* Often hard to live up to expectations of sainthood
* No age limit for winners; Malala just 16
By Alister Doyle and Balazs Koranyi
OSLO, Oct 9 (Reuters) - Alongside the glory, the Nobel Peace Prize has a darker side likely to make the awards committee think hard before honouring a Pakistani teenage activist shot by the Taliban who is favourite to win on Friday.
The prize has changed the lives of presidents, freedom fighters or humble human rights workers but some winners say it is hard to be put on a lifelong pedestal where actions, flaws and foibles can get judged against a yardstick of sainthood.
This year that flip side of fame is more relevant than ever because Malala Yousafzai, shot in the head by the Taliban a year ago on Wednesday for demanding education for girls, is just 16.
All other winners have made career choices as adults. She would be half the age of the youngest winner of the award since it was set up in 1901 - Tawakul Karman, a Yemeni peace activist, was 32 when she shared the prize in 2011.
Geir Lundestad, who hosts and attends the meetings of the peace committee as director of the Norwegian Nobel Institute, says there is no age limit.
"It will transform their lives," he said of new laureates.
"They will be flooded by invitations. They will be listened to, and some of them may even be considered saints," he said. "But I haven't met anyone yet who regrets being selected for the Nobel Peace Prize."
This year there are a record 259 nominees but Yousafzai has been widely nominated. The committee of five, usually political appointees from Norway's top parties, whittles them down before picking a winner from a shortlist which is not made public.
Jody Williams, who won a share of the prize as coordinator for the campaign to ban anti-personnel landmines in 1997, is outspoken about the downsides, writing in a 2013 autobiography that winning "hasn't been all joy and wonder".
Some people seem to imagine a Nobel Prize transforms winners "into something resembling a saintly creature. It's rather frightening actually," she wrote, adding she was poles apart from Mother Teresa, the 1979 winner who was beatified in 2003.
Any loose remark can be picked over and magnified, she said. On the day she won, for instance, she said it might have been a mistake to call then U.S. President Bill Clinton a "weenie" for failing to sign up to the landmine treaty.
Kristian Harpviken, head of the independent Peace Research Institute Oslo, said Yousafzai was his top pick for this year's $1.25 million prize. She is also the bookmakers' favourite and widely tipped by Norwegian media.
"The main question about Malala is her age," he said.
He said he believed the prize would only marginally affect the risks that Yousafzai, who is now in England, might again be a target for the Taliban.
But he added: "The other aspect is of course to burden somebody, who is still basically a child, with having to carry the weight of a Nobel Prize for the rest of her lifetime, and that, admittedly, is tough call."
Rajendra Pachauri, the Indian chair of the U.N.'s panel of climate scientists which shared the 2007 award with former U.S. vice-president and climate campaigner Al Gore, said the prize had generally been a huge benefit despite the media microscope.
"You get an enormous amount of scrutiny from the public and the media. There are of course upside and downsides of that," he said. "In some senses it brought climate change scientists closer together."
Lundestad, an authority on the prize because he has been the committee's secretary for 23 years, said the five members were acutely aware of candidates' desires and risks - especially Liu Xiaobo, a jailed Chinese dissident who won in 2010.
The committee discussed "can you give the prize to Liu Xiaobo when you know that the short-term impact will most likely be negative for him personally? This is a very deep moral question. It was the committee's strong impression that he did want the prize," he said.
Other candidates mentioned this year include Denis Mukwege, a Congolese gynaecologist who helps survivors of sexual violence, and Bradley Manning, a U.S. soldier convicted of leaking secret files to WikiLeaks.
Thousands of people have the right to nominate people for the award - including members of every national parliament in the world and university professors of history, philosophy or law. "It's very easy to get nominated," Lundestad said.
He said many people wrongly believed that getting nominated was a sign of endorsement by the committee - yet even Hitler once made it to the list.
"If someone outrageous is being nominated for the prize I will come to work the day after and find hundreds of e-mail messages," he said. "And they will all say: "you idiot".