Olivia Munn Swears This Food Is The Secret To Her Glowing Skin

Earlier this year, actress and startup maven (in true #ladyboss style, she was one of the original investors in Uber and Wag) Olivia Munn made waves when she revealed her Japanese skin care secret—sweet potatoes. "I get my potatoes from a Japanese market. I’ll take one sweet potato, slice it into one-inch-thick slices, and then dust it with olive oil and cinnamon, put it in the oven, and do that as dessert. I'll eat those as often as I can—a couple every day," she told the Cut.

This week, on late-night show Busy Tonight, she further expanded on her sweet potato love. "I did some research, and there's a town in Japan called the City of Long Life, and these people are 80 or 90 years old and have no wrinkles. They live in a remote part of Japan where they grow these potatoes, that, when you cut them open, are all slimy inside," she told host Busy Philipps. "That slime is hyaluronic acid."

Munn says eating high-hyaluronic-acid foods twice a day transformed her skin—and it turns out, her root vegetable remedy is actually validated by science. "While it definitely won't make you look 'young forever,' ingesting hyaluronic acid does increase the moisture content of the skin1, resulting in a plumper, more hydrated appearance," explains Sarah Villafranco, M.D., a skin care expert and founder of Osmia Organics. "As we age, we have trouble retaining moisture in the skin due to structural changes, sun damage, and decreased hyaluronan in the skin layers. Consuming hyaluronic acid, either in food or supplement forms, will result in more hyaluronic acid in the skin itself, making skin feel softer, appear smoother, and be able to retain moisture more effectively."

While she notes that most of the studies have been done in Japan, so it's possible that results could vary based on race and geographic location or climate, most functional practitioners agree that it's likely safe, especially when ingested in whole food forms. If you can't get your hands on Munn's special sweet potatoes ("the websites that I would buy them from stopped selling them because too many people went there!" Munn complained to Philipps), there's one source of hyaluronic acid that functional practitioners rave about—bone broth.

"I'm a firm advocate that healthy skin has to start from the inside out," explains Will Cole, D.C., a functional medicine practitioner and mbg Collective member. "One of the reasons people love bone broth so much is because it is one of the richest food sources of hyaluronic acid, in addition to collagen, another food that's great for skin," he says, noting that the modern Western diet tends to be low in these two nutrients.

Hyaluronic acid has other benefits too, including relieving joint pain and inflammation2. The verdict? If you want to try it, go for it, either in supplemental or whole food form. "It's a pretty safe supplement to try, and you could see results within two to four weeks," says Villafranco. "If you're vegan, make sure you're getting a vegan supplement, as most HA supplements are made from chicken and rooster combs. The studies show1 that results are the same for vegan hyaluronic acid."