In order to prevent the cancer from returning, I follow a plant-based diet. I didn't check the B12 level, but a plant-based diet is unfortunately associated with a B12 deficiency. Here in Hungary, doctors say that cancer patients should not take vitamin B12, but nowhere does it describe why.

I don't know anything about collagen but my doctors prescribed B12 and B complex so I take both.

My medical oncologist said that I could take it.

I would make sure that you need the B12. Has your blood tests shown it low?

There are not definitive guidelines on collagen. Ask your doctor if ok to take…Go from there.

I was told by my oncologist that I should not take collagen as it could interfere with the hormone treatment that I am on (Anastrazole) it is an AI Aromarade Inhibitor.,