Bryan Johnson, a data-obsessed Silicon Valley centimillionaire, is promoting food and supplements that promise to help people live longer. Scientists say his program is highly questionable. So why are ...

‘But only one of them was a saffron-robed guru,’ he says, smiling. ‘The optics of that were promising because I knew our audience would prefer to learn from a sanyasi.’ Karamveer, Ramdev’s mentor, had ...