Zinc
What is Zinc?
Zinc is a trace mineral involved in hundreds of important processes in the body including metabolizing nutrients, immune system support, and the health of body tissues and wound healing. Daily intake of zinc is important because it cannot be stored in the human body.
Low levels of zinc can affect your taste and smell, which can cause lack of appetite or potentially increase picky eating.
Zinc deficiency can present as pica, or the craving of non-food items such as dirt, clay, sand, or ice chips. [1]
Dietary zinc and zinc supplementation has been identified to have a therapeutic effect for individuals with ASD, and low levels may have an association with increased autistic behavioral symptoms. [2-4, 6-7]
Recommended Intake
These recommendations are based off of the Recommended Dietary Allowance (RDA), which is the average daily level of intake sufficient to meet the nutrient recommendations of nearly all (97-98%) of healthy individuals.
Males
1-3 years: 3 mg
4-8 years: 5 mg
9-13 years: 8 mg
14+ years: 11 mg
19-50 years: 3 mg
51+ years: 3 mg
Females
1-3 years: 3 mg
4-8 years: 5 mg
9-13 years: 8 mg
14-18 years: 9 mg
19+ years: 8 mg
Deficiency
Signs of Zinc Deficiency Include:
Stunted growth
Loss of appetite
Impaired immune function
Hair loss
Diarrhea
Eye and skin lesions
Weight loss
Delayed healing of wounds
Taste and smell abnormalities
Mental lethargy
Zinc deficiency is hard to test for due to its many uses throughout the body. A plasma or serum zinc level test can be done, but it can be inaccurate. The best way to determine a zinc deficiency is a clinical assessment along with intracellular testing.
Individuals at risk
Individuals with restrictive diets
GI issues including surgeries or disorders (ulcerative colitis/Crohn’s disease)
Other medical issues like chronic liver disease, chronic kidney disease, diabetes, or chronic diarrhea.
Vegetarians or vegans
Alcohol dependency
Pregnant and lactating women
Toxicity
Zinc toxicity symptoms can occur suddenly from an event such as taking too much of a zinc supplement at one time or if taken chronically at a higher level than recommended. Toxicity is more frequently reached when supplements are involved, versus consuming high amounts of foods that contain zinc.
Single Event Toxicity Symptoms
Nausea
Vomiting
Loss of appetite
Abdominal cramps
Diarrhea
Headaches
Chronic Toxicity Symptoms
Low copper levels
Altered iron function
Reduced immune function
Low HDL Cholesterol
The Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.
Males & Females
1-3 years: 7 mg
4-8 years: 12 mg
9-13 years: 23 mg
14-18 years: 34 mg
19-50 years: 40 mg
Supplements
Zinc can be found in two forms for supplementation which includes zinc sulfate and zinc acetate. Research has not been able to say whether one form is better in any way than the other.
Examples
Note: All supplements are linked to Amazon for convenience, however, buying supplements on Amazon does not guarantee quality, as there are many “unverified resellers” selling nutrition supplements. To buy supplements that are verified to be sent directly to the consumer, you can create an account on the Autism Dietitian FullScript and search for the respective supplement under “Catalog”.
DISCLAIMER: Before starting any supplement or medication, always consult with your healthcare provider to ensure it is a good fit for your child. Dosage can vary based on age, weight, gender, and current diet.
Zinc & Autism in the Research
Low Zinc Levels
Zinc Supplementation
Dietary zinc and zinc supplementation has been identified to have a therapeutic effect for individuals with ASD. [2-4]
Maternal Zinc Levels
Abnormalities of zinc levels in the mother during pregnancy may lead to impairments in brain function later in life for the offspring. Maternal zinc deficiency could cause systemic inflammatory events and prenatal stress that has been reported to increase risk of autism in the offspring. [5]
Zinc Levels & Autism Severity
There are links between zinc levels found in the hair of autistic children decreasing as the child gets older. The lower the zinc levels within the hair then have an association with increased autistic behavioral symptoms such as defective functional play and creativity and increase of stereotyped behavior. [6]
Hair levels of calcium, iron, iodine, magnesium, manganese, molybdenum, zinc, and selenium were considered deficient. There was a significant negative correlation between zinc & fear and nervousness (meaning that the lower the zinc levels, the more fear and nervousness). [7]
SHANK3 + Phelan McDermid Syndrome
SHANK3 is a leading autism candidate gene, with mutations occurring in between 1 and 2 percent of individuals with autism spectrum disorders. SHANK3 encodes a protein that is essential for proper functioning of the synapse, the junction between neurons. SHANK3 has been shown to correlate with zinc deficiency and autism. [8-10]
Phelan McDermid Syndrome (PMDS) is a rare type of autism spectrum disorder. PMDS is caused by a heterozygous deletion of the 22q13.3 region including SHANK3. SHANK3 is a neurological protein with mutations often found in individuals with ASD. This study investigated whether the observed increased incidence rate of Zn deficiency in ASD also occurs in PMDS, a disorder with a clear genetic cause. A high incidence rate of Zn deficiency was found in PMDS patients by analyzing hair samples. [10]
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[1] Miao D, Young SL, Golden CD. A meta-analysis of pica and micronutrient status. Am J Hum Biol. 2015;27(1):84-93.
[2] Fourie C, Vyas Y, Lee K, Jung Y, Garner CC, Montgomery JM. Dietary Zinc Supplementation Prevents Autism Related Behaviors and Striatal Synaptic Dysfunction in Exon 13-16 Mutant Mice. Front Cell Neurosci. 2018;12:374.
[3] Curtin P, Austin C, Curtin A, et al. Dynamical features in fetal and postnatal zinc-copper metabolic cycles predict the emergence of autism spectrum disorder. Sci Adv. 2018;4(5):eaat1293.
[4] Meguid, N.A., Bjørklund, G., Gebril, O.H. et al. The role of zinc supplementation on the metallothionein system in children with autism spectrum disorder. Acta Neurol Belg 119, 577–583 (2019). https://doi.org/10.1007/s13760-019-01181-9
[5] Vela G, Stark P, Socha M, Sauer AK, Hagmeyer S, Grabrucker AM. Zinc in gut-brain interaction in autism and neurological disorders. Neural Plast. 2015;2015:972791.
[6] Fiore M, Barone R, Copat C, et al. Metal and essential element levels in hair and association with autism severity. J Trace Elem Med Biol. 2020;57:126409.
[7] Blaurock-busch E, Amin OR, Dessoki HH, Rabah T. Toxic Metals and Essential Elements in Hair and Severity of Symptoms among Children with Autism. Maedica (Buchar). 2012;7(1):38-48.
[8] Schoen M, Asoglu H, Bauer HF, et al. Transgenic and Prenatal Zinc-Deficient Autism Mouse Models Show Convergent and Individual Alterations of Brain Structures in MRI. Front Neural Circuits. 2019;13:6.
[9] Hagmeyer S, Sauer AK, Grabrucker AM. Prospects of Zinc Supplementation in Autism Spectrum Disorders and Shankopathies Such as Phelan McDermid Syndrome. Front Synaptic Neurosci. 2018;10:11.
[10] Pfaender S, Sauer AK, Hagmeyer S, et al. Zinc deficiency and low enterocyte zinc transporter expression in human patients with autism related mutations in SHANK3. Sci Rep. 2017;7:45190.
