I frequently wonder whether I can stop taking vitamins. Right now I wonder that about "collagen peptide powder" and "hyaluronic acid", but last winter I didn't get any cracks in my fingertips and I'm not sure why, but maybe because of one of these, so maybe they do help.
Some months ago I'd decided to take only half as much iron (from 10 mg down to 5 mg) and half as much B12 because I figured I didn't need as much as I was taking. Then after a month or so I was out on a walk and got all weak and had to sit down. The only thing that had been different that day was I'd had Lima beans the night before, so I researched Lima beans and decided I'd poisoned myself. But then a few weeks later I had another experience of the weakness after using my treadmill.
Then I remembered that 5 years ago I'd been experiencing weakness after using the treadmill and it had taken me most of a year of experimentation (after first going to the doctor and getting EKG and treadmill stress tests that were OK) and what had finally worked for my weakness was adding all three of salt, iron, and B12.
So I reverted to taking the amounts I had been, and I haven't had any weakness problems. Still trying to get up the courage to eat Lima beans again (bought some, they are waiting in the freezer for me to become brave).