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1.0 Introduction
Minerals has always been a part of a human’s life through food intake or
exposure without us even realizing it. Zinc is a very good example of a mineral that is
crucial to living organisms mainly humans and animals. Most rocks and other
minerals consists of zinc in varying amounts and it enters the air, water and soil due
to natural processes or activities done by humans.
Zinc is a bluish-silver element that is widely used in industries to make
cosmetics, ointments, lotions, weapons used in the army and many more. It is also
popular in manufacturing roofing materials or into chemical compounds such as zinc
oxide. This white powder is used in everything from sunscreen to solar cells to
nuclear reactors where its used to prevent corrosion. (Pappas.S,2015)
It is known that a range of 2-4 grams of zinc are present throughout the
human body (Wapnir R.,1990,Barceloux, 1999). Although this trace element is
mostly present in the brain, muscle, bones, kidney and liver, the highest
concentration of zinc is found in the prostate and parts of the eye (Osredkar, 2011).
Zinc is the second most abundant trace element that is found in the human body
apart from iron (Vasak ; Hasler,2000; Stefanidou, Maravelias, Dona, ; Spiliopoulou,
2006). Zinc is involved in most cell processes including DNA synthesis, normal
growth, brain development, behavioural response, reproduction, foetal development,
membrane stability, bone formation and wound healing. There are many benefits of
zinc in the human biological system such as to fight certain diseases but many are
still in the dark about the importance or effects one mineral can bring to oneself.
Good food sources of zinc include seafood, beef, lamb, eggs, whole grains,
nuts and yoghurt. Based on the list of food sources, we can conclude that the type of

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diet we follow affects the concentration of zinc that is present in our body whether it
is sufficient or the other way around. Being zinc deficient can influence brain activity,
immune system, male reproductive system, pregnancy and the speed of wound
healing. Excess of zinc on the other hand can cause some temporary effects but
some cases are more serious than others that can lead up to permanent damages.
This review describes the function of zinc, effects of high concentration of the
mineral, with focus on the significance of zinc in the human body in terms of immune
system, brain, skin, male reproductive system, pregnancy and pre-menstrual
syndrome.

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2.0 FUNCTION OF ZINC IN HUMAN BODY

There are 3 crucial roles involving zinc in human body such as catalytical,
structural and regulatory. Zinc plays a role as catalyst to 300 different kinds of
enzymes during their chemical reaction. Zinc is needed in catalysis and co-catalysis
by the enzymes which undergo many cell processes including DNA synthesis,
normal growth, brain development, behavioural response, reproduction, foetal
development, membrane stability, bone formation and wound healing (Barceloux,
1999; Mocchegiani, Muzzioli, ; Giacconi, 2000; Stefanidou et al., 2006). When zinc
is absent in their structure, it leads to an increase of oxidation and damages the
immune cell membrane and protein. This means that zinc is needed in structure of
protein and cell membrane. Zinc binds with metalloprotein,MTs and plays an
important role in the structural and functional of other proteins especially in DNA
replication and reverse transcription (Chasapis, Spiliopoulou, Loutsidou, ;
Stefanidou, 2012; Mocchegiani et al., 2000; Tapiero ; Tew, 2003). Zinc ions are
hydrophilic and cannot pass through cell membranes through passive diffusion.
Transportation of zinc related to saturation and unsaturation of components
depending on the amount of zinc. Gene sequence is regulated by zinc finger protein
which acts as transcription factors. In addition, zinc also encourages the release of
hormones and nerve impulse transmissions (Bhowmik ; Chiranjib, 2010). Enzymatic
activities are enhanced by zinc and also stabilizes the protein whereby the mineral
acts act as an activator or inhibitor ion (Chasapis et al., 2012; Mocchegiani et al.,
2000). Furthermore, zinc is also abundant in the forebrain which acts as a modulator
of synaptic neuron-transmission and modulator to cellular signal transduction
processes (Beyersmann, 2002;Stefanidou et al., 2006). Zinc homeostasis is

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important to regulate its absorption, distribution, cellular uptake and excretion.
(Vallee;Falchuk,993). Cytosol is where zinc is abundant followed by nucleus and
other part that is associated with membranes (Vallee;Falchuk,1993;Plum, Rink, ;
Hajo, 2010). The function of zinc homeostasis is used to prevent the accumulation of
zinc in excess. There are two protein families involve in zinc transportation which are
zinc importer. (zip;zrt-,Irt –like proteins) family and zinc transporter ( znT) family. Zinc
importer with 14 proteins is used to transport zinc into cytosol and zinc transporter
with 10 proteins transports zinc out of cytosol (Lichten ; Cousins, 2009; Plum et al.,
2010).

Figure 1: of role of zinc during cellular zinc homeostasis (Plum et al., 2010)

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3.0 Health benefits of zinc
A. Zinc in immune system
Immune system needs zinc essential trace element to fight against infections
due to viruses, bacteria, fungi and protozoa (Bonaventura et al., 2015). Zinc-binding
proteins, like metallothioneins (MTs) are from intra-cellular metal binding proteins
which are present in all living things and they are important for the zinc effect in the
immune system (Stefanidou et al., 2006). Without zinc, immune system cannot do
their work to ensure that the body is not exposed to any pathogen. It can decrease
lytic activity of natural killer cells, damage the natural killer T cell cytotoxicity and
immune signalling, affects the neuroendocrine immune pathway and alters cytokine
production in mast cells (Muzzioli et al.,2009; Mocchegianietal,2003; article 14).
Moreover, zinc is one of the components that is needed in thymic hormones which
commands and ease the process of lymphocyte maturation (Bhowmik ; Chiranjib,
2010). Basically, eating too little of zinc can impair the immune system making you
more likely to get sick.
Sometimes there are other factors to consider that can affect whether or not
Zinc requirements are met in the human body. These factors include diet consumed,
climatic conditions, and existence of stress due to stress, trauma, parasitic
infestations and infections (Stefanidou et al., 2006). When someone is sick with the
flu, it is said that the immune system is able to fight the flu virus with the aid of zinc.
People in contact with those who have viruses might get infected by them too. When
the body is exposed to pathogens, phagocytosis starts to trap and kill them by
producing reactive oxygen. This process usually occurs in innate immune system.
Low concentration of zinc is means by decrease in phagocytosis process

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(Bonaventura et al., 2015). Trace elements such as selenium, iron, copper, zinc and
copper to zinc ratios could serve as a symptom of viral liver failure (Kaur, Gupta,
Saraf, ; Saraf, 2014; Science ; Medical, 2006).
Innate immune system should begin first and then followed by an adaptive
immune system. Adaptive immune system is related to the T lymphocyte and B
lymphocyte. T lymphocyte is matured by thymulin with the aid of zinc. Thymulin is a
non-apeptidic hormone produced by thymic epithelial cell, (Dardenne, 2002). It was
known that after being deprived of zinc for too long, both human or animals are more
susceptible to injuries that comes with oxidative stress (Stefanidou et al., 2006).
Acrodermatitis enteropathica leads to zinc deficiency in humans and this is an
autosomal genetic recessive defect of the zinc metabolism which then affects
obstruction of zinc absorption (King, 2000).
Another reason to keep zinc levels in our body to be at a normal level is to
prevent creating damaged homeostasis in our system. This is due to the defective
platelet aggregation, a decrease in T-Cell number and the responsiveness of T-
lymphocytes to phytomitogens (Stefanidou et al., 2006). In terms of ageing, one of
the many roots causing immunological responses to decline is because
neuroendocrine function in the body system is failing (Mocchegiani et al., 2006;
Stefanidou et al., 2006) and increasing in apoptosis regulated by zinc (Stefanidou et
al., 2006).
The abnormal occurrence of various infections and the existence of
lymphopenia and lymphoid organ atrophy in malnourished children have been
observed many times. The evidence gathered had concluded that the reason is due

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to zinc insufficiency which is then related to this type of immunodeficiency
(Dardenne, 2002).
Much more diseases can be developed such as gastrointestinal disorders,
renal disease, sickle cell anaemia, alcoholism, some cancer types, AIDS, burns and
others (Fraker, King, Laakko, ; Vollmer, 2018; Keen, 1990; Mocchegiani ; Fabris,
1995; Stefanidou et al., 2006). Appropriate zinc supplementation prescribed to those
individuals could help in preventing damage towards their immune system and
massively improve the resistance of a host to fight against the infections (Dardenne,
2002).

B. Zinc in brain
i. Transportation of zinc from blood to brain
Zinc is an important nutrient for brain which is supplied through brain barrier
system that incorporates blood-brain and blood-cerebrospinal fluid barrier (Atsushi
Takeda, 2000). Blood brain barrier surface is greater than the surface of blood
cerebrospinal fluid barrier. Zinc homeostasis occur in brain barrier and its variation
may correspond to brain dysfunction and neurological diseases (A Takeda, 2001).
The brain is made up of limbic system which include the hippocampus, amygdalia
and zinc-containing glutaminergic neuron-rich areas. Hippocampus have high
concentration of zinc as grey matter(A Takeda, 2001). In contrast, brain stem,
cerebellum and spinal have low amount of zinc concentration (Koh, 2001). Zinc

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binding affinity for ligands takes place in serum as the serum categorized into 3
fractions which is protein-bound form, low molecular weight ligand-bound form and
free zinc ion. Zinc from blood must bind with protein such as histidine before they
transport to DMT1 (divalent metal transporter) or zinc transporter in brain. Albumin is
a massive component of exchangeable zinc and then followed by amino acid. Amino
acid consists of histidine and cysteine.
After zinc enters the brain side, they must pass through neuron and glial cell
before they transfer by zinc transporter such as DMT1. Neuron cell consist of two
sites for zinc to go through which are cell body and neuron terminal. In neuron, zinc
bind with protein to form zinc containing glutaminergic neurons which is taken up to
presynaptic vesicles. It is believed that presynaptic vesicles are concentrated in
hippocampal formation (Bush A.I et al, 1994;Atsushi Takeda, 2000). Zinc containing
glutaminergic neurons in presynaptic vesicles are used as neuromodulator which is
then transferred into postsynaptic vesicles by synaptic cleft. Synaptic cleft is located
between presynaptic vesicle and postsynaptic vesicle.

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Figure 2: Transportation of zinc from blood to neuron and glial cell (brainz)

Figure 3: Synaptic cleft in between presynaptic cell and postsynaptic cell
(http://www.zoology.ubc.ca/~gardner/synapses%20-%20presynaptic.htm)

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ii. Zinc Toxicity
Zinc hardly goes through redox activity compared to other metals (Bertholf
R.L et al, 1988; Atsushi Takeda, 2000). Excessive levels of zinc might be toxic to the
brain as it can cause damage to the cell membranes, change enzyme specificity,
disrupt cellular functions and destruct the structure of DNA. (Bruins et al.
2000;Daniels, Hendricks, Salie, ; Rensburg, 2004). Zinc toxicity occurs in
neurotransmitter system which contain glutaminergic neurons. Glutamate
transportation is modified by zinc that interrupt its removal in synaptic cleft which can
cause neuronal death (Daniels et al., 2004). As mentioned earlier, synaptic cleft is in
between presynaptic vesicle and postsynaptic vesicle. When presynaptic ending
receives an electrical signal, it is decoded into chemical messages. The synaptic
cleft receives the message and then send it to postsynaptic cleft.
Excessive amount of zinc can activate the formation of amyloid plaques in the
brain (Huang X et al,2000; Kaiser J,1994; Lee J.Y,1999;Atsushi Takeda, 2000).
Alzheimer’s disease is at risk if synapsis activity is in excess. (Frederickson,2005;
Nuttall & Oteiza, 2014). The accumulation of amyloid plaques usually found in
Alzheimer’s disease brain. Alzheimer’s disease usually starts slowly and worsen
over time. The major symptom is difficulty with language, easily getting lost, mood
swings, demotivated and not managing selfcare. Excess of zinc also retards the
amyloid precursor protein (APP) which diminishes the oxidation of iron that leads to
neuronal accumulation of ferrous iron (Nuttall & Oteiza, 2014). The ferrous iron can
increase the oxidative stress. In addition, neuronal cell death is the consequence of
the stimulation of kinases by zinc which promotes the accumulation of Tau in

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neurofibrillary tangles(NFT). This leads to positive feedback of loop where calcium
influx through N-methyl-D-aspartate-sensitive glutamate receptors (NMDAR).

Figure 4: diagram of excess of zinc in Alzheimer’s disease pathology (Nuttall ;
Oteiza, 2014)

C. Zinc in Male Reproductive System
For men who plans to have a family, zinc is important for their reproductive
system. Zinc is mostly found in the prostate gland (Oldereid, Thomassen,
Attramadal, Olaisen, ; Purvis, 1993). It is a small size gland that is located in the
pelvis which is in the middle of penis and bladder. Testicular development, sperm
maturation and testosterone synthesis are dependent to zinc. Low testosterone and
low concentration and mortality of sperm may be due to zinc deficiency. Low
concentration of zinc can give a bad effect to prostate gland which leads to an

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infection (prostatis) where the size of prostate gland becomes swollen (Bhowmik ;
Chiranjib, 2010). It is known as Benign Prostate Enlargement (BPE) whereby the
prostate gland will press the bladder and urethra. When the urine passes through it,
there will be difficulties in excreting but somehow it is not cancer. Male reproductive
system is related to production of semen. Prostate gland is like a factory for
production of semen. Semen is a mixture of sperm cells and other fluids. The fluid
itself contains zinc which comes with selenium that is secreted by the prostate gland
(Oldereid, Thomassen, ; Purvis, 1998). Changes in amount of zinc in body parts can
influence the sperm proliferation, maturation and viability (Teliiman et al., 2000). In
addition, when the level of concentration of zinc is insufficient, it will prevent the
production of luteinizing and follicle stimulating hormones from pituitary gland which
is related to testosterone production (Bhowmik ; Chiranjib, 2010). Hormones plays a
big role in the reproduction system and it can also affect the increase or
decreas(Hamdi, Nassif, ; Ardawi, 1997)e of weight. Testicular development is
important in the production of testosterone’s hormone. A study reported that
testicular failure is related to zinc deficiency (Endre L. et al,1990;Hamdi et al., 1997).
This statement was proven after conducting the experiment on rats for 6 weeks
where the result showed the concentration of testosterone and progesterone to
decrease but increase in follicle stimulating hormone (FSH) serum. Severe zinc
deficiency also depletes the production of normal germ cell which are dependent on
Sertoli cell hormone stimulation (Dym M. et al,1971;Ressell L. et al,1987;Hamdi et
al., 1997). However, the failure in testicular growth are not only affected by the
amount of zinc but it is also affected by protein and energy intake due to loss of
appetite.

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Based on the experiment conducted, severe zinc deficiency can weaken
spermatogenesis. Spermatogenesis is a mechanism for production of sperm cell in
testes by developing the germ cells in seminiferous tubules into haploid
spermatozoa. Meanwhile, seminiferous tubules are shrunken and the weight of
testicular is decreased.
i. Toxicity of zinc oxide nanoparticle in male reproductive system.
Zinc oxide nanoparticle (ZnONp) moves freely in the surroundings. It plays a
role in various industries including in cosmetics, pigments, biosensors, bioimaging,
drug delivery and antibacterial agents. Impairment of blood-testes barrier is the
consequence from zinc oxide nanoparticle which decreases the expression of the
gap junction proteins in Sertoli cells. Meanwhile, zinc oxide nanoparticle changes the
structure of cell membrane and mitochondrial outer membrane of Sertoli cell in-
order-to disrupt blood-testes barrier. It leads to an increase in the activity of reactive
oxygen species or oxidative stress activity in Sertoli cell. Activation of oxidative
stress cause secretion of cytokine to occur which can damage the blood-testes
barrier. Blood-testes barrier is located in between Sertoli cells which isolates further
developed stage of germ cells. (wikipedia)

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Figure 5: blood-testis barrier in between sertoli cell(8).
(https://en.wikipedia.org/wiki/Blood%E2%80%93testis_barrier#/media/File:Germinal_
epithelium_testicle.svg)

Figure 6: schematic summary of mechanism of zinc oxide nanoparticle impact on
male reproductive system in Sertoli cell and spermatocyte (Liu et al., 2016)

It was reported that zinc oxide nanoparticles can lead to more production of
oxidative stress and reactive oxygen species(ROS) generation (Bondareko al
et.,2013;Liu et al., 2016). DNA damage could also occur due to ROS generation
which are caused by the present of zinc oxide nanoparticle (Cai et
al.2009;Hackenbergh et al.,2010, Li et al.,2002;Liu et al., 2016). Generating ROS

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also activates the production of trk-TNF-a pathway which disrupts blood-testes
barrier.
ii. Prostate Cancer
One of the factor that can cause prostate cancer is lack of accumulation of
zinc in prostate gland which are located in the peripheral zone of prostate.
Malignancy of prostate cell mostly occur in peripheral zone (Costello & Franklin,
2006). Usually, the zinc level and citrate level are depleted in early stage of
malignancy development. Metabolic transformation is the transformation of citrate-
oxidatives that can accumulate zinc into citrate-oxidatives that cannot accumulate
zinc. When accumulation of zinc is decreased, m-aconitase activity will start to active
(Costello & Franklin, 2006). Metabolic transformation also involves the
transformation of neoplastic cell which activates the process of malignancy of
prostate cell (Costello L.C. & Franklin R.B.,2006; Costello L.C. & Franklin R.B.,2012;
Costello L.C. et al.,2015;Franklin, Zou, Zheng, Naslund, & Costello, 2016). When
normal cell experience genetic transformation into neoplastic phenotype, it is then
called as malignant cell. Neoplastic cell undergo transformation such as metabolic
transformation to provide synthetic requirements of malignancy.

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Figure 7: the concept of metabolic development of malignant cells (Costello &
Franklin, 2006)

It is believed that when prostate malignancy occurs, the zinc uptake
transporter (ZIP1) is inhibited. Inhibition of ZIP1 will reduce the amount of zinc and
decrease the cell tumor suppressor in prostate. Every disease has their own
treatment. Study reported that zinc ionophore can treat patient with prostate cancer.
The experiment was conducted to prove zinc ionophore can suppress malignant cell
of prostate by applying a suitable concentration on mice equivalent to that used in
human without giving bad effects (Franklin et al., 2016).

Figure 8: diagram of malignant cell and advanced malignancy is treat with clioquinol
which can increase uptake accumulation of zinc (Franklin et al., 2016)
https://en.wikipedia.org/wiki/Blood%E2%80%93testis_barrier

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D. Significance of Zinc for Skin
There are three important categories that are partially overlapped for skin
functions which are morphogenesis, repair and maintenance and protection.
Somehow, zinc is involved in all of the categories mentioned above, (Schwartz et al.,
2005). Zinc in the form of protein complexes are located intracellularly and in
extracellularly matrix (ECM) within the epidermal and dermal tissues. There, zinc
functions as a stabilizer of cell membranes and an essential cofactor. Additionally,
zinc plays a big role in mitosis, migration and maturation,(Lansdown et al., 2007).

Figure 9: An overview of the key functional steps in the wound-healing process of
skin with an indication of the places and functions of zinc in this process (Schwartz et
al., 2005)

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From the diagram above, we can observe that zinc and zinc-containing
proteins plays a role in almost every step of cutaneous wound reparation. Zinc is
involved during the mitigation of extracellular matrix, cell migration, protein synthesis
and in reduction of inflammation (Schwartz et al., 2005). Moreover, it is also used as
a catalyst for enzymes that is in-charge of DNA replication, gene transcription and
RNA. At a cellular level, zinc is important in order for cells to survive and at the end
affecting signal transduction, transcription and replication (Rostan et al.,2002). Other
than that, marginal zinc status in body also induce the levels of lipid peroxidation in
mitochochondrial and microsomal membranes and the osmotic fragility of erythrocyte
membranes which has something to do with the human body’s skin (Stefanidou et
al., 2006)
Based on Schwartz et al.,2005, improvements were observed when wounds
were exposed to zinc. Direct application of products containing zinc oxide showed
promising results as it improves leg ulcers and when tending to wounds that require
dressings. As we all know, zinc is not only limited to oral supplementation. Those
that are normally used are zinc sulfate and zinc oxides. Zinc sulfate are used in
lotions to promote granulations of indolent ulcers and in aqueous solutions to reduce
chronic inflammation in conjunctivitis. Zinc oxide on the other hand is mostly used in
ointments, pastes and lotions that is used by many to control various skin problems
as zinc oxides are a protective astringent and consist of antiseptic properties. Other
than that, daily zinc supplements that consists of elemental zinc such as zinc sulfate
and zinc gluconate are also recommended in order to speed up the wound healing
process.
To top it off, zinc reduces the risk of cancer and cardiovascular diseases and
protects skin from ultraviolet radiations. However, consuming calcium and zinc at the

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same time could prevent zinc absorption in the human body and so calcium and zinc
supplements are not recommended to be taken at the same time, (Rostan et al.,
2002)

E. The significance of zinc in pre-menstrual syndrome and during pregnancy

i. Effects of zinc in Pre-menstrual syndrome

Studies shows that low concentration of zinc in women can cause pre-menstrual
syndrome. Symptoms of pre-menstrual syndrome includes emotional, tension and
fluid retention. These symptoms are experienced by women in the days right before
menstruation. According to studies, PMS affects 50% of menstruating women,
(Bhowmik ; Chiranjib, 2010). It is also said that intake of zinc that is about or more
than 15 mg/day showed a decrease risk of having PMS (Nierenberg,2013). Zinc
regulates the secretion of hormones and progesterone and so low concentrations of
zinc leads to a reduction in secretion of progesterone and endorphins. Women facing
PMS was found with lower levels of zinc during the luteul phase of menstruation.
Moreover, deficiencies of this mineral also co-relates to symptoms that is related to
moods such as depression and menstrual cramps (Nierenberg,2013). With the help
of zinc, it can increase blood flow or diminish inflammation in the uterus, preventing
muscle cramps (Tremblay, 2018). According to the University of Maryland Medical

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Center, it is recommended to take multivitamins containing zinc in order to lessen
premenstrual syndrome.

ii. Effects of zinc during pregnancy
Based on Roohani et al, 2013, reproductive events can be affected if a
pregnant woman is deficit of zinc, copper and magnesium. These reproductive
events include infertility, pregnancy wastage, birth defects, pregnancy-induced
hypertension, placental abruption, premature rupture membranes, fetal growth
retardation, still birth and low birth weight. Sometimes birth defects can be identified
before birth, at birth or in some cases later in infancy such as hearing defects or
other kinds of defect (Kaur et al., 2014). Besides that, external defects of marginal
status of zinc during pregnancy also affects the appearance of the child such as
misshaped heads and fused or missing digits of the feet (King, 2000). The research
looking into the effects of zinc on immune functions in a healthy pregnant woman
showed that zinc induces the mitogenic influence on human lymphocytes exerting its
greatest proliferative influence in concentrations which is more than those in normal
human plasma. However, the proliferative responses of peripheral blood
lymphocytes to zinc were reduced to the same level as the phytomitogen PHA. As
pregnancy progresses, plasma level decreases and during birth, the micronutrient
level of zinc induces together with the increase of metabolism in both mother and
foetus (Raimi et al., 2012). Severe low intake of zinc gives impact to the duration of
gestation which is the development of foetus and can lead to an increase of risk for
preterm delivery (Kaur et al., 2014). During pregnancy, an additional of 100mg is
needed as 57% of the zinc consumed is deposited in the foetus and 24% is used in

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the uterine muscle (King, 2000). This additional need can be fulfilled by increasing
intake of zinc or adjusting zinc homeostasis. However, the adjustment of zinc
homeostasis will be much more in women that takes up low intake of zinc in their
diet. Based on King 2000, other factors such as smoking, alcohol abuse, acute
maternal infections, strenuous exercise and high doses of supplemental iron can
affect the capability to absorb or transport zinc to the foetus. Then, level of zinc in
body also can influence zinc absorption as zinc deprived humans absorb zinc
efficiently whereas those with high zinc diet does not absorb zinc well (Roohani,
Hurrel, Kelishadi, ; Schulin, 2013).
Another factor is the mechanism between copper and anti-copper action that
prevents the intestinal absorption of copper and so those with Wilson’s disease
should be given anti-copper therapy during pregnancy (Editorial, Page, & Al, 1997;
Kaur et al., 2014)Most of the time iron supplements are given to pregnant women. If
zinc supplements are also given, there’s a possibility that the influence of iron
supplements towards zinc status will be reduced and at the end risking the effect of
being deficient of both nutrients (Brien, Zavaleta, Caulfield, Wen, ; Abrams, 2018;
Kaur et al., 2014).
In terms of lactation, those who started pregnancy with a marginal zinc status
are usually zinc deficient as fetal growth requires an abundant concentration of zinc.
So, these mothers will lack zinc in their system and it affects the level of zinc in their
breast milk (Osredkar, 2011). Lactation describes the secretion of milk from the
mammary glands and the duration when a mother lactates to feed her young.
Premature infants are more susceptible to evolve zinc deficiency compared to a full-
term infant as they have insufficient body storage for zinc and their ability to absorb
zinc from the gut is defective. Generally, younger children require more nutrients as

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it is a critical stage for growth and so they are at risk of zinc deficiency. The first few
months, babies require sufficient zinc from their mothers which is through breast
feeding and then after that they can be fed by complementary foods containing
absorbable zinc (Roohani et al., 2013).
As woman ages, the zinc status in their body decreases because they tend to
eat less and the food they eat does not really have a large concentration of Zinc.
Additionally, excess estrogen reduces zinc status. Zinc is needed at this point in
order to slow down the progression of the disorder of retina (Bhowmik ; Chiranjib,
2010).
4.0 Effect of high concentrations of zinc to human body
Zinc is type of mineral which must be taken in small amounts for good health
as taking too much also has its downfall. There are three ways where zinc could
have entered the human body which are through inhalation, through skin or through
ingestion. Humans could be exposed to zinc-containing smoke especially when they
are working or involved in the industrial processes like galvanization. Other than that,
military smoke bombs consist of zinc oxide or zinc chloride that could be harmful to
human when inhaled. Soldiers are usually the first to be exposed when it comes to
smoke bombs. In some cases, soldiers could develop Adult Respiratory Distress
Syndrome (ARDDS) and without proper treatment, it could lead to a certain death,
(Plum et al., 2010). Being exposed to the smoke containing zinc oxide during the
smelting or welding of zinc can also lead to Metal Fume Fever (MFF). However, the
effect is not as life threatening and the respiratory effects will go away after a while.
In terms of dermal exposure, there are no proper evidence that it is harmful to
the skin as lotions, ointments and other products consists of zinc substance.

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Zinc ingestion does not affect the human body. However, zinc sulphate is
toxic for the body. Additionally, too much of zinc intake could reduce the
concentration of copper in the body. The recommended daily intake of zinc is roughly
about 15 mg/day (Raimi, O.G., Falade, O. A., Folorunso, O. S. and Lawal ;
Department, 2012; Tapiero ; Tew, 2003). Copper is mostly concentrated at areas in
the body where metabolic activities are carried out such as kidneys, livers, heart and
brain.

Figure 10: Diagram shows the effect of too much zinc and effect of being zinc
deficient at different parts of the body (Plum et al., 2010).

Zinc excess also affect human’s immune system. It causes the immune
function to work more than it is supposed to especially mitogenic response and

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macrophages or T-lymphocyte functions. In adults, it will lead to deterioration of
lymphocyte proliferative responses and a reduction in chemotaxis and phagocytosis
of circulating polymorphonuclear leukocytes, (Dardenne, 2002). In children on the
other hand, it will end up inducing anaemia, growth retardation and copper
deficiency.
Symptoms of excess zinc which is between 50 to 150 milligrams in the body
are as follows: nausea, vomiting, diarrhoea, abdominal cramps, loss of appetite and
headaches. More severe bio-markers include shortness of breath, yellow skin,
dizziness and chest pain (Bruso,J, 2018)

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Conclusion
As we mentioned earlier, we did a review on the trace element, zinc as our
research project. It is believed that zinc is the second highest component present in
our body after iron. It plays an important role in the human body as it is needed for
biological roles, the catalytic, the structural and the regulatory action. From our
understanding, zinc binds with some of enzymes out of 300 types of enzymes
present in our body. Zinc does not only focus on the growth of our health but also
focuses on the well- being of our biological system. It is crucial for the structure and
function of various proteins such as metallothein, MTs for zinc homeostasis and
plays important role for human bodily processes from its involvement in function of
the immune system, male and female reproductive system and in organ of human
body like skin and brain. in addition, Alzheimer’s disease and cancer are correlated
with the excess or deficiency of zinc. However. It can be a problem if our body have
an excess accumulation of zinc or lack amount of zinc. It must be balance in
concentration of zinc which is suitable for each part of body to be a healthy person.
Many have used zinc supplementation for treatment of various disease related to
zinc deficiency.

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