Zinc: An Essential Trace Element with Powerful Health Benefits

What is Zinc?

Zinc is an essential mineral present in every organ, tissue, and fluid of the human body.

It is the second most common trace element after iron and plays a vital role in numerous biological functions, including:

• Energy production
• Tissue formation
• Muscle building

Zinc Effects on the Body

1. Immune System Support

• Zinc is vital for the development and function of immune cells, especially white blood cells.
• It helps the body fight infections by boosting immune response and reducing inflammation.
• Zinc deficiency weakens immunity, making infections more frequent and severe.

2. Antioxidant and Anti-Inflammatory Effects

• Zinc acts as an antioxidant, protecting cells from damage caused by free radicals.
• It reduces chronic inflammation, which is linked to many diseases such as heart disease and diabetes.

3. Wound Healing and Tissue Repair

• Zinc accelerates wound healing by supporting cell growth and division.
• It promotes tissue regeneration and skin repair, helping recover from injuries or skin conditions like acne and eczema.

4. Growth and Development

• Essential for normal physical growth in children and adolescents.
• Supports muscle growth and tissue formation in all ages.
• Plays a role in DNA synthesis and cell division, critical for development.

5. Hormone Regulation

• Influences the production and function of key hormones including testosterone, insulin, and thyroid hormones.[1]
• Supports reproductive health and sexual function.
• Helps regulate blood sugar levels through insulin activity.

6. Sensory Functions

• Zinc is crucial for maintaining normal taste and smell perception.
• Deficiency can lead to diminished senses or altered sensory experiences.

7. Cognitive Function

• Supports brain health and cognitive processes such as learning, memory, and concentration.
• Zinc deficiency has been linked to mood disorders like depression and increased anxiety.

8. Bone, Hair, and Nail Health

• Zinc strengthens bone structure and supports bone density.
• Promotes healthy hair growth and prevents hair thinning or loss.
• Maintains nail strength and integrity, preventing brittleness and white spots.

Importance of Regular Zinc Intake

• Zinc is continuously used by the body and must be replenished daily through diet.
• A deficiency can impair multiple systems and lead to significant health issues.

Groups at Risk of Zinc Deficiency

• People with digestive disorders that reduce nutrient absorption.
• Vegetarians and vegans, due to lower zinc absorption from plant foods containing phytates.
• Pregnant and lactating women with higher zinc needs.[2]
• Alcoholics and people with sickle cell disease. [1]
• Competitive athletes with increased zinc requirements.

Symptoms of Zinc Deficiency

There is no other substance that can replace zinc in the human organism. If an adequate supply is not regularly guaranteed, a zinc deficiency can occur. A moderate deficiency usually leads to unspecific systematic symptoms that often go undetected for a long time.

Possible symptoms of zinc deficiency include: [3] [4] [5] [6] [7] 

• Fatigue, lack of drive
• Lack of concentration, poor learning
• Increased susceptibility to infections and inflammation
• Bad wound healing
• Inflammatory skin changes
• Hair loss, thinning hair
• Brittle nails, white spots on the nails
• Impaired growth
• Decreased sexual interest
• Disorders of sensory perception
• Fungal infections
• Athlete's foot
• Mood swings
• Depression
• Anaemia
• Loss of weight and/or appetite
• Developmental disorders (in children)
• Growth disorders (in children)
• Rash and skin lesions

Zinc Dosage

Sometimes even with a varied diet, the daily zinc requirement cannot be adequately covered. In normal cases, an amount of 9-10 mg is assumed for men, while women need about 7 mg of zinc per day.

The daily intake of zinc recommended by the German Nutrition Society (DGE) is age and weight dependent, with different guideline values for men and women.

The following guidelines are stated in milligrams (mg) per day: [8] 

For people with a zinc deficiency or an increased zinc requirement, dietary supplements in the form of zinc tablets or zinc capsules can provide useful support for the supply of zinc to the human body.

Zinc in Food Sources

Best Animal Sources (well absorbed):

• Red meat
• Oysters and other seafood
• Dairy products
• Some cheeses

Plant Sources (less absorbed due to phytates):

• Legumes (beans, lentils)
• Nuts and seeds
• Whole grains
• Fortified cereals

Zinc Supplementation

• Supplements can help those with deficiency or increased needs (athletes, pregnant women, restrictive diets).
• Zinc is available in tablets and capsules.
• Always follow dosage recommendations to avoid toxicity.

Zinc Side Effects and Overdose

• Maximum safe intake: 40 mg/day (adults)
• Acute overdose: Nausea, vomiting, diarrhea, abdominal cramps, headache
• Chronic overdose (≥150 mg/day):
• Disrupts copper and iron balance
• Weakens immune system
• Avoid exceeding recommended doses.[9]

Who Especially Needs Zinc?

• Athletes
• People with a zinc deficiency
• People with skin problems
• Pregnant and breastfeeding women
• People with a weakened immune system
• People who have an increased need for zinc due to taking medication
• Vegans and vegetarians

Zinc and the Immune System

Zinc is essential for the normal development and function of many immune cells. [10] Even a mild deficiency can impair immune function and increase the risk of bacterial, viral, and parasitic infections.[11]

How Zinc Supports Immune Health

• Supports the development and activation of immune cells, especially T-lymphocytes and natural killer (NK) cells
• Regulates inflammatory response and immune signaling pathways
• Promotes barrier integrity of the skin and mucosal membranes, preventing pathogen entry

 Zinc supplementation has shown significant benefits in individuals with immunodeficiencies, such as: [12] [13] 

• Sickle cell disease
• HIV infection
• Down syndrome
• Elderly individuals with weakened immunity

In these groups, zinc has been shown to:

• Restore NK cell activity
• Improve lymphocyte production
• Increase resistance to infections

Note: In HIV patients with low zinc levels, long-term supplementation has been associated with:

• Fewer opportunistic infections
• Reduced risk of immunological decline [14] [15]
  ⁠However, excessive zinc intake may worsen symptoms in some cases and should be managed carefully. [16] [17]

People with acrodermatitis enteropathica, a genetic disorder impairing zinc absorption, experience high rates of infection.[18]

Therapeutic zinc supplementation in these patients leads to complete recovery of immune function and general health.

Research shows that zinc supplementation reduces the severity, duration, and recurrence of several infectious diseases, particularly in infants and children in developing regions. These include:

• Acute and chronic diarrhea
• Acute lower respiratory tract infections
• Malaria [19] [20]

Zinc also shows beneficial effects in the treatment or prevention of:

• Shigellosis (bacterial dysentery)
• Leprosy
• Tuberculosis
• Leishmaniasis
• Hepatitis C
• The common cold (via increased production of Th1 cytokines) [21] [22]

While zinc is essential, too much can suppress immune function.

In a study of healthy young men, high-dose zinc supplementation led to:

• Reduced lymphocyte activation
• Decreased neutrophil phagocytosis [23]
• Overall weakened immune defense

Conclusion: Balance is key. Zinc supplementation can significantly enhance immune function when deficient, but excess zinc can impair it.

Antioxidant Properties of Zinc

Zinc functions as a powerful antioxidant, protecting cells from oxidative damage by stabilizing membranes, reducing reactive oxygen species (ROS), and preserving cellular integrity. [24] 

Key Research Findings:

• In elderly individuals, zinc supplementation significantly reduced fat peroxides in the blood, a marker of lipid oxidation. [24]
• In women, zinc reduced DNA strand breaks, which are indicators of oxidative stress damage. [25]
• In men with asthenospermia (poor sperm motility), zinc helped restore normal levels of superoxide radical scavengers, improving sperm health. [26]
• Zinc protected mice from radiation-induced oxidative stress, suggesting its broader protective effect at the cellular level. [27]
• In Wilson’s disease, where copper accumulates in tissues and causes oxidative damage, zinc therapy has proven effective in reducing symptoms by modulating metal balance. [28]
• Zinc also protects skin cells from oxidative damage caused by free radicals and bacterial toxins. [29] [30]

Zinc and Inflammation

Zinc plays a critical role in modulating inflammatory responses, largely by suppressing the transcription factor NF-kB, which regulates the production of inflammatory cytokines. [10] 

Findings:

• Zinc inhibits the release of pro-inflammatory cytokines (e.g., TNF-α, IL-1β).
• In elderly individuals, a population often deficient in zinc, supplementation led to a reduction in systemic inflammation. [31] [32]
• Zinc supplementation has shown effectiveness in managing chronic inflammatory conditions such as:
• Irritable Bowel Syndrome (IBS)
• Acne
• Asthma [33] [34]
• In aged mice, zinc prevented age-related increases in inflammatory markers, highlighting its anti-aging potential.

Zinc and Autoimmune Regulation

Zinc plays a dual role in the immune system, enhancing protective immunity while suppressing harmful autoimmune responses. [35] [36] 

Mechanisms and Evidence:

• Zinc promotes the development of regulatory T-cells (Tregs), which suppress autoimmune activity and promote immune tolerance.
• In healthy men, zinc supplementation helped reduce graft rejection while maintaining infection resistance.
• In mouse models of multiple sclerosis and arthritis, zinc: [37] [38] [39]
• Reduced disease symptoms
• Suppressed T-cell proliferation
• Increased Treg levels
• Decreased inflammatory cytokine release
• Zinc reduced heart transplant rejection in mice by:
• Inhibiting caspase-3, an enzyme involved in graft tissue death [40]
• In rheumatoid arthritis patients, zinc therapy improved: [41] [42] [43]
• Joint swelling
• Morning stiffness
• Walking time

Zinc in Allergy and Asthma Management

Zinc is increasingly recognized for its role in allergy control and respiratory health.

• In individuals allergic to grass pollen (a major cause of allergic rhinitis), zinc:
• Increased regulatory T-cells
• Decreased immune cell proliferation in PBMCs [44]
• In children, low zinc levels are correlated with more severe asthma symptoms. [45]
• Zinc supplementation in asthmatic children improved symptoms including: [32] [46]
• Coughing
• Wheezing
• Shortness of breath
• In mouse models:
• Zinc reduced airway inflammation and hyper-reactivity
• Inhibited epithelial cell death in the respiratory tract by blocking caspase-3

Zinc and Wound Healing

Zinc is essential for tissue repair, skin regeneration, and post-surgical recovery.[47] 

Evidence and Applications:

• Zinc deficiency is linked to delayed wound healing and increased risk of skin infections. [48]
• In diabetic patients, zinc supplementation improved the healing of chronic skin ulcers.
• Animal and human studies show that zinc accelerates healing after:
• Burns
• Surgical wounds
• Traumatic injuries
• Topical zinc oxide application significantly enhanced wound closure in rats with excisional skin wounds.

Zinc for Mental Function

Zinc supplementation has demonstrated several benefits for cognitive function, especially in zinc-deficient individuals and neurological conditions:

• Ischemic Stroke Recovery: Zinc supplementation improves cognitive recovery in zinc-deficient people who have experienced an ischemic stroke. [49]
• Child Cognitive Performance: A double-blind study in children found that zinc supplements led to superior neuropsychological performance, particularly in attention and reasoning skills, compared to controls. [50] [51]
• Infant Development: A randomized study showed that zinc supplementation increased activity levels, intellectual development, and motor skills in infants and young children. [52] [53]
• Alzheimer’s Disease: In older patients with Alzheimer's disease, zinc therapy helped protect against cognitive decline by lowering free copper levels in the blood, which are toxic to the brain. [54] [55]
• Animal Studies: Numerous animal studies indicate that zinc, at moderate concentrations, is neuroprotective and helps maintain learning and memory functions. [56] [57]
• Alzheimer’s Mouse Model: Zinc supplementation reduced pathological factors associated with disease progression (e.g., β-amyloid and tau protein accumulation) and improved mitochondrial function and brain-derived neurotrophic factor (BDNF) levels in the hippocampus.
• Maternal Supplementation: Maternal zinc supplementation enhanced spatial learning and memory in rat offspring.
• ALS Model: Moderate doses of zinc (12 mg/kg) prolonged survival in an amyotrophic lateral sclerosis (ALS) mouse model. [58]

Zinc and Psychiatric Disorders

Research suggests that zinc supplementation may provide benefits when used alongside conventional treatments for certain psychiatric disorders:

• Obsessive-Compulsive Disorder (OCD): In patients with OCD, adding zinc to fluoxetine therapy significantly reduced symptoms, as measured by the Yale-Brown Obsessive-Compulsive Scale. [59] The improvement may be due to zinc’s ability to suppress glutamate release and transmission, which are involved in OCD pathology. [60]
• Attention-Deficit/Hyperactivity Disorder (ADHD): A study found that zinc supplementation combined with methylphenidate (a central nervous system stimulant) helped reduce hyperactivity and impulsiveness in children with ADHD. [61] [62]
• Schizophrenia: In male patients with schizophrenia, zinc supplementation alongside risperidone improved several symptoms, including aggression, hallucinations, and delusions. This benefit is thought to be related to zinc’s antioxidant and antidepressant effects. [63]

Zinc and Autism

Research indicates a potential link between zinc levels and autism spectrum disorder (ASD):

• Lower Zinc Levels in Autism: One study found that individuals with autism have lower zinc levels compared to non-autistic controls. Treatment with zinc combined with vitamin B6 was associated with a reduction in the severity of autistic symptoms, including consciousness, hyperactivity, receptive language, focus and attention, eye contact, sneaking behavior, sensitivity to sound and touch, and seizures. [64]
• Prenatal Zinc and Autism-like Behaviors: Animal studies suggest prenatal zinc supplementation can prevent autistic-like behaviors in offspring. In rats, zinc treatment reduced social deficits, repetitive behaviors, and cognitive inflexibility, highlighting a possible role of zinc deficiency in autism development. [65]
• Zinc’s Role in Brain Cell Communication and the Shank3 Protein: Recent research has focused on the Shank3 protein, which is critical for synaptic function and is associated with neurodevelopmental disorders such as autism and schizophrenia. Genetic mutations in Shank3 lead to significant communication and behavioral deficits.
• Despite genetic changes in Shank3, brain cells retain their ability to respond to zinc.
• Zinc supplementation was shown to enhance brain cell communication that had been weakened by autism-related Shank3 mutations.
• Disorders affecting zinc regulation can impair synaptic function and contribute to cognitive and behavioral issues in psychiatric disorders.
• Implications: These findings suggest that environmental and nutritional factors, such as zinc levels, can modulate the signaling pathways involving Shank3 and influence neuronal function and behavior in autism.

Zinc for Stress and Mood

• Zinc supplementation has demonstrated effectiveness in managing mood disorders such as depression and anxiety, both in clinical settings and animal models.
• One of the mechanisms behind this effect is zinc’s ability to increase brain-derived neurotrophic factor (BDNF) levels, which are typically reduced in individuals with depression.
• For example, a study found that zinc therapy improved overall mood in overweight participants, potentially through the upregulation of BDNF.

Zinc Controls Cell Death

Both excessively high and abnormally low intracellular zinc concentrations can trigger apoptosis, a form of programmed cell death, in various cell types. [66] [67] 

Zinc Deficiency and Cancer

Zinc deficiency has been linked to an increased risk of developing certain cancers, particularly in the digestive tract:

• Digestive Tract Cancers: Zinc deficiency significantly raises the risk of cancers of the mouth, esophagus, and stomach. These tissues are especially vulnerable due to their high exposure to external toxins.
• Other Cancers: Low blood zinc levels are also associated with cancers of the head, neck, lungs, gall bladder, prostate, and ovaries. [68]
• Immune Function: Restoring zinc levels can enhance natural killer (NK) cell function, which plays a critical role in identifying and destroying tumor cells. [69] [70]
• Antitumor Effects: Zinc may inhibit tumor growth by reducing glucose uptake in cancer cells, preventing angiogenesis (the formation of new blood vessels), and inducing apoptosis (programmed cell death) in cancer cells, as demonstrated in both animal and human studies. [71] [72] [73] [74]

Zinc as an Antimicrobial Agent

Zinc exhibits antimicrobial effects, particularly at higher doses:

• Zinc inhibits the growth of various bacteria, especially gram-positive organisms.
• It has demonstrated antibacterial activity against both aerobic and anaerobic bacteria found in root canals.
• Zinc suppresses the accumulation and growth of Staphylococcus aureus in skin tissue. [A193]]
• Additionally, zinc shows antimicrobial effects against common wound flora in animal models such as rats. [75]

Zinc and Epilepsy

Several studies have reported significantly lower zinc levels in the blood of patients with persistent epilepsy. [76] [77] 

• In one study involving epileptic children, zinc therapy reduced the frequency of seizures in 31% of those treated. [78]
• Animal research has shown that zinc supplementation can increase the latency period—the time between seizures, in rats experiencing febrile seizures. [79]

Zinc Promotes Growth

Multiple studies have demonstrated that zinc supplementation positively affects growth in children, particularly those who are underweight or experience stunted growth. [80] [81] 

• A comprehensive analysis found that daily supplementation with 10 mg of zinc for 24 weeks led to an average height increase of approximately 0.37 cm compared to placebo. [82]
• In addition to promoting linear growth, zinc supplementation has been shown to increase muscle mass in children. [83]

Zinc and Gut Health

Zinc supplementation has protective effects on the intestinal mucosa in both animal models and humans across various gastrointestinal conditions:

• Zinc helps stabilize the intestinal lining and reduces injuries in the stomach and small intestine by enhancing repair processes, as demonstrated in rats and mice.
• It protects the intestinal mucosa from alcohol-induced damage in animal studies.
• Zinc supplementation can prevent increased intestinal permeability (“leaky gut”), which is associated with a reduced risk of inflammatory bowel disease (IBD). [84]
• In patients with dyspepsia, inflammation linked to Helicobacter pylori-induced gastric cancer was inversely correlated with zinc levels, suggesting zinc may reduce gastric cancer risk by suppressing gastric inflammation. [85]

Zinc and Sleep Quality

Higher blood zinc concentrations are associated with better sleep quality in women and children. [86] Additionally, a study in infants found that zinc supplementation increased the duration of sleep.

Zinc Promotes Appetite

Loss of appetite is one of the earliest signs of zinc deficiency. [87]

• In animal studies, oral zinc supplementation significantly increased food intake in rats by elevating levels of appetite-regulating neuropeptides such as orexin and neuropeptide Y.
• Clinical research in patients with anorexia nervosa (AN) has revealed a strong association between low blood zinc levels and the disorder. [88] [89]
• Multiple studies report that oral zinc supplementation in AN patients leads to improvements in weight gain, muscle mass, appetite, taste sensitivity, and overall food intake. [90] [91] [92]

Zinc and Skin Health

Zinc has demonstrated benefits for a wide range of skin conditions, including acne, warts, rosacea, eczema, psoriasis, melasma, and dandruff: [A122]

• Acne Vulgaris: Dietary zinc supplementation significantly improves acne symptoms compared to placebo. [A216] [93]
• Viral Warts: Clinical studies show that zinc treatment leads to the complete resolution of warts in the majority of patients. [94] [95]
• Genital Herpes: Zinc exhibits efficacy in treating genital warts caused by herpes simplex virus (HSV) types 1 and 2. [96]
• Rosacea: Oral zinc supplementation reduces symptoms of rosacea, a chronic inflammatory skin disease characterized by facial redness and bumps. [97]
• Inflammatory Skin Conditions: Zinc’s anti-inflammatory and antioxidant properties make it effective in managing psoriasis, eczema, and seborrheic eczema (dandruff). [98] Zinc-containing shampoos significantly reduce scaling and inflammation associated with dandruff. [99]
• Melasma: Zinc treatment reduces the severity of melasma, a pigment disorder causing brown discoloration, with minimal side effects. [100]
• Sun Protection: Zinc also protects the skin against UV damage, which contributes to skin aging and cancer. Notably, a human study found that oral zinc supplementation provided better protection against UV radiation than titanium dioxide. [101]

Zinc and Hair Loss

Zinc plays a significant role in maintaining healthy hair, and its deficiency has been linked to various forms of hair loss:

• Male Pattern Baldness: A clinical study found that topical zinc application improved hair growth in men with baldness. Zinc's antimicrobial, anti-inflammatory, antioxidant, and anti-androgenic properties may contribute to increased hair density and scalp health. [102] [103] [104] [105]
• PCOS-Related Hair Loss: In women with polycystic ovarian syndrome (PCOS), zinc supplementation improved several symptoms, including alopecia (hair loss). [106]
• Post-Surgical Hair Loss: Zinc treatment has also been shown to reverse hair loss in patients who experienced zinc deficiency following vertical gastroplasty (gastric stapling surgery). [107]

Zinc and Liver Protection

Zinc plays a protective role in liver health across various liver diseases:

• Alcoholic Liver Disease (ALD): In animal models, zinc supplementation significantly protected the liver by blocking key mechanisms of liver injury, including increased intestinal permeability, endotoxemia, oxidative stress, overproduction of inflammatory cytokines, and liver cell death. [108] [109]
• Non-Alcoholic Cirrhosis: In patients with non-alcoholic cirrhosis, zinc supplementation improved liver function and helped prevent excess copper accumulation, a factor that can worsen liver damage.
• Hepatitis C: Zinc supplementation has also been shown to improve outcomes in patients with hepatitis C, a viral infection that can lead to liver scarring if left untreated.

Zinc for strong bones

Zinc plays a key role in maintaining strong and healthy bones by promoting bone formation and preventing bone loss:

• Bone Density and Strength: Research has shown that zinc supplementation can increase bone density and enhance bone strength by supporting the activity of bone-forming cells.
• Osteoblast Activation: In mice, zinc treatment stimulated osteoblast activity, which is essential for bone formation.
• Bone Formation Markers: In healthy men, zinc supplementation was associated with increased levels of bone formation markers such as alkaline phosphatase (ALP), BAPE, and BAP-M. [110]
• Bone Resorption Suppression: Zinc was also shown to suppress bone resorption activity in mouse bone marrow cultures by reducing the expression of bone-degrading factors like parathyroid hormone (PTH) and prostaglandin E2 (PGE2). [111]
• Protection Against Bone Disorders: Due to these effects, zinc has demonstrated protective benefits against various bone-related conditions in both animal and human studies. [112] [113]

Zinc and Heart Health

Zinc plays an important role in cardiovascular function, and deficiency has been linked to various heart conditions:

• Zinc Deficiency and Heart Disease: Studies have found that individuals with arteriosclerosis (hardening of the arteries), heart disease, chest pain (angina), and heart attacks often have lower zinc levels. [114] [115] [116] [117]
• Heart Failure: One study reported that zinc deficiency is associated with a higher incidence of heart failure. [118]
• Angina Treatment: High doses of zinc have been shown to help prevent and alleviate angina symptoms in patients with atherosclerosis. [118]
• Stroke Protection: In animal studies, zinc supplementation protected the heart from damage caused by stroke-related injuries. [115]

Zinc and Diabetes

Zinc plays a critical role in insulin function and glucose metabolism, and its deficiency is strongly associated with the development and progression of diabetes:

• Insulin Signaling: Zinc ions can bind to insulin receptors and activate insulin signaling pathways, helping regulate blood glucose levels. [119]
• Insulin Mimicry and Pancreatic Protection: By mimicking insulin, zinc reduces excessive insulin secretion from pancreatic β-cells, protecting them from overuse and damage. [120]
• Insulin Function: Zinc improves the solubility of insulin within pancreatic cells and enhances its binding to insulin receptors, contributing to better insulin activity. [121]
• Zinc Deficiency and Insulin Resistance: Because zinc is essential for the processing, storage, and secretion of insulin, a deficiency can lead to increased insulin resistance. [122]
• Zinc Deficiency in Diabetes: Studies have shown that prediabetic individuals are more likely to be zinc deficient, and high rates of zinc deficiency are commonly observed in patients with type 2 diabetes. [121] [123]
• Prevention: Research in women has found that higher dietary zinc intake is associated with a reduced risk of developing type 2 diabetes. [124] [123]
• Supplementation Benefits: Zinc supplementation has been shown to lower fasting blood sugar levels and improve insulin sensitivity in both animal models and humans with diabetes. [125] [125] [126] [127]
• Additional Benefits: In type 2 diabetics, zinc has also been found to reduce the severity of diabetic neuropathy, oxidative stress, and abnormal lipid profiles (cholesterol and triglycerides). [128] [129] [127] [130]

Zinc and Diet

Zinc plays an important role in regulating appetite and metabolism through its influence on leptin, a hormone involved in appetite control and energy balance:

• Leptin Regulation: Zinc restriction has been shown to reduce leptin production in both rats and humans. Leptin is produced by fat cells and helps regulate hunger and body weight. [131] [132] [130]
• Zinc Repletion and Leptin Increase: In men with marginal zinc deficiency, restoring zinc levels led to increased blood leptin concentrations. This effect may be mediated through enhanced activity of immune factors such as interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-α), which are known to influence leptin expression. [133]

Zinc and Male Fertility

Zinc plays a vital role in male reproductive health, influencing sperm quality, hormone levels, and testicular function:

• Sperm Quality: Higher seminal zinc concentrations are positively correlated with improved sperm count, motility, and viability. [134] [135] [136] This is likely due to zinc’s role in stabilizing sperm cell membranes and DNA, reducing oxidative damage, and enhancing spermatogenesis (the formation of new sperm). [137]
• Animal Studies: Low to moderate doses of zinc supplementation (12–120 mg/kg) have been shown to improve reproductive function in male rats.
• Hormone Regulation: Zinc is highly concentrated in the prostate and testes and is essential for the synthesis of testosterone. In infertile men with low testosterone levels, zinc supplementation has been found to increase sperm count, testosterone, dihydrotestosterone (DHT), and overall fertility. [138]
• Libido and Sexual Function: Zinc’s testosterone-boosting effect may improve libido and sexual performance, especially in men with erectile dysfunction—a condition often linked to low testosterone. [139] [140] [141]
• Protection from Oxidative Stress: Zinc can reduce oxidative damage to the testes. In rat models, zinc supplementation preserved testicular function, including testicular weight, sperm concentration, and testosterone levels, even when exposed to oxidative stress from cigarette smoke.

Zinc on Fatigue

Zinc has been linked to the management of symptoms commonly seen in chronic fatigue syndrome (CFS), due to its role in immune function, antioxidant defense, and inflammation control:

• Zinc Deficiency in CFS: Low blood zinc levels are frequently observed in individuals with CFS and are associated with symptoms such as persistent fatigue, depression, and difficulty concentrating.
• Clinical Findings: One study found that zinc levels were significantly lower in patients with CFS compared to healthy controls. The severity of CFS symptoms was inversely correlated with zinc levels, suggesting that zinc supplementation may help reduce symptom burden through its antioxidant and anti-inflammatory effects. [142]
• Zinc and Gut Inflammation: Intestinal inflammation, often linked to increased intestinal permeability ("leaky gut"), is common in CFS. [143] A study showed that treating this condition with a combination of antioxidant and anti-inflammatory agents, including zinc, led to a significant improvement in CFS symptoms. [144]

Zinc and Athletic Performance

• Role of Zinc: Zinc supports the maintenance of hormone levels crucial for energy, recovery, and overall physical performance during intense training.
• Research Findings:
• A study on wrestlers showed that heavy training led to significant drops in thyroid hormones and testosterone, both important for energy and recovery.
• Zinc supplementation prevented these hormone declines, indicating that physiological doses of zinc can help sustain hormonal balance and reduce fatigue during strenuous exercise.
• Similar effects were seen in sedentary men, where zinc helped maintain healthy hormone levels, suggesting zinc’s broader potential to enhance athletic performance.
• Implication: Zinc supplementation may be beneficial for athletes or individuals undergoing intense physical training by supporting hormone balance and reducing exercise-related fatigue. [145]

Zinc and Blood Clotting

• Key Role: Zinc regulates both pro-thrombotic (clot-promoting) and anti-thrombotic (clot-preventing) factors produced by platelets and the vascular endothelium (inner lining of blood vessels). [146] [147]
• Effects of Zinc Imbalance:
• High Zinc Levels (Hyperzincemia): May lead to excessive blood clotting, increasing the risk of thrombosis.
• Low Zinc Levels (Hypozincemia): Especially when combined with low calcium (hypocalcemia), can impair platelet aggregation, prolong clotting time, and cause abnormal bleeding. [147]
• Supporting Evidence:
• A study on zinc-deficient men demonstrated that zinc supplementation restored normal platelet aggregation and clotting times, confirming zinc’s crucial role in maintaining proper coagulation. [148]
• Summary: Balanced zinc levels are vital for healthy blood clotting, preventing both excessive clot formation and abnormal bleeding.

Zinc in Pregnancy

Low blood zinc levels are linked to several pregnancy complications, including spontaneous abortion, pre-eclampsia, prolonged pregnancy, premature birth, and abnormal fetal development. [149] [150] [151] 

Research indicates that maternal zinc supplementation, particularly in women who are zinc-deficient or underweight, can lower the risk of premature birth and protect the fetus from alcohol-related damage. [152] [153] 

For example, a study involving Indian mothers showed that those who received additional zinc experienced longer pregnancies and delivered babies with healthier birth weights. Another study found that supplementing pregnant women with low zinc levels (25 mg/day) during the second half of pregnancy significantly increased infant birth weights and head circumference. [154] 

These benefits are believed to stem from zinc’s ability to:

• Inhibit embryonic cell death,
• Boost growth factors like IGF (Insulin-like Growth Factor), PDGF (Platelet-Derived Growth Factor), and FGF (Fibroblast Growth Factor),
• Reduce oxidative damage.

Together, these effects support healthy fetal development and growth. [149] [155] 

Zinc and Women's Health

1. Hormonal Balance and Menstrual Health

• Zinc deficiency is linked to hormonal imbalances affecting ovarian function.
• This can cause menstrual irregularities and infertility. [156]
• Zinc supplementation, alone or with mefenamic acid, can reduce the severity and duration of menstrual pain by inhibiting prostaglandin metabolism in the uterus, which reduces painful cramps. [151] [157] [158][159]

2. Polycystic Ovary Syndrome (PCOS)

• PCOS often involves insulin resistance, which increases androgen hormone levels (like testosterone and DHEA), causing symptoms such as balding, excessive body hair, irregular periods, and infertility.
• Zinc supplementation has been found to lower insulin levels in women with PCOS and improve symptoms, including hair-related changes. [160] [106]

3. Endometriosis

• Women with endometriosis often have low blood zinc levels. [161]
• Antioxidants including zinc have been linked to slower progression of endometriosis, suggesting zinc may help mitigate this condition. [161]

Zinc for pain

Animal Studies:

• In rats with sciatic nerve injuries, zinc chloride injections significantly reduced thermal hyperalgesia (heightened pain sensitivity) in a dose-dependent way. [162] [163]
• Zinc salts suppressed pain responses in mice exposed to various painful stimuli such as heat and chemical irritants. [162]

Human Evidence: Zinc supplementation reduced the frequency and severity of muscle cramps in patients with chronic liver disease. [164]

Proposed Mechanism: Zinc may relieve pain by acting as an antagonist to NMDA receptors, which play a key role in the initiation and transmission of pain signals in the nervous system.

Zinc for Taste Sensation

• Zinc Deficiency and Taste: Zinc deficiency is linked to reduced taste sensitivity. [165]
• Role of Gustin: Gustin (also called carbonic anhydrase VI) is a zinc-dependent enzyme found in saliva that helps maintain taste function. Low zinc levels reduce gustin activity, impairing taste. [166]
• Evidence from Studies: Supplementation with zinc has been shown to improve taste intensity. For example, in Indian adolescents, who commonly experience zinc deficiency, zinc supplements increased sensitivity to salty tastes. [167]

Zinc for Hearing Disorders

• Animal Studies: Zinc deficiency causes impaired hearing in mice and rats, which can be reversed with zinc supplementation. [168] This protective effect is likely due to zinc increasing superoxide dismutase (SOD), an antioxidant that shields ear structures like the cochlea and vestibule from toxins. [169]
• Tinnitus (Ringing in the Ears):
  ⁠People with tinnitus tend to have lower blood zinc levels. [170] [171]
  ⁠One study found that taking 50 mg of zinc daily for two months reduced tinnitus severity in 82% of patients. [170]
• Sudden Sensorineural Hearing Loss: Adding zinc supplementation to oral corticosterone treatment improved symptoms more effectively than corticosterone alone. [172]
• Otitis Media (Middle Ear Infection): Zinc supplementation significantly reduced the incidence of otitis media in healthy children from low-income communities. [173]

Zinc and Lifespan

• Role in Oxidative Stress: Oxidative stress accelerates aging by damaging cells. Zinc is a crucial part of the enzyme Cu/Zn superoxide dismutase (Cu/Zn SOD), which neutralizes harmful superoxide radicals. [174] [175]
• Research Findings:
  ⁠Studies in organisms like Saccharomyces cerevisiae (yeast) and mice genetically engineered to produce high levels of SOD showed increased lifespans.
  ⁠Mutations in the SOD gene are linked to age-related diseases such as ALS, Parkinson’s, Alzheimer’s, and cancer. [176]
• Inflammation and Aging: Chronic inflammation contributes to aging and related diseases. [177]
• Benefits of Zinc Supplementation in the Elderly:
  ⁠Zinc supplements have been shown to reduce inflammation, oxidative stress, and infection rates in older adults. [178]
  ⁠Given its antioxidant and anti-inflammatory effects, zinc can help promote longevity, particularly in the elderly who are prone to zinc deficiency.

Zinc and Thyroid Gland Function

Zinc Deficiency and Thyroid Function: Both animal and human studies show that zinc deficiency is linked to reduced thyroid activity, characterized by lower blood levels of triiodothyronine (T3) and free thyroxine (FT4). [179] [180] 

Zinc Supplementation Benefits: Supplementing zinc can improve thyroid function in humans.

Clinical Evidence:

• In hypothyroid patients with mild to moderate zinc deficiency (especially those on anticonvulsant therapy), zinc supplementation normalized thyroid hormones like T3 and FT3 and restored thyroid function. [181]
• A case study involving university students found that zinc intake raised thyroid hormone levels (T3 and T4) and improved metabolic rate.
• Zinc also seemed to counteract negative effects of radiation from computer monitors on thyroid hormone levels in computer users. [182]

Zinc and Chemotherapy

• Mucositis Relief: Mucositis, or ulceration of mucous membranes, is a common and painful side effect of chemotherapy and radiation therapy. Studies show that zinc supplementation can reduce the severity of oral mucositis in these patients. [183] [184]
• Improvement in Taste and Smell Disorders:
  ⁠Chemotherapy can cause dysgeusia (distorted taste) and dysosmia (distorted smell).
  ⁠One study reported that taking 100 mg of zinc daily for 4–6 months improved these symptoms, especially in patients with deficiencies in carbonic anhydrase VI (Gustin).
• Mechanism: Zinc stimulates production of carbonic anhydrase VI, a zinc-dependent enzyme in saliva that supports the growth and function of taste buds, helping restore normal taste sensation.

Zinc and Metabolic Syndrome

What is Metabolic Syndrome?

Metabolic syndrome is a group of conditions including obesity, insulin resistance, high blood pressure, and elevated cholesterol that increase the risk of heart disease and type 2 diabetes. [185] 

Effects of Zinc Supplementation

A study in children with metabolic syndrome found that zinc supplementation led to significant health improvements by: [186]

• Reducing insulin resistance
• Decreasing oxidative stress
• Lowering inflammation
• Reducing blood sugar levels
• Improving cholesterol levels
• Decreasing body mass index (BMI)

Zinc and Eye Health

• Age-Related Macular Degeneration: Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly and is believed to result from oxidative stress. Clinical studies have shown that zinc supplementation can slow the progression of AMD, possibly by preventing oxidative damage to the retina. [187] [188] [189] [190]
• Protection Against Diabetic Retinopathy: Zinc has been suggested to protect against diabetic retinopathy, a complication that can lead to blindness. It helps prevent retinal capillary cell death and abnormal new blood vessel growth (neovascularisation). This protective effect is attributed to zinc’s ability to reduce oxidative stress and inflammation by inhibiting NADPH oxidase and NF-κB, both of which are involved in the progression of diabetic retinopathy. [191]
• Night Blindness and Vitamin A: Night blindness is one of the earliest symptoms of vitamin A deficiency. A study found that zinc supplementation improved the effects of vitamin A in restoring night vision, particularly in pregnant women with low zinc levels. [192]

Zinc and Mitochondrial Function

• Study in rats: Zinc supplementation enhanced:
• Electron transfer system activity
• Oxidative phosphorylation in liver mitochondria
• Result: Increased ATP production (energy) in liver cells. [193]

Zinc and Body Odour

• Bromhidrosis (body odour): Caused by an overgrowth of bacteria in areas like the armpits, primarily: [194]
• Staphylococcus species
• Corynebacterium species
• Zinc’s role:
• Has strong antibacterial effects.
• Topical zinc treatments have been clinically shown to reduce armpit and foot odour. [18]

Zinc and Oral Health

• Zinc deficiency effects:
• Contributes to excessive plaque formation.
• Worsens gum inflammation in periodontal disease.
• Mechanism: increases production of the inflammatory molecule IL-1. [195] [196]
• Zinc-based interventions:
• Zinc-containing mouthwashes have been shown to reduce plaque growth effectively. [196]
• A study in children from low-income areas found that taking 15 mg of zinc daily for 10 weeks led to a significant reduction in dental plaque. [197]

Zinc and Cystic Fibrosis

• Cystic fibrosis (CF): A genetic disorder marked by:
• Breathing difficulties
• Pneumonia
• Poor weight gain
• Zinc supplementation benefits in CF patients (retrospective study): [198]
• Improved lung function
• Increased energy intake
• Reduced infection rates

Zinc and Arsenic Poisoning

• Context: Chronic arsenic poisoning can cause symptoms like:
• Melanosis (skin discoloration)
• Keratosis (skin thickening)
• Study finding: Supplementation with zinc combined with spirulina extract significantly reduced these symptoms. [199]

Zinc and Opioid Addiction

• Observation: Opioid users often show lower zinc levels in the body. [200] [201] [202]
• Animal studies:
• Zinc supplementation in mice and rats reduced the severity of morphine dependency.
• Zinc chelators (which remove zinc) increased the severity of withdrawal symptoms. [203] [204]
• Implication: Zinc may play a role in modulating opioid addiction and withdrawal.
• Potential application: Zinc supplementation could help reduce addiction risk or ease withdrawal symptoms in people prescribed opioids for chronic pain.
• Why zinc? It has pain-relieving effects and is generally low in toxicity, making it a potentially safe adjunct treatment. [204]

What Experts Say About Zinc?

• Source: Cochrane Collaboration (a respected global research network)
• Findings:
• Zinc supports recovery from acute respiratory infections.
• When taken regularly over several months, especially in schoolchildren:
• Lower incidence of colds
• Reduced absenteeism
• Less frequent use of antibiotics
• Implication: Zinc has preventive benefits against common colds and may reduce the need for medications.

• Studies from: France and Sweden
• Findings:
• Adequate zinc intake, especially in combination with selenium, is linked to a lower risk of prostate cancer.
• Zinc may also be beneficial as supportive therapy for existing prostate conditions.
• Implication: Zinc plays a role in prostate function and cancer prevention, likely due to its antioxidant and anti-inflammatory properties.