Concerns raised over Britney Spears' caffeine intake and safety.

Britney Spears allegedly consumes large amounts of caffeine, including Red Bull, Celsius, coffee, and dandelion tea, according to a new documentary by TMZ. Experts suggest that those with mental illness often crave the high they get from caffeine, though it's not healthy or great for them. The documentary, "TMZ Investigates: Britney Spears: The Price of Freedom," explores the singer's life since her conservatorship ended a year and a half ago, including her relationships with her family and kids, her marriage to Sam Ashgari, and concerns from those closest to her. The hour-long doc airs on May 15 at 9 p.m. ET on Fox.