Drinking water kept in a glass bottle in direct sunlight all day gives your body vitamin D.

Original review summary

The review says the method cannot provide vitamin D: glass blocks UVB, and vitamin D synthesis occurs in living tissue rather than water. It concludes that UVB must reach bare skin to start the process. The review states, “UVB radiation does not penetrate glass” and that synthesis “only happens in the human body.”[S1]