[Filligree]

Unless you spend literally hours outside every day, it's not likely to be enough.

Get some cod liver oil, drink a tablespoon every day. Does wonders.

[hanoz]

I heard British prof Steve Jones on the radio recently say that 15 minutes in the middle of the day was enough at this time of year.

[xkapastel]

Posts like this really need to specify what type of person they are talking about. 15 minutes is very clearly not enough for someone with dark skin.