Sue,
One thing I am doing to try to keep my immune system strong is to eat BroccoSprouts. These are broccoli sprouts that were developed by John's Hopkins University School of Medicine. Here is the link to their web site that tells about the benefits. They supposedly have much stronger antioxidents than regular grocery store sprouts. They taste slightly spicy like a radish. I just eat mine plain, but they would be fine in salads or on sandwiches. Since these were developed by a major University, I feel there may be some real merit in eating them. Currently I am not on any chemo or Herceptin. Sometimes when you are actively in treatment it is not advised to try to bolster your immune system, as you want the cancer cells to be as vulnerable as possible. Check with your oncologist. Hope this link works for you.
www.broccosprouts.com/default.asp