Margot Robbie Drank Special Tea to Get Perfect Skin for 'Barbie' Movie

It wasn't just makeup and facials that helped the "Barbie" cast achieve doll-perfect skin.

Jasmina Vico, a skin-health specialist, was in charge of keeping the stars glowing on-screen, and she believed the key was more than skin-deep.

"Everything in the movies is about lighting," Vico, a facialist who is based in London, told Vogue. "That's when I thought, OK, we're going to work on the liver, calm the nervous system, and make skin glow. But, crucially, we're going to work on that glow from within."

Vico introduced the cast — including Margot Robbie, America Ferrera, and Emma Mackey — to milk-thistle tea, which is popular in Croatia, her native country. Vico told Vogue that milk thistle can help cleanse the liver and make the skin "more radiant."

Research in mice suggests that milk thistle can support skin, liver, and bone health, as well as reduce cholesterol and support weight loss. But milk thistle can also interact with certain medication — including for anxiety, allergies, and cancer — as well as birth control, and should always be discussed first with a doctor.

Vico said the tea includes the spiky heart of milk thistle, which needs to be brewed for 20 minutes to achieve its bitter taste.

The tea was such a hit among the "Barbie" stars that Robbie even brewed some for her cast members during their legendary sleepover.

In addition to her facial treatments, Vico created a specialized skin and wellness routine for each of the stars to follow during filming and had them drink kefir and goat milk to improve their balance of gut bacteria.

"I gave Margot kefir and advised her to eat lots of fermented foods, like sauerkraut, for example," Vico told Vogue. "She loved all of that."

And whenever the stars had any blemishes, Vico had a special trick.

"Always use salicylic acid and ice," she said. "Ice reduces the heat and inflammation, then salicylic acid helps unclog the pores."