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
Kent County is a county located in the U.S. state of Michigan. As of the 2010 census, the county had a population of 602,622. Its county seat is Grand Rapids. The county was set off in 1831, and organized in 1836. It is named for New York jurist and legal scholar James Kent, who represented the Michigan Territory in its dispute with Ohio over the Toledo Strip.