Dr. K here. Zinc is one of my most-used supplements in my practice, both for pediatrics and adult patients. I use zinc most often for diarrhea, picky eating, eczema, general immune support, and anxiety in children. (Of course, this is all very patient-specific, and depending on the overall need/s of the child.) Though true zinc deficiency is rare in developed countries, functional zinc deficiency is quite common, especially in patients with impaired absorption or in times of increased need (e.g., growing children). Zinc lozenges are tasty and compliance tends to be good. Personally, I like Seeking Health or Douglas Labs zinc lozenges. Do be aware that over-supplementation with zinc can cause a copper deficiency. Patients who are dosed with zinc above the daily Tolerable Upper Intake should also take low-dose copper, OR should have their serum copper levels monitored for signs of deficiency. To be on the safe side I often have children take supplement breaks periodically (e.g., over the summer).
What is zinc and what is it used for in the body?
Zinc is the second most abundant trace mineral in the body following iron. It acts as a cofactor for more than 100 different enzymes, making it an important player in a variety of reactions throughout multiple body systems.1 Zinc plays a critical role in everything from protein folding, regulating gene expression, RNA and DNA synthesis, cell proliferation and differentiation, stabilizing cell structures and membranes, to apoptosis.2
The most well known role of zinc is in enhancing immunity. It does so by regulating intracellular signaling pathways in both innate and adaptive immune cells. Due to its role in immunity, deficiencies are associated with infectious diseases like HIV, tuberculosis, measles, and pneumonia. Zinc is important throughout every phase of life, and is particularly important in supporting immune health, growth, cognitive development, and gut health in children.2
How much zinc should children have?
The Recommended Dietary Allowance (RDA) for children is as follows:
- 0–6 months: 2 mg
- 7–12 months: 3 mg
- 1–3 years: 3 mg
- 4–8 years: 5 mg
- 9–13 years: 8 mg
- 14–18 years: 11 mg (male); 9 mg (female).
It’s important to remember that the RDA is set to prevent deficiency, not to optimize health. Children may need more or less than the listed amounts depending on a variety of factors such as growth rate and their willingness to eat zinc-containing foods. Frank zinc deficiencies are rather uncommon in developed countries, although insufficient intake is very common. A mild zinc deficiency can be treated with approximately 2-3 times the RDA, while a more moderate or severe deficiency may require 4-5 times the RDA. Multiple types of zinc supplements are commonly used, including zinc acetate, zinc gluconate, zinc picolinate, zinc sulfate, and zinc oxide.1
How much zinc is too much?
The Tolerable Upper Limit for supplementation is as follows:
- 0-6 months: 4 mg
- 7-12 months: 5 mg
- 1-3 years: 7 mg
- 4-8 years: 12 mg
- 9-13 years: 23 mg
- 14-18 years: 34 mg
Food Sources of Zinc:
The body’s ability to absorb zinc depends on the zinc status of the individual, the content of zinc in the diet, and the availability of soluble zinc from the diet.3 Zinc absorption and retention is typically upregulated in individuals with low zinc status.
Zinc absorption is inhibited by several dietary factors like phytic acid, calcium, and iron.3 Phytic acid is found in plant seeds like grains and legumes. Soaking or fermenting grains and legumes can help reduce the content of phytic acid, thereby minimizing the inhibition of zinc absorption. However, this is one of the primary reasons zinc is more bioavailable from animal sources than plant sources. Furthermore, calcium, iron, and zinc all share a transporter. Therefore, if one of these minerals is being consumed in large amounts, the transport of the others decreases. For example, children who drink a lot of cow’s milk may inadvertently inhibit zinc absorption.
The most bioavailable sources of zinc come from animal products like oysters, beef, crab, lobster, pork, chicken, and yogurt. The phytic acid content of plant foods makes the zinc more challenging to absorb, but plant foods like beans, pumpkin seeds, cashews, and chickpeas contain smaller amounts of zinc.4
Unfortunately, many of the richest sources of zinc come from foods that may be unappealing to children (i.e. oysters). Rotating a variety of high quality animal products through your child’s diet is a good way to increase their exposure and ultimately the odds they discover a zinc-rich food they enjoy.
How can I tell if my child is zinc deficient?
Assessing for zinc is rather difficult and thus the signs and symptoms are often used to determine a deficiency. Some symptoms of zinc deficiency include delayed growth or puberty, diarrhea, alopecia, glossitis, white spots on the nails, and frequent illness.1
Various inflammatory diseases like Crohn’s disease, celiac disease, and sickle cell disease can impair absorption of the nutrient and lead to a deficiency.1 Other circumstances like pregnancy, lactation, or intravenous feeding over long periods of time increase the need for zinc, while vegan or vegetarian diets, short bowel syndrome, or gastric bypass may result in a deficiency due to decreased intake or absorption.
Children are at an increased risk of deficiency due to the increased requirements during growth.1 The highest physiological requirement for zinc peaks during children’s growth spurts, typically around 10 to 15 years in girls and 12 to 15 years in boys.3 Once the growth spurt has stopped, they may continue to require additional zinc in order to replete their diminished tissue zinc pools3.
Even marginal zinc deficiency can cause impaired immunity, increase oxidative stress and inflammatory cytokines, and delay wound healing.2 In children, a zinc deficiency may present as slowed cognition, trouble focusing and remaining alert, impaired appetite, diarrhea, depressed immune function, and chronic respiratory infections.1 Other indications that a child may not be consuming enough zinc include poor sense of taste and smell, slowed growth, and wounds that take a long time to heal.
What are the signs of too much zinc?
Signs of zinc excess are usually limited to the gastrointestinal tract. Some signs include metallic taste, nausea, vomiting, cramping, and diarrhea. Excessive intake over long periods of time may lead to suppression of the immune system, a decrease in HDL cholesterol, and copper deficiency.1
Zinc is useful in children with diarrhea at doses of 5-20 mg.1 Consistent administration of doses larger than this amount may exacerbate the child’s GI symptoms and could lead to a depressed immune system and/or copper deficiency.
Is zinc safe for kids?
Zinc supplementation up to the tolerable upper intake level is generally considered safe. High doses are sometimes used in children with moderate to severe deficiencies or in acute cases of diarrhea. In these instances, the high doses should be limited to a short period of time (10-14 days) in order to prevent gastrointestinal distress, copper deficiency, anemia, or genitourinary complications.1
What do naturopathic doctors use zinc for?
Research suggests that zinc deficiencies may be an accelerating factor in the pathology of anorexia by impacting food intake regulation.4 Animal studies, particularly those done on rats, show that young rats fed a zinc-deficient diet begin displaying reduced food intake within 3 to 5 days, much earlier than other signs of zinc deficiency appear.4 Although the relationship between zinc deficiency and anorexia behaviors is strong in animal studies, the evidence is less clear in human trials. However, clinical studies show that approximately half of all patients with Anorexia Nervosa (AN) are zinc deficient. In one study, 14 mg of zinc gluconate was found to double the rate of body mass increase in patients with AN when compared to a placebo.4 It is important to note that AN can cause numerous nutrient deficiencies, often including thiamin which may lead to similar anorexia behaviors.
Children with picky eating behaviors are at a significantly increased risk of zinc deficiency. Low zinc is associated with a reduced sense of taste and smell. Zinc is also required for the production of stomach acid. Without adequate stomach acid, protein becomes difficult to digest and may leave the child feeling full after even small amounts of food. The combination of poor taste and smell, impaired digestion, and the appetite suppression caused by a zinc deficiency likely leads to more significant picky eating behaviors. Unfortunately, zinc deficiency is correlated with poor development and decreased physical activity in young children.5 A low dose zinc supplement of about 15 mg/d can be leveraged in children with picky eating. Clinically I have seen good success with improving (but not completely resolving) picky eating behaviors by supplementing low-dose zinc.
Recent studies are beginning to connect zinc deficiency and mood disorders like anxiety attacks, depression, OCD, and even PTSD. Zinc deficiency is associated with depressive symptoms that improve following supplementation. Zinc is present in the glutamatergic neurons in areas of the brain known to be involved in emotion, learning, and memory. Zinc may act as a neuromodulator between glutamate and GABA because of its location and thus plays a critical role in modulating excitatory and inhibitory neurotransmission. Furthermore, zinc activates hormonal, neurotransmitter, and signaling pathways in the gut which influence certain brain functions like sleep, appetite, neurogenesis, cognition, and mood. Disruptions to any of these brain functions are closely associated with mood disorders.6 For more information I recommend reading The Role of Zinc in Mood Disorders in the Journal of Neuropsychiatry.
Perhaps one of the most well known applications of zinc is in treating diarrhea episodes in children. Zinc supplementation during diarrhea episodes has been shown to reduce the duration, severity, and risk of recurrence within the following two to three months.7 The World Health Organization recommends 20 mg of zinc a day for 10 to 14 days for children with acute diarrhea, and 10 mg per day for infants under six months of age. Zinc sulfate, acetate, and gluconate have all been proven effective.
Irritable Bowel Syndrome (IBS) affects approximately 12% of the population. Zinc deficiency may perpetuate the underlying pathophysiology due to its role in the gut-brain axis, the immune system, and the integrity of the gastrointestinal lining. One study found that people with IBS had significantly higher ratios of copper to zinc, indicating a zinc deficiency. Zinc also plays a role in the production of stomach acid. Hypochlorhydria (low stomach acid) can lead to IBS symptoms such as bloating, a sense of fullness, gas, undigested food in stool, and diarrhea. Given zinc’s role in the immune system, GI barrier, gut-brain axis, and stomach acid production, a deficiency may perpetuate the underlying pathophysiology of IBS.13
Zinc plays an important role in maintaining the integrity of the skin and healing wounds. It has been successfully used as a topical agent for various skin issues such as acne, warts, dandruff, rosacea, keloids, and vitiligo. Topical zinc may be an effective treatment for atopic dermatitis (eczema) due to its strong antioxidant and antibacterial action. It has also been shown to improve diaper dermatitis.8 The benefits of topical zinc come from its anti-inflammatory and re-epithelialization properties.
Zinc is an essential nutrient for brain development. Deficiencies during gestation can lead to fetal brain malformations and have long term ramifications on the nervous system.9 Zinc deficiency during gestation impacts neurogenesis, neuronal migration, differentiation, and apoptosis, all of which significantly impact brain health and may increase the risk of behavioral and neurological disorders in the offspring9. Low maternal intake is associated with less focused attention in neonates and decreased motor functions in infants.10
In low birth weight infants, zinc supplementation has been shown to improve motor development and playfulness.10 However, the research remains inconclusive on the effect of zinc supplementation in school aged children. It seems that zinc supplementation is most effective in more vulnerable populations such as low birth weight infants or malnourished children.11 That being said, a well rounded and balanced diet is essential for proper cognitive development in children of all ages.
Zinc deficiency is known to limit linear growth, weight gain, and lean body mass accretion in children, likely due to the reduction in insulin-like growth factor that occurs as a result of zinc deficiency.9 In one study, children under two years of age who had stunted growth yielded catch-up growth and increased insulin-like growth factor following zinc supplementation. A review of the evidence found that zinc supplementation improved specific growth outcomes like height, weight, and weight for age. This correlation is strongest in children between the ages of two and five and the effects are most pronounced in children with suboptimal zinc status.12 The evidence suggests that zinc supplementation may not be warranted for all children, but vulnerable children such as low birth weight infants or those with suboptimal zinc may see improvements in cognition and physical growth.
Upper Respiratory Tract Infection prevention (preventing colds)
Zinc is moderately effective in preventing viral replication in many cases.14 One meta-analysis showed that oral zinc may reduce the duration of the common cold. However, zinc must be in an ionized form and must be given in relatively high doses. Timing is also extremely important. Remember that viral replication occurs very early in the illness, often before symptoms even develop. Zinc will be entirely ineffective when given too late. After 24 hours of illness it is likely that zinc will be ineffective. Zinc acetate or gluconate lozenges have the best evidence currently, though it is possible that other forms of zinc may be effective as well. Lozenges allow the zinc to linger on the mucus membranes, providing direct antiviral activity. Swallowed capsules are less effective for URI prevention. Zinc sprays are also likely effective against viruses, but side effects may include permanent loss of smell. For this reason nasal sprays are not recommended. 14
In short, zinc is an essential mineral for hundreds of processes in numerous body systems. Children are at an increased risk of deficiency due to their rapid growth. Adequate intake of zinc-rich foods such as oysters, beef, chicken, legumes, and seeds ensures proper immune health, growth, cognitive development, skin and gut health in children. Specific conditions such as acute diarrhea episodes, eczema, picky eating, and even mood disorders may benefit from targeted zinc supplementation.
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- Saper RB, Rash R. Zinc: An Essential Micronutrient. Am Fam Physician. 2009;79(9):768-772.
- Maywald M, Wessels I, Rink L. Zinc Signals and Immunity. Int J Mol Sci. 2017;18(10):2222. Published 2017 Oct 24. doi:10.3390/ijms18102222
- Roohani N, Hurrell R, Kelishadi R, Schulin R. Zinc and its importance for human health: An integrative review. J Res Med Sci. 2013;18(2):144-157.
- Neil F. Shay, Heather F. Mangian, Neurobiology of Zinc-Influenced Eating Behavior, The Journal of Nutrition, Volume 130, Issue 5, May 2000, Pages 1493S–1499S, https://doi.org/10.1093/jn/130.5.1493S
- Chao HC, Lu JJ, Yang CY, Yeh PJ, Chu SM. Serum Trace Element Levels and Their Correlation with Picky Eating Behavior, Development, and Physical Activity in Early Childhood. Nutrients. 2021;13(7):2295. Published 2021 Jul 2. doi:10.3390/nu13072295
- Piao M, Cong X, Lu Y, Feng C, Ge P. The Role of Zinc in Mood Disorders. Neuropsychiatry. 2017;7:4.
- Bajait C, Thawani V. Role of zinc in pediatric diarrhea. Indian J Pharmacol. 2011;43(3):232-235. doi:10.4103/0253-7613.81495
- Gupta M, Mahajan VK, Mehta KS, Chauhan PS. Zinc therapy in dermatology: a review. Dermatol Res Pract. 2014;2014:709152. doi:10.1155/2014/709152
- Brion, L.P., Heyne, R. & Lair, C.S. Role of zinc in neonatal growth and brain growth: review and scoping review. Pediatr Res 89, 1627–1640 (2021). https://doi.org/10.1038/s41390-020-01181-z
- Bhatnagar S, Taneja S. Zinc and cognitive development. Br J Nutr. 2001;85 Suppl 2:S139-S145. doi:10.1079/bjn2000306
- Black MM. The evidence linking zinc deficiency with children’s cognitive and motor functioning. J Nutr. 2003;133(5 Suppl 1):1473S-6S. doi:10.1093/jn/133.5.1473S
- Liu E, Pimpin L, Shulkin M, et al. Effect of Zinc Supplementation on Growth Outcomes in Children under 5 Years of Age. Nutrients. 2018;10(3):377. Published 2018 Mar 20. doi:10.3390/nu10030377
- Hujoel IA. Nutritional status in irritable bowel syndrome: A North American population-based study. JGH Open. 2020;4(4):656-662. Published 2020 Feb 12. doi:10.1002/jgh3.12311
- Science M, Johnstone J, Roth DE, Guyatt G, Loeb M. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ. 2012 Jul 10;184(10):E551-61. doi: 10.1503/cmaj.111990. Epub 2012 May 7. PMID: 22566526; PMCID: PMC3394849.