You don t say what kind of supplements you are considering. You need to talk to your oncologists. Even certain supplements and herbal medicines may interact with the chemotherapy you are receiving, so they need to know so they can advise you properly. I would not recommend taking supplements in place of the chemotherapy. If your oncologists thought a supplement such as iron would help with your low RBC count, I am sure they would suggest it. Usually the RBCs are low because of the cancer and chemotherapy and not because of iron deficiency. In that case iron wouldn t help much. Eating good nutritional meals and using food supplements like Ensure may be helpful. Hope this answers your query. If you have more questions, I would be happy to answer them.