More comments come in and this one is yet another example of why Vitamin D is not a small isolated issue.
This article and podcast is music to my ears! - emeritus Professor Mary Marshall and myself have edited, including writing some chapters, a book called 'Designing Outdoor Spaces for People with Dementia', just published jointly by the Dementia Services Development Centre (DSDC) at the University of Stirling and HammondCare, Sydney, Australia. One chapter specifically notes the need for Vitamin D, based on the available research - and the lack specifically of vitamin D in older people in Care Homes, as they do not get outside often enough - if at all.
Annie Pollock, Architect and Director of Landscape Design, DSDC