Scrum-half White, full-back Olowofela and forward Lewis have all been selected in this season’s England Under-20s squad ahead of the Under-20s Six Nations Championship and World Junior Championship.
All three have gained senior experience with Tigers this season as well as playing in the Premiership ‘A’ League and out on loan at Loughborough Students.
They are joined in agreeing new contract terms at Tigers by hooker Harry Mahoney, scrum-half Harry Simmons and back-rower Fred Tuilagi.
Terms have also been agreed with former England Under-20s caps Charlie Thacker and George Worth.
Thacker, following his dad Troy and older brother Harry into the Tigers ranks, scored his first senior try in the Anglo-Welsh Cup win over Gloucester earlier this season and made his European Champions Cup debut in the game away to Castres Olympique this month.
Worth enjoyed a breakthrough season in 2016/17 when he played in the European Champions Cup and Aviva Premiership as well as starting the Anglo-Welsh Cup Final victory.
Tigers head coach Matt O’Connor said: “We firmly believe that the club is at its strongest with a core of homegrown players in the squad. We invest a lot of time and resource into the academy at Tigers with the aim of producing players who can step up to first-team level.
“These guys have shown good progress through the ranks and all hope to emulate the achievements of guys like Tom and Ben Youngs, Dan Cole, Tom Croft, Manu Tuilagi and Matt Smith in coming through the academy here to play consistently at the very top levels of the game.”