Collagen is a protein found abundantly in your body as it plays a major role in your connective tissues.

It helps with structural support and elasticity and is a factor in how young your skin, hair, and nails look.

Collagen has also been linked to relieving joint pain, improving muscle mass, and preventing bone loss.

Collagen starts to decrease in your 20s, and by your 40s, lower collagen levels can start to cause wrinkles, sagging skin, and thinner, graying hair (1).

Hair and nails mostly consist of a protein called keratin.

Keratin is made up of several amino acids, which are the building blocks of all proteins.

Proline is a major amino acid of keratin. Collagen is mostly made up of three amino acids: proline, glycine, and hydroxyproline.

When you eat proteins, including collagen, your body breaks them down into amino acids.

Your body then uses these amino acids to build new proteins in the body.

So, taking a collagen supplement will provide your body with plenty of protein, especially the amino acid proline, that your body can use to create keratin for your hair and nails.

While thinning hair and hair loss are associated with aging, no one really knows why.

Your body produces less collagen as you age, which may be one factor contributing to hair thinning and loss.

Here are some theories about how collagen helps produce healthy hair.

Having brittle nails is a common problem in which the nails have a rough surface, are ragged, and peel.

If you have brittle nails, you might feel that your nails are soft, dry, weak, easily broken, and won’t grow long.

About 20% of the population have brittle nails, and women are affected twice as often as men (12).

Nails can become damaged or unhealthy for many reasons.

Iron deficiency, hypothyroidism, acrylic and gel nails, working with your hands, or frequent hand washing can all cause nails to become weak, brittle, or easily broken.

One study investigated whether taking hydrolyzed collagen every day would improve the symptoms of brittle nails and make the nails grow faster (13).

The participants took 2.5 grams of collagen each day for 24 weeks and then stopped the treatment for four weeks.

The researchers found that the hydrolyzed collagen supplement increased the growth rate of the nails by 12% and decreased the number of broken nails by 42%.

64% of the participants had an improvement in their brittle nails, and 88% had improvement four weeks after the collagen supplement was stopped.

80% of the participants said the collagen supplement made their nails look better and were completely satisfied with the treatment. 75% thought their nails were stronger, and 71% felt their nails were growing faster and longer.

Any benefit of a collagen supplement depends on how well it is digested and absorbed in your gut.

Collagen supplements are sometimes hydrolyzed to make collagen protein chains that are easier for the body to absorb.

Hydrolyzed means that the collagen is already broken down into smaller pieces of proteins. So, it is more bioavailable and better absorbed by your body.

Look for hydrolyzed collagen powder that is unflavored so you can easily add it to your favorite hot or cold drinks, smoothies, oatmeal, yogurt, or any soft foods.

Avoid collagen supplements that have added artificial sweeteners or flavorings.

A typical dose of hydrolyzed collagen is around 10 g per day.

While collagen is generally safe, you should always talk to your doctor before taking any supplement.