Because they are aside from the nervous system, the most important systems in your body. Without these systems you would not be able to circulate nutrients, expel and transport wastes like CO2, And just about keep you alive. In healthcare, you come to know that without a heart beat or an airway, your patient will die.
Items that belong to the five food groups in the USDA's MyPlate Food Guidance System are:
Veggies
Fruits
Dairy
Protein
Grains
so any one of them could be considered as one of the five food groups
Hope this helps :)
