Claim: Alexandre Paiva (born 1967) began training when he was 15 years old and won the World Jiu-Jitsu Championship.
Evidence: Alexandre "Gigi" Paiva (born March 4, 1967, Rio de Janeiro, Brazil) is a long standing figure, having been involved in Jiu Jitsu since the early 1980s, in the Brazilian jiu-jitsu community who has made a number of important contributions to the sport which are referenced below. He began training when he was 15 years old in Romero "Jacare" Cavalcanti's school, where he was considered to be one of the academy's most technically gifted students, and received his Black Belt in 1993. In addition to being an outstanding competitive athlete winning the World Jiu-Jitsu Championship 1x at Adult level and 4x at Masters level he also, alongside Romero "Jacare" Cavalcanti and Fabio Gurgel, co-founded the Alliance Jiu Jitsu Team which has gone on to become the most successful competitive Brazilian Jiu-Jitsu team of all time. 
(1967-03-04) March 4, 1967 (age 53) World Championship Brazilian Jiu-Jitsu