TV psychologist Nigel Latta is under fire for his use of the word mental.

In his Politically Incorrect Parenting Show on TV One, Latta explained teenagers' behaviour by describing them as "mental" and "not right in the head".

Christopher Banks, 33, who has bipolar disorder, argued Latta was in breach of the TV broadcasting code by encouraging discrimination.

On his blog, he accused Latta of damaging public perceptions of mental health.

"It ticks off every stereotype in the book. It's a step too far and ill-considered."

Mental illness affects one in five New Zealanders. Banks, who works for the Mental Health Foundation, was diagnosed with bipolar disorder three years ago following a bout of severe depression.

He said Latta's explanation could cause parents to miss signs that their children were suffering from mental illness.

TVNZ and Latta said no offence was intended and viewers understood that.

A statement said Latta had "the greatest concern for people who have genuine mental health issues".

"The intent of his show is not to denigrate anybody or anything, but to help and to educate using humour and, from time to time, exaggerations for effect."

It said time constraints forced the following comments to be cut from the show: "Now I'm not for a moment disparaging or in any way downplaying the sufferings of families when the kids have actual psychiatric illness because that's terrible and there's a big stress on families."

Banks accused Latta's show of being deliberately provocative to attract viewers.

He planned to make a formal complaint about the show and encouraged others to do so.

TVNZ has received two complaints accusing the show of "denigrating" teenagers.