Firstly, I welcome your input. This, like every topic, benefits from informed discussion.
As far as I can tell, that vitamin C causes kidney stones was an assumption not verified. Mega-doses of anything seems a bad idea to me unless targeted at some specific condition.
Near all I’ve read about vitamin D leads me to believe that few of us will get adequate amounts without supplementation.
I’m one of those people described as taking a muti-vitamin, mineral, etc. pill as ‘insurance’ against inadequacy in diet. The pill I take has no mega-doses of anything.
The damage caused by excessive doses of vitamin C and other water-soluble vitamins isn’t so much kidney stones, but deposits of oxalate (or other) crystals in the kidney tubules and other organs. Furthermore, the process of straining the excess vitamin C out of the blood puts needless wear-and-tear on the kidneys.
Given the huge profits of the vitamin industry, I would take anything claiming that you can’t get adequate amounts of whatever nutrient from your diet or normal activities with a huge grain of salt. It makes no sense at all to believe that we evolved to need higher doses of trace nutrients from our diet than we can get through our natural activities. Our diets are far more varied than those of our ancestors, meaning that the likelihood of missing essential nutrients (as long as we make an effort to “eat healthy”) is far lower than what our ancestors faced.