Your doc will likely have the best answers.
There's some evidence that some vitamins (e.g., Coenzyme q10 and vitamin e) actually help the tumor resist chemo... and there's some evidence that other supplements can reduce side effects (e.g., glutamine) and/or make chemo more effective while providing some protection to your healthy cells (e.g., selenium).
I took a list of the things I was thinking about taking to my onc doc. He "approved" something like 4 of the 6 and recommended against 2 of the six (vitamin e was one of them).
This is a really interesting question because you want to have the strongest body possible during chemo, but you don't want to arm the tumor with any defense against the chemo.
So my recommendation is exactly what the nurse said - althoiugh I don't understand why she would get "curt" - ask your onc. Do some research... ask for recommendations ...
My supplement list is:
glutamine for days 1 - 4 after chemo (three times per day - around 10 g in water)
vitamin B12 (once or twice a week)
vitamin D (we live in the north)
I hope this helps.
Oh - another concern my onc doc had was that if you load up on a bunch of supplements, you might have more problems with digestion (e.g., iron can cause constipation, just like our anti-naus drugs!) and nausea. So holding back a little might prevent exacerbation of problems with nausea....