Laravel 5.6 - Only save value if it has changed

I have a Laravel 5.6 project and am trying to update a post from a form like this

<input name="email" type="text" class="form-control" placeholder="Email" value="" required>

In my PostsController I have this...

    if($request->input('email')) {
        $user->email = $request->input('email');
    }

I wanted it to only update the email if a new one has been input in the form, but because I am pre-populating the form fields it always passes the IF.

Is there a more Laravel way to do this? I have looked at isDirty() but I am not sure it is the correct thing to use.

via Chebli Mohamed