Table 4.

How Hill's criteria for causality in a biological system are satisfied for solar UVB and vitamin D and cancer

Factor	How satisfied	References
Strength of association	Ecological studies; observational studies of breast and colorectal cancer	3–43
Consistency	Ecological studies	3–39
Temporality	Observational studies	17, 39–43
Biological gradient	Dose-response for serum 25OHD for breast and colorectal cancer	40–43
Coherence (mechanisms)	Effects on cells, antiangiogenesis, antimetastasis, calcium absorption, immune system strengthening	81–83
Experiment	Randomized controlled trial	85
Analogy	Geographical variation of mortality rates for various cancers	3–39
Rule out confounding factors	Ecological studies	3–39
Avoid bias	IARC	79, 80