Hi Lisa, Lea and Perrins Worcestershire contains (amongst other things) molasses, sugar and salt, which I think are all on the no-no list for sole source, so unfortunately I think you'd be safer not using it
My CDC says it's ok to use herbs and spices, but if you're using a spice blend, e.g. cajun, I'd just check the label to make sure it doesn't have sugar or salt in it etc. Hope that helps. I find that a bit of curry powder helps pep up a lot of the soups