Ну вот найдите мне. гуглила тутhttps://www.google.ca/search?q=vitamin+d+from+sun+in+winter&ie=utf-8&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&gfe_rd=ctrl&ei=z0IjU43SGIeN8QexlYDIBw&gws_rd=cr