Perhaps for more people would get cancer if they didnt take vit d. It certainly isn’t a cure all, but there seems to be mounting evidence that it can help- perhaps people with low d get cancer far more frequently than people with adequate d levels.
I have been taking supplemental vitamin D (with physician guidance) since long before I got cancer.
Lack of vitamin D causes problems. But surplus of vitamin D is not preventive or curative.
It’s like food. If you don’t get enough, you have problems. But getting too much isn’t healthy, either.
The Goldilocks principle is in full force here.