Jessica Stam, Bregje Heinen, and Karlie Kloss among others. Maybe it's because there's no better spokesperson than Caroline Trentini. From her Top Shelf:

'My hair is in the best shape ever thanks to Julien [d’Ys]—he told me to take Viviscal. I used to have such thin hair, because of genetics but also because I used to do so many shows, and it wouldn’t grow. Viviscal is a miracle. But you have to stick with it—I’ve been taking it for five years, and my hair’s never been so long. Thank God—or, thank Julien—for Viviscal. I tell everybody about it.”

From the mouths of babes...

Photographed by Emily Weiss.