hair, nails, skin, and more, the research is too preliminary. More research is needed to support these findings and supplement effectiveness.

Health Benefits of Keratin

That said, the potential benefits to supplementing with keratin show promise. Here's what some of the research shows:

Stronger, smoother nails

One study found that adults who took a branded soluble keratin supplement for three months strengthened and improved the appearance of their nails. More specifically, half of the keratin supplement group had no broken nails at the start of the study. By the end of the study, 87 percent had no broken nails whereas only 57 percent of the placebo group had no broken nails. The results for smooth nails were fairly similar with the supplement group improving significantly.

Healthier-looking hair

In the same study as the nails, researchers also assessed participants hair and found that those who took the keratin supplements lost less hair, and their hair got stronger and brighter-looking compared to their counterparts who got a sugar-based placebo.

Another slightly older study looked at a hydrolyzed keratin-infused shampoo and conditioner and found that it brightened and softened hair more than a basic shampoo and conditioner. Researchers concluded that the keratin-filled products hydrated hair and sealed hair cuticles.

How to Supplement with Keratin

Based on the available research, supplementing with keratin doesn't seem to lead to many, if any, adverse effects, so if you'd like to try it, go for it. That said, most supplements are totally unregulated, so be sure to look for a third-party certification (like USP or NSF) that test for ingredient accuracy.

Keratin can be quite difficult to digest—even the acid in your stomach can't break it down. Remember it's found in animal hooves, feathers, and wool. You'll want to look for soluble keratin (aka hydrolyzed keratin), which is the form that your body can digest. You may also want to consider pairing your keratin supplement with some biotin to support keratin production.