Poor nutritional intake, chronic or acute health conditions, drugs, changed nutrient metabolism, or a combination of these variables can cause nutrient deficiencies or disorders, which can affect the levels of macronutrients and micronutrients in the body. If the deficiency occurs during foetal development or early childhood, it can cause changes in energy metabolism, immunological function, cognitive function, bone formation, and/or muscular function, as well as growth and development. Deficiencies, excesses, and imbalances in the cell's nutrition all predispose it to harm. Individual dietary habits can result in nutritional deficiency or deficiency in the broader population. Anemia, for example, is one of the disorders induced by nutritional deficiencies. Vitamins are necessary for the body to keep healthy and perform correctly. In the developing world, nutritional deficiency is a major issue.