It could cure any 'female ailment' - even cancer - said the adverts. But Lydia E. Pinkham’s Vegetable Compound was, in fact, just a concoction of herbs and alcohol of no proven medicinal merit. That didn't stop desperate American women from buying bottles of the stuff - and writing to Lydia Pinkham for medical advice.   Why did her customers shun 'expert' doctors and opt instead for quack medicines? And why, when Lydia Pinkham finally came in for criticism, did no one question the efficacy of her vegetable compound?   For a full list of sources for this episode, go to timharford.com. See omnystudio.com/listener for privacy information.