Milk is not complete food because it deficient in

Milk is not complete food because it is deficient in Iron.
Milk contains all the vitamins and minerals necessary to sustain growth and development. It provides almost every single nutrient needed by humans making it one of the most nutritious foods available.
Milk in itself as it contains a lot of important nutrients, including a few that most people don't get enough of like protein. But milk is not complete food as it lacks vitamin C and Iron.