@masha123 , My neurologist just informed me last week that too much B6 or B12 can also cause neuropathy, and sure enough, Dr. Google confirms it:
https://www.tga.gov.au/news/safety-alerts/health-supplements-containing-vitamin-b6-can-cause-peripheral-neuropathy
https://www.ncbi.nlm.nih.gov/books/NBK554500/
https://www.houstonchronicle.com/lifestyle/renew-houston/health/article/Massive-doses-of-vitamin-B12-can-be-bad-for-you-17302851.php

Antioxidants (high levels of Vitamin E, Vitamin C, coenzyme Q, tumeric, and many others) have the potential of reducing the efficacy of cisplatin. In addition, many of these components can add to any bleeding risk, and should be held if your platelets are low (good possibility for anyone on gemcitabine, cisplatin and Abraxane).

Quercitin inhibits the activity of enzymes that help break down Abraxane to eliminate it from the body, and could lead to a buildup of the drug (and higher side effects) in your body.

I've also learned that high levels of vitamin B7 (biotin) can cause artificially low CA19-9 readings, depending on the test used.

So, it's definitely worth consulting your oncologist(s) and their pharmacist(s) about any supplements you're considering with the specific chemo you're receiving.

I stopped almost all my supplements a few months ago on my new chemo, and it's a fine line: The chemo seems to be working well (CA19-9 down from 677 to 55), but the neuropathy is adding up quickly. I'm exploring a combination of some quack remedies, and will post if anything good comes of it. 🙂