Vitamin D2 and vitamin D3 are the forms of vitamin D most important to human health, according to the Mayo Clinic. Vitamin D2 is manufactured by plants, while vitamin D3 is manufactured in the skin when it's exposed to the sun.
Population in families living in Washtenaw County ; Total Population: 238,069; Population Under 18 years: 70,878; Population 18 years and over: 167,191
Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County. The 2010 census recorded its population to be 113,934, making it the sixth largest city in Michigan. The city's population was estimated at 117,070 as of July 2015 by the U.S. Census Bureau.