Food mixture or ingredient sources for dietary calcium: shifts in food group contributions using four grouping protocols.

Identifying dietary sources of nutrients by assigning survey foods to food groups can under- or overestimate the contribution a group makes to the intake of specific nutrients. Using calcium and food intakes from USDA's 1994-1996, 1998 Continuing Survey of Food Intakes by Individuals, the authors determined the proportion of dietary calcium from the dairy, grains, meats, fruits, and vegetables groups using four grouping protocols. Calcium contributions from milk and cheese were higher as more ingredient sources and fewer survey food items were represented in the dairy group. Milk, cheese, and yogurt reported as separate survey food items contributed 42% of total calcium intake. An additional 21% of dietary calcium came from dairy ingredients in mixed foods such as macaroni and cheese, pizza, sandwiches, and desserts. The remaining dietary calcium sources were single grains (16%); vegetable (7%); meat, poultry, and fish (5%); fruit (3%); and miscellaneous foods (7%). Data quantifying the nutrient contributions from dairy ingredients could affect dietary guidance messages or research using dairy foods as variables.