Orlando Bloom has quit drinking tea because the caffeine content in his favourite brew wreaks havoc on his bad back on movie sets.

The actor, who famously smashed his spine in a fall before his movie career took off, was left in agony during night shoots on new movie ELIZABETHTOWN in rural Kentucky - and he realised it was all because of the tea he drank.

He explains, "I was drinking green tea, which has caffeine. Not an awful lot. Just enough to get me through the shoot.

"By the end of the night, my back was killing me. It (caffeine) dehydrates your spine and my back - that's still my alarm. That's my canary in the mine shaft."