The best way to store date/time in MySQL for use with 'date' helper?

[eluser]Dan Murfitt[/eluser]
Hi

I just wondered what people are using to store times/dates in MySQL for use with the CI 'date' helper?

I'm building a site with user specific timezone support, so I need to use the gmt_to_local() function. Normally I would use 'datetime', but I'd have to convert the datetime string back to a unix timestamp every time, so maybe int(11) would be better?

Any advice on this appreciated

Many thanks
Dan