The theory that solar ultraviolet radiation — and by extension, vitamin D,
which is produced when such radiation strikes your skin — is a potent cancer
fighter satisfies most, if not all, of the criteria. From a scientific point of
view, therefore, vitamin D reduces the risk of many forms of cancer and
increases survival rates once cancer reaches a detectable stage.
…
Supplement users also tend to place an emphasis on health as a priority in their
own personal lives, as reflected in their day-to-day habits when it comes to
maintaining overall wellness. …