Pills that can help a person reverse the effects of aging could be on the market in the next five years, according to an expert.

Sam Altman, 37, was revealed to have funded biotech startup Retro BioScience to the tune of $180million last month. He is the latest in a long line of Silicon Valley billionaires to throw their considerable wealth behind the science of aging. 

Amazon's Jeff Bezos is reported to have invested $3billion in life-extension startup Altos Labs. PayPal co-founder Peter Thiel invested in the Methuselah Foundation, which has the goal of making '90 the new 50'.