Introduction
Zinc is a chemical element, a micronutrient vital to life, and is one of the most widely used metals. Zinc is of considerable commercial and health-related significance. It is an essential and irreplaceable trace element in the human body, which helps cure and prevent some diseases. However, the issue of choosing a perfect dosage of this micronutrient depending on different conditions is more complex than it seems.
The Impact on an Organism
Irreplaceable for the human body, zinc has some specific characteristics. Zinc’s atomic symbol is Zn, atomic number is 30, and atomic weight is 65.39 (NCIT, n.d.). According to Wojtunik-Kulesza et al., zinc is substantial because it is a significant component of such enzymes as “phospholipase C, alcohol dehydrogenase, carbonic anhydrase, Zn-Cu superoxide dismutase, carboxypeptidase,” more than 300 total (2019, p. 1284). Blood pressure as a heart-related process depends on the concentration of zinc and the protein synthesis in the body; hence muscle growth is not possible without zinc (Wojtunik-Kulesza et al., 2019). In addition, the part of zinc in the removal of heavy metals from the body cannot be left unnoticed.
There are particular organs, tissues, and liquids in the human body where minor amounts of zinc can be stored. High zinc concentrations can be found in the erythrocytes as a substantial part of the enzyme carbonic anhydrase. They provide the maintenance of many reactions connected to carbon dioxide metabolism (Britannica, 2020). Zinc is a component of enzymes digesting protein in the gastrointestinal tract, contributing to insulin storage in the pancreas, and more (Britannica, 2020). Thus, it influences various processes in the body and has an impact on its general condition.
No doubt, there are more effects of zinc, including positive and negative ones. For instance, it has exceptional qualities related to boosting the immunity system and healing wounds and is involved in numerous processes of cellular metabolism (NIH, n.d.). The catalytic activity of more than a hundred enzymes is drastically affected by zinc, which in addition contributes to “immune function, protein synthesis, DNA synthesis, and cell division” (NIH, n.d.). What is more, healthy pregnancy requires maintaining an appropriate zinc concentration in the body’s tissues and organs. Also, people would not feel taste and smell without zinc because they would not have these senses (NIH, n.d.). This micronutrient is of extreme importance for maintaining the healthy condition of an organism.
Sources of Zinc
Due to the fact that the human body does not have any systems for zinc storage, people should get the appropriate amount of this micronutrient daily. Many foods contain zinc, with high levels found in beef, shellfish, spinach, beans, legumes, nuts, seeds, and whole grains (NIH, n.d.). Interestingly, more zinc is served in oysters than in any other dish (Saito et al., 2017). In addition to the sources of zinc mentioned above, it is also contained in “certain types of seafood, such as crab and lobster, and dairy products” (NIH, n.d.). Moreover, pork is rich in zinc and can provide the needed amount for the human body (Harvard School of Public Health, n.d.). The range of zinc products is vast, so it is already included in even intuitively healthy diets.
However, some issues may intervene the zinc absorption and affect the concentration of the element in the human body. For example, recent studies have shown that following a not nutritious enough diet and eating large amounts of phytates found in nuts, grains, cereals, and other plants, can cause problems with zinc absorption (NIH, n.d.). In this regard, a 2009 study revealed that vegetarians might be at risk for zinc deficiency (NIH, n.d.). The blood zinc levels of vegetarians in the study were low due to the high intake of phytates in their diet. Thus, choosing a vegetarian diet should always be based on a nutritionist’s decision.
Dietary Supplements
As it may be challenging to get the required concentration using the food sources only, dietary supplements contain this mineral. Zinc concentration in supplements differs drastically and can be explained by the aim of intaking each of them – the disease predetermines the dose. Such variation is possible because no differences have been revealed concerning the element’s absorption concerning its form (Britannica, 2020). Thus, it can be used and applied differently depending on the form of its content.
Toxicity
Although zinc is not naturally toxic and is considered to bring benefits to living organisms, it can be toxic if it is dosed incorrectly. Zinc supplements are far more likely to lead to the appearance of this negative side if intaking zinc in comparison with food sources because of the element’s concentration. Signs of toxicity may include nausea and vomiting, poor appetite, abdominal pain or cramping, headaches, and diarrhea (Harvard School of Public Health, n.d.). Zinc is contained in denture adhesive creams, leading to neurological diseases and copper deficiency if used too frequently, and the concentrations exceed the appropriate values (NIH, n.d.). Therefore, in some cases, zinc can become toxic if it is misused or used in higher concentrations than required.
Zinc Deficiency: Overview
Due to the importance of zinc for the organism, its deficiency leads to severe consequences. Zinc deficiency can be associated with a wide range of symptoms, including “weight loss, delayed healing of wounds, and taste abnormalities” (Harvard School of Public Health, n.d.). Other probable effects of this micronutrient deficiency are “delayed sexual maturation, hair loss, hypogonadism in males, diarrhea, impotence, and eye and skin lesions” (NIH, n.d.). Considering the lack of zinc, the human body may face “growth retardation, loss of appetite, taste or smell, mental lethargy, and impaired immune function” (Wessels & Rink, 2019). According to this list of possible consequences of the lack of zinc, it affects most of a body’s vital systems and maintains its coherent work.
Autoimmune Diseases
All cells require zinc and need to maintain balanced intracellular zinc homeostasis to ensure proper function. The balance is created by the cooperative action of 24 zinc transport proteins and several zinc-binding proteins such as metallothionein, albumin, transferrin, and calprotectin (Wessels & Rink, 2019). All cells suffer from zinc deficiency, but cells of the immune system are susceptible and strongly affected. Thus, the organism is at a considerably more potential risk of having autoimmune diseases. Wessels and Rink, in their study, have proved that the concentration of zinc in plasma and serum there was “lower… in autoimmune patients compared to healthy controls” (2019). As far as this fact is concerned, zinc deficiency can affect the ability of an organism to confront all the existing diseases; thus, it can be referred to as a cause of them.
Brain Diseases
Considering brain diseases, which development the zinc deficiency stimulates, there are several of them. Firstly, the most common progressive dementia affecting the elderly, Alzheimer’s disease, is partly caused by zinc. If the concentration of the micronutrient is too high, it may result in the aggregation of amyloid-β into senile plaques, one of the major pathological hallmarks of the disease (Portbury & Adlard, 2017). What is more, the study has also revealed that “the synaptic release of zinc from presynaptic boutons can additionally cause injury and death to postsynaptic neurons under excitotoxic conditions” (Portbury & Adlard, 2017, p. 5). Both minor and large amounts of the micronutrient may have negative repercussions on the body and brain.
Another disease, amyotrophic lateral sclerosis, is a fatal neurodegenerative disease of the human motor system. The most common cause of this disease is a mutation to the copper, zinc superoxide dismutase gene (Portbury & Adlard, 2017). The mutation, which results in the superoxide dismutase gene, a protein having a reduced affinity for zinc, leads to a toxic gain of function in motor neurons when zinc is missing from its active site. Thus, the deficiency of zinc affects the brain and its regulatory functions strongly.
The variety of brain-related diseases is comprehensive, and zinc impacts the most severe ones, either providing us with the opportunity to prevent them or worsening the situation. In connection with Parkinson’s disease, a long-term degenerative disorder of the CNS that mainly affects the motor system, “there is an observed clinical zinc deficiency in patients presenting with PD” (Portbury & Adlard, 2017, p. 6). Irregularities in zinc homeostasis may represent a point of intersection for both the pathogenesis and the symptoms characterizing multiple neurodegenerative disorders, in addition to potentially being involved in the aging process and associated cognitive decline.
Zinc imbalance, which means either a low or a high amount of zinc that is not appropriate for the body, negatively affects its systems. The low level of zinc causes a wide range of diseases and even biological deviations, and nearly “50% of the global population” are under the influence of this fact (Wojtunik-Kulesza et al., 2019, p. 1285). The lack of zinc causes “oxidative stress, including lipid peroxidation, increased osmotic fragility of erythrocyte membranes, decreased protein turnover,” and other consequences with different levels of severity (Wojtunik-Kulesza et al., 2019, p. 1285). A slightly different situation is observed regarding the high absorption of zinc, which may bring the risks of negative alterations to human bodies.
According to the results of the studies on the topic, a high level of the element “leads to neuronal changes, which can contribute to the development of neurodegeneration” (Wojtunik-Kulesza et al., 2019, p. 1285). Such information on the overdose of zinc triggers the thought on a positive side of the fact that it cannot be stored and accumulated, so the human body saves itself by automatically reducing any zinc concentration excesses. This way, controlling the amount of zinc present in the body is much easier because it depends primarily on the amount of this micronutrient a person consumes.
Psychological Effects: Depression
In addition to numerous severe diseases affecting the body and brain, zinc imbalances may also lead to psychological problems. Zinc level and depression were first proved to have an interrelation more than three decades ago. Since then, it has been studied in humans and animals. Zinc imbalances in rodents’ bodies were traced in connection with the symptoms of depression, and their correlation was revealed (Wang et al., 2018). Another study was held among a group of people, in which “female adolescents, postmenopausal women, and patients on hemodialysis” have shown the same results (Wang et al., 2018, p. 2), while the same study on men has not reflected any connections between depression and zinc deficiency. However, the mechanism of such influence of the micronutrient on the organisms of different sexes is not precise yet.
The interrelation of zinc level and the probability of depression is inverse, meaning that zinc has an effect close to antidepressant medicine. According to Wang et al., people with depression have shown fewer depression symptoms after adding supplements that contain zinc to their standard antidepressants (2018). Healthy young women were also distinguished into two groups for the study and were given multivitamin complexes with and without zinc. Those who got the microelement included in their diet demonstrated a more positive attitude towards life and better mood (Wang et al., 2018). According to the study undertaken by Wang et al., the mechanism that makes the interrelation of zinc and depression symptoms so strong may be connected to “the regulation of neurotransmitter, endocrine, and neurogenesis pathways” (2018, p. 2). Therefore, the effect of zinc imbalance can be considered similar for animals and human beings, as it touches on the same chemical and biological processes.
Sleep Efficiency
Generally, it is hard to reveal zinc deficiency because there are almost no symptoms for a long time, and they are not particular for this microelement. Zinc improves sleep when ingested for the long-term in meals daily (Saito et al., 2017). Results of the study by Saito et al. have revealed that people with low zinc concentrations in their diets sleep have a poor quality of sleep (2017). At the same time, those whose daily intake of zinc is enough sleep well and have generally better physiological indicators (Saito et al., 2017). What is more, according to Saito et al., people with lower zinc doses have a shorter sleep duration than people with average amounts of zinc (2017). It appeared that zinc concentrations exceeding normal levels negatively influence sleep duration (Saito et al., 2017). These facts only prove the importance of the micronutrient for organisms of different ages.
Doses
The dosages of zinc intake for ordinary people without medical prescriptions are regulated by the National Institutes of Health standards. The amounts primarily vary depending on the age and sex of the person. For instance, males aged 14 and older should 11 mg of zinc a day, while females aged 14 and older should get 9 mg (MNT, n.d.). In addition, pregnant women need to get 11 mg, and lactation women – 12 mg (MNT, n.d.). These amounts of zinc are beneficial for the listed above types of organisms and allow them to avoid various diseases discussed above.
Conclusion
To conclude, all the organic life on Earth requires a particular zinc concentration to live and function as it should. Zinc is vital to maintain the appropriate level of this microelement in the body by intaking it with food or medicine to stay healthy and prevent serious brain illnesses. However, both the lack and excess of zinc lead to negative consequences; therefore, pharmacists and doctors should control the individual dosage thoroughly.
References
Britannica, The Editors of Encyclopedia (2020). Zinc.
Harvard School of Public Health. (n.d.). Zinc.
Medical News Today. (n.d.). The top food high in zinc.
National Cancer Institute Thesaurus. (n.d.). Zinc.
National Institutes of Health. (n.d.) Zinc: Fact sheet for health professionals. National Institutes of Health.
Portbury, S. D., & Adlard, P. A. (2017). Zinc signal in brain diseases. International Journal of Molecular Sciences, 18, 1-13.
Saito, H., Cherasse, Y., Suzuki, R., Mitarai, M., Ueda, F., & Urade, Y. (2017). Zinc-rich oysters as well as zinc-yeast- and astaxanthin-enriched food improved sleep efficiency and sleep onset in a randomized controlled trial of healthy individuals. Molecular Nutrition & Food Research, 61(5).
Wang, J., Um, P., Dickerman, B. A., Liu, J. (2018). Zinc, magnesium, selenium and depression: A review of the evidence, potential mechanisms and implications. Nutrients, 10(5), 1-19.
Wessels, I., & Rink, L. (2019). Micronutrients in autoimmune diseases: Possible therapeutic benefits of zinc and vitamin D. The Journal of Nutritional Biochemistry, 77.
Wojtunik-Kulesza, K., Oniszczuk, A., & Waksmundzka-Hajnos, M. (2019). An attempt to elucidate the role of iron and zinc ions in development of Alzheimer’s and Parkinson’s diseases. Biomedicine & Pharmacotherapy, 111, 1277–1289.