The Dutchman has come in for a huge amount of criticism over the last few months, with fans and pundits alike growing frustrated with the football being played by United.
The Red Devils have not scored a first-half goal at Old Trafford in 11 games and have slipped out of the top four in recent weeks.
Henry feels that change is now necessary, claiming that Van Gaal is struggling to get his ideas across.
"I know a lot of United fans and all they talk about is how poorly their team are playing," Henry wrote in his Sun on Sunday column. "It’s not about results any more. Even when they win, the issue is still how awful the football is. They don’t enjoy watching their team any more. They are bored.
