Answer:The two My Plate food groups that are the major contributors of iron, thiamine, and niacin are the protein foods group and the grains group.
Protein foods such as meat, poultry, fish, beans, peas, and nuts are rich sources of iron, thiamine, and niacin. Whole and enriched grains, such as whole wheat bread, brown rice, and fortified cereals, are also good sources of these nutrients.
While a child's iron intake can be an indicator of their overall nutrient intake, it is not safe to assume that if a child's iron intake is adequate, their thiamine and niacin needs are also being met. While these nutrients are often found in the same foods as iron, there can be variations in their amounts and bioavailability. Moreover, the requirements for these nutrients may differ based on the child's age, sex, activity level, and overall health status. Therefore, it is important to ensure that a child's diet is diverse and balanced, providing a variety of nutrient-dense foods from all the food groups to meet their daily nutrient needs.
Step-by-step explanation: