Having had chemo treatments myself and cared for my husband during his, my experience is that oncologists do not want you on any supplements unless they specifically approve it. Apparently, many supplements can interfere with chemo, and that tends to be their main focus of oncologists. My husband had chemo prior to surgery, so this was not an issue for him, but after the Whipple he was told he needed to take AQUADEK's for the rest of his life, and he has been taking it for the past 5+ years. Recently, he was hospitalized for a stroke, during which lab results showed that his vitamin D level was below normal, so apparently he should take more. Despite this finding, when he was getting discharged, the medication changes stated that he should discontinue his vitamins and minerals. When I questioned this change, the doctor's response was "well, those are just vitamins. They are not important, but if he wants to he can take them." (Apparently, he was not given these vitamins, even though I supplied them on account of the hospital pharmacy not carrying.) Even when I tried to explain to this "doctor" why it IS important for my husband to take these vitamins, he kept saying that it's his choice to take IF he wants to. this was one of several reminders in the past years that we have to be actively involved in our healthcare. Keep asking questions until you find the answers that makes sense for your situation!