The food purchased with WIC vouchers must be on the approved list of approved foods. Up until 2005, the list of approved foods was meant to help supplement participant's diets to contain the following priority nutrients: protein, calcium, iron, and vitamins A and C. The literature stated that from the initiation of WIC in 1972 until 2005, the monthly food packages provided by WIC remained largely unchanged despite advances in nutrition knowledge, changes in dietary patterns, increased cultural diversity among WIC participants, and a nationwide epidemic of obesity.