She puts on the latest serums, has skin-rejuvenating laser treatments, never leaves the house without sunscreen, and — for the past 6 months or so — spikes her morning smoothie each day with a hefty scoop of powdered cow, chicken, and fish collagen.

“Honestly, it doesn’t taste like anything,” she says, adding that her plump skin, stronger nails, and pain-free joints make her unusual breakfast choice worth it. “I’ve really started to notice a difference.”

For centuries, Chinese women have viewed collagen as a Fountain of Youth, routinely consuming foods like donkey skin in hopes of smoothing withered skin and preserving aging joints. In the United States, collagen became best known in the 1980s as an expensive injectable filler to plump lips and soften lines. But only in recent years, as companies have come up with more appetizing ways to take it (including fruity chews, vanilla-flavored-powders and easy-to-swallow capsules) has edible collagen begun to catch on here.

In 2018, thanks in part to a small but growing body of evidence suggesting it can improve skin, ease arthritis symptoms, promote wound healing, and fend off muscle wasting, U.S. consumers are expected to spend $122 million on collagen products. That’s up 30% from last year, according to market research firm Nutrition Business Journal.

But as it’s gotten more popular, there have been questions about how well it works and concerns about its safety.

“It’s definitely among the top three products people ask me about,” says Mark Moyad, MD, director of the complementary and alternative medicine program at the University of Michigan Medical Center. “It’s also one of the most wacky and controversial.”

The Body’s Scaffolding

Collagen — a protein that binds tissues — is often called the body’s scaffolding.

“It’s the glue that holds the body together,” says New York dermatologist Whitney Bowe, author of The Beauty of Dirty Skin: The Surprising Science of Looking and Feeling Radiant from the Inside Out.

“As we get older, we break it down faster than we can replace it,” she says.

Injecting collagen has fallen out of favor in many medical skin care practices, since it doesn’t last as long as other fillers and tends to prompt allergic reactions. And when it’s put on the skin, it doesn’t absorb well and doesn’t work often, Bowe says.

When she learned a few years ago that people were eating it instead to make their skin look more youthful, she was skeptical. But she has since changed her mind.

“Just in the last few years, there have been some impressive studies showing that ingestible collagen can indeed impact the appearance of skin,” says Bowe.

One 2014 study of 69 women ages 35 to 55 found that those who took 2.5 or 5 grams of collagen daily for 8 weeks showed a lot of improvement in skin elasticity, compared with those who didn’t take it.

Another found that women who took 1 gram per day of a chicken-derived collagen supplement for 12 weeks had 76% less dryness, 12% fewer visible wrinkles, better blood flow in the skin, and a 6% higher collagen content.

But Moyad, author of The Supplement Handbook: A Trusted Expert’s Guide to What Works and What’s Worthless for More Than 100 Conditions, says many of the studies done so far on collagen are small and at least partially funded by industry.

“The science is truly in its infancy,” he says. “There’s a lot of conflict of interest, and not enough quality control.”

But he, too, believes it may hold promise.

Other dermatologists question how well it will work.

Augusta, GA-based dermatologist Lauren Eckert Ploch says stomach acids break down collagen proteins you eat before they reach the skin intact. “It is unlikely that someone would see any benefit from it.”

One recent study of 53 elderly men with sarcopenia, a loss of muscle caused by aging, found that those who took 15 grams of collagen daily, in addition to lifting weights three times per week for 3 months, gained significantly more muscle and lost more fat than those who only lifted weights.

Another study of 89 long-term care residents with pressure ulcers found that those who took collagen supplements three times daily for 8 weeks saw their wounds heal twice as fast.

And, while research is mixed, a few studies have shown collagen supplements to help with arthritis pain and sports-related joint pain.

Skepticism Remains

All that said, doctors have their concerns.

“I think the elephant in the room here is safety,” says Moyad. “We are talking about ground-up fish, chicken, pig, and cow parts, and these parts tend to act as sponges for contaminants and heavy metals.”

While little evidence exists yet to suggest that collagen supplements could lead to heavy metal contamination, several collagen supplement companies — aware of these concerns — have begun to advertise how they test for heavy metals and keep them to a minimum.

“At the time of manufacture, heavy metal testing is done and the product is approved for human consumption once it passes all testing,” says a page on the Great Lakes Gelatin site. The company says its limits for arsenic are below the standards set by government agencies.

Meanwhile, dermatologists and consumer groups have also said they were concerned that those ground-up hooves, hides, and nerve tissues — particularly if they come from cows — could carry diseases like bovine spongiform encephalopathy (BSE), or mad cow disease.

In 2016, the FDA prohibited the use of some cow parts in dietary supplements to “address the potential risk” of the presence of BSE. (Human consumption of BSE-infected meat has been linked to neurological disorders.) The FDA exempted gelatin — a key collagen source — from the ban, “as long as it is manufactured using specified industry practices.”

“It is not a fly-by-night ingredient that showed up out of nowhere,” he says. “It has good science behind it, and the companies in this space are reputable and have been around for a long time.”

He says he has seen no evidence that heavy metals are more of a problem in collagen supplements than other supplements but adds that both government and industry require companies to keep levels of such contaminants below a certain threshold. Some collagen companies, aware of the concerns, even advertise their heavy metal testing practices.

While collagen makers tend to use “low-risk” animal materials in their products anyway, the BSE issue is definitely on their radar screen too, he says, with all reputable companies asking suppliers to certify that their product is BSE-free.

But Valori Treloar, a Massachusetts dermatologist and nutritionist, says dietary supplements are not regulated as rigorously as drugs.

“I think collagen is interesting and there is some data out there suggesting benefit, but I prefer for my patients to eat food,” she said, noting that a homemade stock using bones from chicken, fish, or beef can be a good source of the protein.

How to Choose

If you are interested in trying collagen, doctors agree that it’s important to choose wisely.

Look for companies that get their bones and tissues from cage-free, free-range, and antibiotic-free sources.

“It might help, and it probably won’t harm, unless you are not being diligent about quality control,” says Moyad.

Look for a trusted brand with a third-party label, like NSF or USP.

And steer clear of fancy mixtures that combine collagen with probiotics, fiber, or other additives, which could interact with the collagen and change how well it works.

Mora says she did that, and she’s convinced it has helped her.

“My goal is not to look like I am 20, but rather to look good for my age,” she says.

At 60, she believes her skin care routine is working.