Fundamentals of Human Nutrition/Zinc

11.2 Zinc

Zinc is a trace mineral essential for the health of the human body. It has several roles in metabolism and immune function and it is needed to produce retinal, the active form of vitamin A. It is also a key factor in the growth and development of children and it affects behavior and perception of taste. In the U.S., it is recommended that men over 19 years of age consume 11 milligrams per day, and 8 milligrams per day for women (“Zinc Fact”). The upper limit is set to 40 milligrams. If an adult consumes more than 40 milligrams of zinc per day, it can lead to a copper deficiency, which can, in turn, lead to the degeneration of the heart muscle (Whitney& Rolfes, 2013).

References

Whitney, E. N., & Rolfes, S. R. (2013). Understanding nutrition (13th ed.). Belmont, CA: Thomson/Wadsworth.

Zinc Fact Sheet for Health Professionals. (n.d.). Retrieved December 1, 2015, from https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/

11.2.1 Sources

The best sources of zinc are plain yogurt, ground beef, oysters, broccoli, lean sirloin steak, and crab. These foods provide the best sources per kilocalorie. Foods rich in protein have the highest amount of zinc. A few other sources include peanuts, sunflower seeds, and pinto beans. When eaten in large quantities, whole grains and legumes can be great sources of zinc. It is important to note that phytates inhibit the absorption of dietary zinc. Phytates are found in whole grain breads, legumes, cereals, and other grains. These plant and grain-based foods are still good sources of zinc, but the zinc in these foods is not as bioavailable compared to that of animal foods (Whitney & Rolfes, 2013).

References

Whitney, E. N., & Rolfes, S. R. (2013). Understanding nutrition (13th ed.). Belmont, CA: Thomson/Wadsworth.

11.2.2 Functions

Zinc and its Functions

Zinc is an essential trace mineral. Zinc is found in seafood, red meat, beans, turkey, yogurt, bran most protein and fortified products. Zincs functions include cell reproduction, cell growth, metabolism, immune function and many more.This trace mineral is proven its most important during childhood and pregnancy due to its contribution to the growth and development of the human body. Zin also assists in common functions such as sight and smell. However, Zinc has three main functions which include supporting the immune system, metabolism and cell replication. Without Zinc, your body will suffer much turmoil.

Immune System

Research shows that if consumed regularly, Zinc can reduce the chance of one getting the common cold. Zinc Deficiency foremost impacts the human immune system. It works towards three factors within the immune system. Zinc fights away pathogens, immune cell function and is a messenger in transduction. (Haase and Rink, 2014) Just a single dietary supplement, when experiencing the common cold will reduce the long lasting symptoms and decreases the severity of those symptoms. (Sarubin Fragaakis A, 2007) Lack of Zinc can lead to more infections, acne, and more illnesses.

Metabolism and Zinc

Zinc plays a huge role in metabolism. It assists in bone metabolism which is why it is such a great contributor to bone development. People who suffer from zinc deficiency also suffer from growth defects or osteoporosis because their bones are not getting ample support nor development. Zinc also modifies the metabolism of cGMP and transcription factor MTF-1 which all together assists in gene transcription and development of protein kinase C. Zinc also assist in the metabolism of Vitamin A. This fat soluble vitamins functions are storage and use of insulin, vision, growth, reproduction and healthy skin.

Cell Proliferation

Zinc is vital in cell proliferation, which means that it assist in cell growth and division. This includes the synthesis of DNA and mitosis. It assists in the transcription of proteins and enzymes. Zinc is essentially on the building blocks for cells and protein of the human body. (Beyersmann and Haase, 2001) This is important because proteins are what build bones, skin, muscles and blood, all of which pertain to and are essential to the human body. Zinc Fingers are also essential in the process of cell proliferation, one percent of DNA is found in these structures. ZInc Fingers are essentially finger like protrusions that assist in transcription factors. .

Zinc Deficiency

Zinc clearly contributes a lot to our well being. If not consumed to the necessary amount it can cause a Zinc deficiency. This could entail possible deficiencies such as sickle cell anemia, dwarfism, night blindness and even mental health problems. Symptoms include hair loss, loss of appetite, impaired taste buds and low hormone synthesis.

References Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press. Washington, DC: 2001. PMID 25057538.http://www.ncbi.nlm.nih.gov/pubmed/25057538

Beyersmann, D., & Haase, H. (2001). Functions of zinc in signaling, proliferation and differentiation of mammalian cells. Biometals, 14(3-4), 331-341. doi:10.1023/A:1012905406548

Evert, A. (2013, February 2). ZInc in Diet. The New York Times. Retrieved November 25, 2015, from http://www.nytimes.com/health/guides/nutrition/zinc-in-diet/overview.html

Haase, H., & Rink, L. (2014). Multiple impacts of zinc on immune function. Metallomics, 2014(6), 1175-1180. doi:10.1039/C3MT00353A

Sarubin Fragaakis A, Thomson C. The Health Professional's Guide to Popular Dietary Supplements . 3rd ed. Chicago, Il: American Dietetic Association;2007.

11.2.3 Requirements

The table below provides the Dietary Reference Intakes for Zinc (Otten, Hellwig & Meyers, 2006).

	EAR (mg/day)		RDA (mg/day)		AI (mg/day)	UL (mg/day)
Age	males	females	males	females
0–6 months					2	4
7–12 months	2.5	2.5	3	3		5
1–3 years	2.5	2.5	3	3		7
4–8 years	4.0	4.0	5	5		12
9–13 years	7.0	7.0	8	8		23
14–18 years	8.5	7.3	11	9		34
19–50 years	9.4	6.8	11	8		40
≥ 51 years	9.4	6.8	11	8		40
Pregnancy
14–18 years		10.5		12		34
19–50 years		9.5		11		40
Lactation
14–18 years		10.9		13		34
19–50 years		10.4		12		40
EAR = Estimated Average Requirement RDA = Recommended Dietary Allowance AI = Adequate Intake UL = Tolerable Upper Intake Level

References

Otten, J. J., Hellwig, J. P., & Meyers, L. D. (2006). Dietary reference intakes: The essential guide to nutrient requirements. National Academies Press. Retrieved from http://www.nap.edu/catalog/11537.html

11.2.4 Imbalance

The main symptoms of zinc deficiency include growth retardation, impaired immune function, and loss of appetite. Children have the highest need for zinc because they are undergoing rapid growth. Children in developing countries often suffer from a zinc deficiency and will have stunted growth. In addition, because zinc is required to produce the active form of vitamin A, vision impairments have been linked to zinc deficiency. Adults should not consume more than 40 milligrams of zinc per day (“Zinc”). High doses of zinc is characterized by vomiting, headaches, diarrhea, and exhaustion (Whitney & Rolfes, 2013). Supplementation of any mineral can lead to imbalances, but zinc supplements have proven very useful for certain circumstances, especially in developing countries. The supplements contribute to a decrease in the prevalence of disease, as well as death, related to diarrhea in children. Also, zinc supplements in the form of lozenges have been used to treat the common cold. Some studies have had conflicting results, but it is accepted that zinc is a beneficial temporary fix for a sore throat (“Zinc Fact”).

References

Whitney, E. N., & Rolfes, S. R. (2013). Understanding nutrition (13th ed.). Belmont, CA: Thomson/Wadsworth.

Zinc. (n.d.). Retrieved December 1, 2015, from http://www.aoa.org/patients-and-public/caring-for-your-vision/diet-and-nutrition/zinc?sso=y

Zinc Fact Sheet for Health Professionals. (n.d.). Retrieved December 1, 2015, from https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/