Oral vitamin D supplementation can achieve the potential benefits of vitamin D, including reducing cancer mortality.

“It must also be emphasized that the beneficial effects vitamin D including the potential of reducing cancer mortality can be perfectly obtained from oral supplementation, the claim of superiority of biosynthesized “sun-made” vitamin D over oral supplementation - while somewhat popular on social media - has not been scientifically backed. It actually has failed clinical testing, like in this meta-analysis showing that only supplementation succeeded in improving serum vitamin D levels[9].”