According to marketing materials and celebrity testimonials, collagen is a one-stop solution for aging skin, hair, nails, bones, joints, and more. And plenty of consumers have bought in. People spent $2 billion on collagen supplements in 2021; a total that is projected to keep growing. For collagen, however, the hype is a step ahead of the science, experts say.

Although some studies suggest there may be some potential benefits, especially for the appearance of skin, nothing is clear cut. Also, it’s possible to make diet and lifestyle choices that accomplish the same goals. For now, says board-certified dermatologist Sonya Kenkare, there is not enough evidence to convince her to recommend collagen supplements to her patients or to take them herself.

After she had a baby a couple of months ago, her hairstylist recommended collagen to prevent her hair from falling out. “I haven’t done it because there isn’t a lot of evidence,” says Kenkare, of Rush University in Chicago. “I’ve seen a lot of people take it, and I often tell them that we have no data to support that it’s actually doing something.”

What is collagen?

Collagen is the most abundant protein in mammals, making up 30 percent of the proteins in our bodies. It is a key structural element of skin, ligaments, muscles, tendons, bones, blood vessels, the intestinal lining, and other connective tissues, says Julia Zumpano, a registered dietitian at Cleveland Clinic’s Center for Human Nutrition.

Shaped like a triple helix with three chains of amino acids twisted together tightly enough to make the protein strong and rigid, collagen has been categorized into 28 types, based on molecular structure and where it is found in the body. Ninety percent of the body’s collagen is Type I, which is found in skin, bones, tendons, and ligaments, according to the Cleveland Clinic. Types I through V are more common than the rest.

Where does collagen come from and what does it do?

Our bodies make collagen, a job done primarily by specialized cells called fibroblasts. To string together amino acids into collagen, these cells also need nutrients such as vitamin C and zinc, Zumpano says.

Collagen’s main job is to provide support, strength, and structure, giving elasticity to the skin and protecting organs. It also helps blood clot and new skin cells grow.

When the body can’t make sufficient collagen, these processes break down. In people with the genetic disorder Ehlers-Danlos syndrome, for example, symptoms can include soft and stretchy skin, excessive bruising, and unstable joints. Autoimmune conditions such as lupus and rheumatoid arthritis can also damage collagen.

What happens to collagen as you age?

With age, our bodies produce less collagen, which also gets broken down more quickly. As collagen levels decline in the dermis, an inner skin layer, skin sags and becomes wrinkled. A variety of factors can accelerate that process. Studies show that over time, smoking, alcohol, UV light, and high sugar consumption all lower collagen production and make the protein weaker, leading to more wrinkled skin.

What are collagen supplements?

The market is full of collagen products, but there are no standards for what’s in them. As a dietary supplement, collagen is not regulated by the U.S. Food and Drug Administration, and companies are not required to demonstrate their safety, effectiveness, or purity.

Products may advertise collagen derived from beef (bovine), fish (marine), chicken, or other sources. They may specify the form, such as Type I or III. Some labels use the words “collagen peptides,” which are short chains of amino acids that combine to make the longer collagen proteins. Supplements may be in the form of pills, powders, gummies, or drinks.

It is safe to take between 2.5 and 15 grams of collagen peptides daily, Zumpano says. But ultimately, the body can’t absorb whole collagen, and will instead break the protein down into its component amino acids, which then get used by the body as needed.

What is the evidence that these supplements work?

Collagen is a primary ingredient in many of the filler injections used in cosmetic procedures, which can plump up the skin temporarily before getting broken down by the body, Kenkare says. But as an oral supplement, data linking collagen to noticeable skin changes is not overwhelming.

Some studies suggest that collagen supplements might lead to modest improvements in the integrity of your skin, Zumpano says. But all come with caveats. In one 2021 review of 19 studies that included 1,125 people, mostly women, researchers from Brazil found evidence of reduced wrinkles and improved skin elasticity and hydration in people who took collagen supplements.

All the supplements, however, included other ingredients that may have contributed to those results, according to an analysis by dermatologists at Harvard Medical School and Massachusetts General Hospital. Randomized controlled trials that look at effects on skin elasticity, hydration, wrinkles, or other measures tend to be small, they added. Studies of hair and nails are practically nonexistent. “More research is needed,” Zumpano says.

Beyond skin, some studies have linked collagen supplements with improvements in joint mobility and knee and joint pain for athletes and people with osteoarthritis. Research is ongoing to tease apart the details.

There are other ways to reap the potential benefits of collagen without supplements, experts say. Plenty of foods contain collagen, including meat, chicken, fish, eggs, and bone broth. Zumpano also recommends consuming vitamin C, copper, zinc, and the amino acids proline and glycine to supplement collagen production. Retinoids, ingredients in many anti-aging skin creams, work by increasing collagen production, Kenkare adds.

Zumpano suggests eating collagen rich foods and the nutrients for the body to build its own collagen because “we can’t say that the supplement is a cure all.”