Check to see if column exists in the table being edited

I want to add code for updating a couple columns like date modified.
I would like to add the code to all my before update events, even if the table doesn't currently have a date modified column in it.
That was if I eventually add a date modified column it will automatically work.

Is there a way to check to see if a column exists in my table during before add and before update events?

Thanks
Alan