11.9 – Zinc

Learning Objective

  • Explain the role of Zinc in the body.

 

Zinc is a cofactor for over two hundred enzymes in the human body and plays a direct role in RNA, DNA, and protein synthesis. Zinc also is a cofactor for enzymes involved in energy metabolism. As a result of its prominent roles in anabolic and energy metabolism, a zinc deficiency in infants and children blunts growth. The reliance on growth on adequate dietary zinc was discovered in the early 1960s in the Middle East where adolescent nutritional dwarfism was linked to diets containing high amounts of phytate. Cereal grains and some vegetables contain chemicals, one being phytate, which block the absorption of zinc and other minerals in the gut. It is estimated that half of the world’s population has a zinc-deficient diet.1

This is largely a consequence of the lack of red meat and seafood in the diet and reliance on cereal grains as the main dietary staple. In adults, severe zinc deficiency can cause hair loss, diarrhea, skin sores, loss of appetite, and weight loss. Zinc is a required cofactor for an enzyme that synthesizes the heme portion of hemoglobin and severely deficient zinc diets can result in anemia.

1 Prasad, Ananda. “Zinc deficiency.” BMJ 2003 February 22; 326(7386): 409–410. DOI: 10.1136/bmj.326.7386.409. Accessed July 5, 2019.

 

Dietary Reference Intakes for Zinc

Table 11.9.1: Dietary Reference Intakes for Zinc
A table that shows the dietary reference intakes for all age groups
Age Group R.D.A. (milligrams per day) U.L. (milligrams per day)
Infant (0–6 months) 2* 4
Infants (6–12 months) 3 5
Children (1–3 years) 3 7
Children (4–8 years) 5 12
Children (9–13 years) 8 23
Adolescents (14–18 years) 11 (males), 9 (females) 34
Adults (19 + years) 11 (males), 8 (females) 40
Denotes Adequate Intake*
Fact Sheet for Health Professionals: Zinc. National Institute of Health, Office of Dietary Supplements. Updated March 13, 2019. Accessed June 30, 2019.

 

Dietary Sources of Zinc

Table 11.9.2: Zinc Content of Various Foods
A table showing different food sources of Zinc.
Food Serving Zinc (milligram) Percent Daily Value
Oysters 3 oz. 74 493
Beef, chuck roast 3 oz. 7 47
Crab 3 oz. 6.5 43
Lobster 3 oz. 3.4 23
Pork loin 3 oz. 2.9 19
Baked beans ½ c. 2.9 19
Pumpkin Seeds 1 oz. 2.2 15
Yogurt, low fat 8 oz. 1.7 11
Oatmeal, instant 1 packet 1.1 7
Almonds 1 oz. 0.9 6

 

Contributors


University of Hawai’i at Mānoa Food Science and Human Nutrition Program: Allison Calabrese, Cheryl Gibby, Billy Meinke, Marie Kainoa Fialkowski Revilla, and Alan Titchenal