Some MPs hid their mental health problems because they were afraid they could never get elected to Parliament, according to Vince Cable.
The business secretary told IBTimes UK mental health issues were "suppressed" for a "very long time" in Westminster. House of Commons rules meant MPs detained under the Mental Health Act for more than six months would be stripped of their seat.
But Cable said Parliament has witnessed a culture change and now politicians are more open about their mental health issues. "There's a recognition that this is a serious issue in Parliament. It's been suppressed for a very long time and you may know the reason," the Liberal Democrat MP said.
"There are two reasons why you can't be elected to Parliament: One of them is criminality and the other is a mental illness. People probably kept this hidden but it's now confronted openly. Quite a lot of MPs have had stress and depression.
"The House of Commons' authorities have recognised that this is a service that needs to be provided."
MPs voted on an annual budget of £25,000 (€35,473, $37,542) to help MPs with mental health issues in 2013. John Thurso MP, the spokesman for the Commons Members Estimate Committee, warned the work of an MP brings "particular stresses".
"All conscientious employers want to help those with mental health issues and often assistance in accessing help is the first vital step," Thurso argued.
"Being an MP is a privilege but brings particular stresses as we heard in the debate in June. It is therefore appropriate for us to take this initiative to assist members to access the help they need."
Cable made the comments after a speech on mental health issues in the workplace at an event hosted by the CentreForum think tank.
The business secretary shared his personal experience of mental health illness, explaining his mother, Edith, had suffered from postnatal depression.
"When I was 11, my mother had a nervous breakdown. I don't think people at that stage understood postnatal depression and she was sent off to a mental institution," he said.
"It was referred to as 'The Loony Bin'. That's how you talked about those things in those ways – very despairingly. She was eventually cured and had no further relapse as a result to the productive experience she had going into adult education."
Cable championed adult education at colleges as a way of helping people with mental health problems. The minister explained the government's £5m adult education college scheme will be assessed to see what benefits they can give to people with mental health issues.