I finished Chemo and radiotherapy five months ago.During treatment I was advised not to have prebiotic foods or over the counter supplements.Thankfully I have been given the all clear.Could I take a collagen supplement to help with hair and bone issues and are probiotics OK. I am concerned that I have read online that collagen feeds cancer. Also I have stiff joints which may be due to the pelvic radiotherapy, can I take a vitamin supplement to help with this. I do try to follow a healthy diet. Thank you.