I defy you to guess what this paragraph is about. I have put a sentence in bold to help you out.

Zinc is essential to proper growth and development, sexual maturation, wound healing, and it may play a role in immune system function and other physiological processes. Zinc assists several hormones involved in reproduction, it is required for DNA, RNA, and protein synthesis, and is a cofactor for many enzymes involved in most major metabolic processes (Flynn, 1992; Picciano, 2000; Guo and Hendricks, 2007). Human zinc deficiency was first reported in the 1960s in the Middle East, resulting in dwarfism, impaired sexual development, and anemia. It is difficult to detect mild deficiencies of zinc, although they have been shown to occur in Western countries, especially in infants and children, and give rise to suboptimal growth, poor appetite, impaired taste acuity, and low hair zinc levels. Mean zinc concentration in mature human milk during the first six months of lactation is about 2 mg/L, although large variations in zinc have been reported at 0.65 - 5.3 mg/L. Dietary zinc intake has no correlation to zinc content of human milk, and zinc supplementation of a zinc adequate diet does not significantly affect human milk zinc concentration. Zinc in human milk is found in three major components: serum albumin (Figure 2.6. National Center for Biotechnology Information, 2010.) and citrate in the whey, and in alkaline phosphatase in the fat globule membrane.