Role of Zinc in Linear Growth

By - Danone Nutricia Academy

Good nutrition in terms of quality and quantity in the first two years of life is particularly important due to its role in promoting normal mental and physical development.¹

Inappropriate feeding practices increase the risk of child malnutrition like stunting, wasting, underweight, overweight or obesity^1,2 .As per the global nutrition report 2020, 1 in 3 Indian children are stunted ³ and consequently are at an increased risk of adverse health consequences throughout life.

Role of zinc in growth ⁴

Zinc plays a critical role in growth and has an action on more than 300 enzymes by participating in their structure or their catalytic and regulatory actions.

DNA and RNA synthesis: Zinc participates in DNA and RNA synthesis, through the concept of zinc fingers in cell replication; differentiation of chondrocytes, osteoblasts, and fibroblasts; cell transcription; and synthesis of somatomedin-c, collagen, osteocalcin, and alkaline phosphatase

Hormone Mediation: Zinc also interacts with important hormones involved in bone growth such as somatomedin-c, osteocalcin, testosterone, thyroid hormones, and insulin, and also enhances vitamin D effects on bone metabolism through the DNA synthesis stimulation that happens in bone cells.

Reduces risk of infection: Zinc supplementation helps to boost immunity, prevent and palliate diarrhea and pneumonia. ⁵

Smell, taste and appetite regulation: Zinc also alters appetite control by acting directly on the central nervous system, altering the responsiveness of receptors to neurotransmitters.

Effects of Zinc deficiency

Zinc deficiency is accompanied by alterations in smell and taste, anorexia, weight loss, growth retardation, decreased resistance to infections, impaired immune function which contribute significantly to morbidity and mortality in young children. Although severe zinc deficiency is rarely found in humans, mild to moderate deficiency may be common which is difficult to diagnose, as signs and symptoms like increased susceptibility to infections and growth retardation are shared with other nutrient deficiencies and childhood illnesses ^4,5. The major causes of zinc deficiency in infants may include unbalanced meals, lower absorption ability in the intestinal tract, and low zinc concentration in maternal breast milk .⁶

Daily Zinc requirement during childhood

Daily adequate intake of zinc is important because there is no storage system for zinc in the body ⁷ . Breast milk zinc content varies depending on the duration of lactation.⁶

Recommended Dietary Allowance ⁸

Age

RDA

(mg/day)

6-12 months

2.5

1-3 years

Animal foods are particularly high in zinc however zinc can be obtained from vegetarian sources like beans, nuts, whole grains, and dairy products also contain zinc. However, vegetarian sources also contain phytates which bind zinc and can inhibit its absorption, thus reducing the bioavailability of zinc⁹ .

Bening S et al., 2017 found that low adequacy level for zinc is the most influential factor for stunting incidence in children aged 2-5 years ¹⁰ . However recently there is much evidence that zinc supplementation helps in linear growth in infants. Abdollahi M et al(2019),conducted a trial that evaluated the effect ofzinc supplementation (zinc sulfate 5ml for 6 months) in infant development in children aged 6–24 months (n = 682, intervention n = 272, control n = 308) and observed that intervention group, compared with the placebo group, had a significant difference in the average length increment (placebo 5⋅23 ± 2⋅19 vs. intervention 5⋅79 ± 2⋅18 cm, p = 0⋅02)¹¹
Zinc deficiency in children may impact growth and development. Therefore it is very important to provide a diet which provides adequate amount zinc and prevents zinc deficiency.

References:

Infant nutrition Available from: https://www.who.int/health-topics/infant-nutrition#tab=tab_1
Malnutrion Available from: https://www.who.int/news-room/q-a detail/malnutrition#:~:text=Malnutrition%20refers%20to%20
deficiencies%2C%20excesses,2%20broad%20groups%20of%20conditions.
Global Nutrition Report 2020. Available fromhttps://globalnutritionreport.org/resources/nutrition-profiles/asia/southern-asia/india/
Salgueiro, M., Zubillaga, M., Lysionek, A., Caro, R., Weill, R., &Boccio, J. (2002). The role of zinc in the growth and development of children. Nutrition, 18(6), 510-519. doi: 10.1016/s0899-9007(01)00812-7
E. Caulfield, L., A. Richard, S., A. Rivera, J., Musgrove, P., & E. Black, R. (2006). Stunting, Wasting and Micronutrient deficiency Disorders(2nd ed.). Washington (DC): The International Bank for Reconstruction and Development / 2) The World Bank.
Yasuda, H., &Tsutsui, T. (2016). Infants and elderlies are susceptible to zinc deficiency. Scientific Reports, 6(1). doi: 10.1038/srep21850
Infant nutrition and feeding: A guide for use in the special supplemental nutrition program for women, infants and children (2019). U.S. Department of Agriculture, Food and nutrition service, FNS – 826.
Recommended dietary allowances and estimated average requirements nutrient requirements for Indians – 2020, ICMR-National Institute of Nutrition.
Zinc Available from: https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
Bening, S., Margawati, A., &Rosidi, A. (2017). Zinc deficiency as risk factor for stunting among children aged 2-5 years. UniversaMedicina, 36(1), 11.
Abdollahi, M., Ajami, M., Abdollahi, Z., Kalantari, N., Houshiarrad, A., &Fozouni, F. et al. (2019). Zinc supplementation is an effective and feasible strategy to prevent growth retardation in 6 to 24 month children: A pragmatic double blind, randomized trial. Heliyon, 5(11), e02581. doi: 10.1016/j.heliyon.2019.e02581