For instance in the UK: > At latitudes below 37ᵒN, UVB radiation is sufficient for year round vitamin D synthesis. At higher latitude, vitamin D is not synthes

For instance in the UK: > At latitudes below 37ᵒN, UVB radiation is sufficient for year round vitamin D synthesis. At higher latitude, vitamin D is not synthesised during the winter months. In the UK, sunlight-induced vitamin D synthesis is only effective between late March/early April and September and not from October onwards throughout the winter months. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/537616/SACN_Vitamin_D_and_Health_report.pdf https://assets.publishing.service.gov.uk/government/uploads/...