It wasn't simply cosmetics and facials that helped the "Barbie" ensemble acquire doll-like skin.
Jasmina Vico, a skin health specialist, was in charge of keeping the stars shining on-screen, and she understood the key was more than just skin-deep.
"Everything in the movies is about lighting," Vico, who is based in London, told Vogue. "That's when I realized, OK, let's work on the liver, calm the nervous system,
and make the skin glow." But, most importantly, we're going to concentrate on that light from within."
Vico introduced the cast, which included Margot Robbie, America Ferrera, and Emma Mackey, to milk thistle tea, which is popular in her native Croatia.
"Milk thistle cleanses your liver," she told Vogue. "When that happens, our liver produces more glutathione, which makes the skin look more radiant.
"Vico claims the tea contains the spiky heart of milk thistle, which must be steeped for 20 minutes to achieve its bitter taste.
"Anything bitter helps the liver flush," she adds. "This tea tastes like a witch's brew!" The tea was so popular among the "Barbie" stars that Robbie made some for her cast members during their epic sleepover.