Welcome @pego. It does seem counter-intuitive doesn't it? One would think that an immune booster would help the healing process. That may not be the case with immunotherapy and some supplements. Supplements as well as other medications can change factors such as absorption, distribution, metabolism and elimination of the cancer treatment.

Antioxidants are taken by many cancer patients because it is thought that the substances will protect and repair healthy cells damaged by cancer therapy. However, there is insufficient information for many specific antioxidant supplements to determine if they are safe and effective as a complementary therapy to standard cancer treatment.

Here is more information:
- Cancer Therapy Interactions With Foods and Dietary Supplements https://www.cancer.gov/about-cancer/treatment/cam/patient/dietary-interactions-pdq

Peg, I can tell that you want to do everything in your power to promote healing and give yourself the best options. To make sure the immunotherapy does its job, it sounds like you should put aside some of the supplements you're used to taking for the time your on treatment.

Here's an article that might help you to work with diet to do your part.
- Diet plays an important role in the success of immunotherapy https://www.news-medical.net/news/20221010/Diet-plays-an-important-role-in-the-success-of-immunotherapy.aspx

I might also recommend talking with an oncology nutritionist and your pharmacist about interactions with immunotherapy and supplements. Perhaps there are some you can continue to take. Have you even met with a cancer nutritionist or dietitian?