Lack of any essential mineral nutrient, such as nitrogen, phosphorus, or potassium, in living organisms, which can result in mineral deficiency diseases. In humans, for example, lack of calcium causes poor bone development, and lack of nitrogen can cause the disease kwashiorkor, due to a deficiency in protein intake (see malnutrition). In plants mineral deficiency results in stunted growth and chlorosis. A deficiency of trace elements (see essential element) also leads to diseases; for example, a deficiency of iron can cause anaemia in humans and chlorosis in plants.