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
Livingston County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 180,967. The county seat and most populous city is Howell. The county was set off in 1833, but for three years remained a part of Shiawassee and Washtenaw counties. It was organized in 1836. As one of Michigan's Cabinet counties, a group of counties whose names honor members of President Andrew Jackson's Cabinet, it is named after former U.S. Secretary of State Edward Livingston. Livingston County is included in the Detroit-Warren-Dearborn, MI Metropolitan Statistical Area.