Which of elements is lacking in milk?

The element that is lacking in milk is iron. Iron is an essential mineral that is required for the production of hemoglobin, which is a protein in red blood cells that carries oxygen. Milk is a good source of many nutrients, but it is low in iron. This is why it is important for infants and children to consume other foods that are rich in iron, such as meat, poultry, fish, eggs, beans, and dark leafy greens.