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
Cass County, Michigan (MI) County population in 2014: 51,608 (29% urban, 71% rural); it was 51,104 in 2000. County owner-occupied with a mortgage or a loan houses and condos in 2010: 10,660. County owner-occupied free and clear houses and condos in 2010: 5,848. County owner-occupied houses and condos in 2000: 16,114.