‘So what precisely is kefir?’ I don’t hear you ask. Well according to the top boffins here at Laboratoires Yumblog, kefir is a scientifically proven magic drink packed full of friendly bacteria so affable they’ll transform your stomach into a fragrant wonderland of probiotic loveliness. ‘Hmm, sounds interesting’ you quizzically reply, ‘but by what devilish witchcraft does one contrive this …