Zinc Deficiency Symptoms is an essential mineral, including prenatal and postnatal development. Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children, deficiency causes growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea. Enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency.
Zinc is involved in numerous aspects of cellular metabolism. It is required for the catalytic activity of approximately 100 enzymes and it plays a role in immune function, protein synthesis, wound healing, DNA synthesis, and cell division. Zinc also supports normal growth and development during pregnancy, childhood, and adolescence and is required for proper sense of taste and smell.
Deficiency Symptoms of Zinc
Skin, nails, and hair – Zinc deficiency may manifest as acne, eczema, xerosis (dry, scaling skin), seborrheic dermatitis, or alopecia (thin and sparse hair). There may also be impaired wound healing.
Mouth – Zinc deficiency can manifest as non-specific oral ulceration, stomatitis, or white tongue coating. Rarely it can cause angular cheilitis (sores at the corners of the mouth)and burning mouth syndrome.
Vision, smell, and taste – Severe zinc deficiency may disturb the sense of smell and taste. Night blindness may be a feature of severe zinc deficiency, although most reports of night blindness and abnormal dark adaptation in humans with zinc deficiency have occurred in combination with other nutritional deficiencies (e.g. vitamin A).
Immune system – Impaired immune function in people with zinc deficiency can lead to the development of respiratory, gastrointestinal, or other infections, e.g., pneumonia. The levels of inflammatory cytokines (e.g., IL-1β, IL-2, IL-6, and TNF-α) in blood plasma are affected by zinc deficiency and zinc supplementation produces a dose-dependent response in the level of these cytokines. During inflammation, there is an increased cellular demand for zinc and impaired zinc homeostasis from zinc deficiency is associated with chronic inflammation.
Diarrhea – Zinc deficiency contributes to an increased incidence and severity of diarrhea.
Appetite – Zinc deficiency may lead to loss of appetite or anorexia nervosa. The use of zinc in the treatment of anorexia has been advocated since 1979 by Bakan. At least 15 clinical trials have shown that zinc improved weight gain in anorexia. A 1994 trial showed that zinc doubled the rate of body mass increase in the treatment of anorexia nervosa. Deficiency of other nutrients such as tyrosine, tryptophan, and thiamine could contribute to this phenomenon of “malnutrition-induced malnutrition”.
Cognitive function and hedonic tone – Cognitive functions, such as learning and hedonic tone, are impaired with zinc deficiency. Moderate and more severe zinc deficiencies are associated with behavioral abnormalities, such as irritability, lethargy, and depression (e.g., involving anhedonia). Zinc supplementation produces a rapid and dramatic improvement in hedonic tone (i.e., a general level of happiness or pleasure) under these circumstances. Zinc supplementation has been reported to improve symptoms of ADHD and depression
Psychological disorders – Low plasma zinc levels have been alleged to be associated with many psychological disorders. Schizophrenics have been shown to have decreased brain zinc levels and supplementation as an adjuvant was shown to improve symptoms in one study. Evidence suggests that zinc deficiency could play a role in depression. Zinc supplementation may be an effective treatment in major depression. Low serum Zinc has been found in generalized anxiety disorder panic disorder and obsessive-compulsive disorder. People with Migraines have been shown to have low levels of Zinc and supplementation improved symptoms in a prospective study.
Growth – Zinc deficiency in children can cause delayed growth and has been claimed to be the cause of stunted growth in one-third of the world’s population.
During pregnancy – Zinc deficiency during pregnancy can negatively affect both the mother and fetus. Animal studies indicate that maternal zinc deficiency can upset both the sequencing and efficiency of the birth process. An increased incidence of difficult and prolonged labor, hemorrhage, uterine dystocia, and placental abruption has been documented in zinc-deficient animals. These effects may be mediated by the defective functioning of estrogen via the estrogen receptor, which contains a zinc finger protein.
Zinc deficiency can interfere with many metabolic processes when it occurs during infancy and childhood, a time of rapid growth and development when nutritional needs are high. Low maternal zinc status has been associated with less attention during the neonatal period and worse motor functioning. In some studies, supplementation has been associated with motor development in very low birth weight infants and more vigorous and functional activity in infants and toddlers.
Testosterone production – Zinc is required to produce testosterone. Thus, zinc deficiency can lead to reduced circulating testosterone, hypogonadism, and delayed puberty
- slower than expected growth
- the poor immune system function
- eye and skin lesions
- feeling lethargic
- funny-taste sensations
- hair loss
- poor wound healing
- unexplained weight loss
Recommended Intakes And Zinc Deficiency Symptoms
Intake recommendations for zinc and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences). DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and gender include the following
- Recommended Dietary Allowance (RDA) – Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
- Adequate Intake (AI) – Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA.
- Estimated Average Requirement (EAR) – Average daily level of intake estimated to meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals.
- Tolerable Upper Intake Level (UL) – Maximum daily intake unlikely to cause adverse health effects.
The current RDA for zinc is listed in Table 1. For infants aged 0 to 6 months, the FNB established an AI for zinc that is equivalent to the mean intake of zinc in healthy, breastfed infants.
|0–6 months||2 mg*||2 mg*|
|7–12 months||3 mg||3 mg|
|1–3 years||3 mg||3 mg|
|4–8 years||5 mg||5 mg|
|9–13 years||8 mg||8 mg|
|14–18 years||11 mg||9 mg||12 mg||13 mg|
|19+ years||11 mg||8 mg||11 mg||12 mg|
* Adequate Intake (AI)
Food Sources of Zinc
A wide variety of foods contain zinc. Oysters contain more zinc per serving than any other food, but red meat and poultry provide the majority of zinc in the American diet. Other good food sources include beans, nuts, certain types of seafood (such as crab and lobster), whole grains, fortified breakfast cereals, and dairy products.
Phytates—which are present in whole-grain bread, cereals, legumes, and other foods—bind zinc and inhibit its absorption. Thus, the bioavailability of zinc from grains and plant foods is lower than that from animal foods, although many grain- and plant-based foods are still good sources of zinc.
|Oysters, cooked, breaded and fried, 3 ounces||74.0||493|
|Beef chuck roast, braised, 3 ounces||7.0||47|
|Crab, Alaska king, cooked, 3 ounces||6.5||43|
|Beef patty, broiled, 3 ounces||5.3||35|
|Breakfast cereal, fortified with 25% of the DV for zinc, ¾ cup serving||3.8||25|
|Lobster, cooked, 3 ounces||3.4||23|
|Pork chop, loin, cooked, 3 ounces||2.9||19|
|Baked beans, canned, plain or vegetarian, ½ cup||2.9||19|
|Chicken, dark meat, cooked, 3 ounces||2.4||16|
|Yogurt, fruit, low fat, 8 ounces||1.7||11|
|Cashews, dry roasted, 1 ounce||1.6||11|
|Chickpeas, cooked, ½ cup||1.3||9|
|Cheese, Swiss, 1 ounce||1.2||8|
|Oatmeal, instant, plain, prepared with water, 1 packet||1.1||7|
|Milk, low-fat or nonfat, 1 cup||1.0||7|
|Almonds, dry roasted, 1 ounce||0.9||6|
|Kidney beans, cooked, ½ cup||0.9||6|
|Chicken breast, roasted, skin removed, ½ breast||0.9||6|
|Cheese, cheddar or mozzarella, 1 ounce||0.9||6|
|Peas, green, frozen, cooked, ½ cup||0.5||3|
|Flounder or sole, cooked, 3 ounces||0.3||2|
* DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents of products within the context of a total diet. The DV for zinc is 15 mg for adults and children age 4 and older. Food labels, however, are not required to list zinc content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.
The U.S. Department of Agriculture’s (USDA’s) Nutrient Database Web site lists the nutrient content of many foods and provides a comprehensive list of foods containing zinc arranged by nutrient content and by food name.
Health Benefit and Zinc Deficiency Symptoms
1. Zinc Boosts Immunity and Lowers Risk of Infection
Zinc is essential for the normal development and function of many immune cells
Because of the critical role, it plays in the immune system, even a mild deficiency can impair immune function and increase the risk of bacterial, viral, and parasitic infection.
In clinical states associated with immunodeficiency (e.g., sickle cell disease, human immunodeficiency virus (HIV) infection, Down syndrome, and in the elderly), zinc supplementation can restore natural killer cell activity, lymphocyte production, and resistance to infection
Studies in HIV patients with low blood zinc levels reveal that chronic supplementation is associated with lower opportunistic infections and a reduced risk of immunological failure. However, supplementation must be exercised with caution as excessive zinc may worsen disease symptoms.
People with acrodermatitis enteropathica (a genetic disorder affecting zinc absorption), experience high rates of infection. Zinc supplementation in therapeutic doses results in complete recovery.
Many studies showed that in infants and children in developing countries, zinc administration reduced the duration, severity, and incidence of acute and chronic diarrhea, acute lower respiratory tract infections, and malaria.
Similar beneficial effects were reported for other infectious diseases in humans including shigellosis, leprosy, tuberculosis, leishmaniasis, hepatitis C, and the common cold (by increasing Th1 cytokines)
On the other hand, excessive levels may suppress immunity. A study in healthy young men revealed that high doses of zinc reduced several immune functions, including activation of lymphocytes and phagocytosis of neutrophils
2. Zinc Acts as an Antioxidant
A study in the elderly showed that zinc supplementation was able to reduce fat peroxides in the blood.
In another study, it reduced DNA breakage in women. DNA breakage is commonly used as a parametric marker to assess the amount of injury induced by oxidative stress.
Zinc also restored superoxide radical scavengers to normal levels in the sperm of men with asthenospermia (poor sperm motility).
In addition, it protected against radiation-induced oxidative stress in mice
Zinc supplementation has also shown efficacy in treating Wilson’s disease, a disorder in which copper accumulates in tissues.
Zinc also helps prevent skin cell death from oxidative stress and bacterial toxins.
3. Zinc Controls Inflammation
Zinc inhibits the production of many inflammatory cytokines (by inhibiting
Studies in the elderly (who are often zinc deficient) show that it suppresses inflammation by lowering cytokines and other inflammatory markers.
Zinc also shows efficacy in a variety of inflammatory conditions including irritable bowel syndrome, acne, and asthma.
In an aged mouse model, supplementation resulted in fewer age-related increases in inflammatory markers.
4. Zinc May Prevent Transplant Rejection and Autoimmunity
Many studies reveal that zinc can suppress unwanted immune reactions (e.g., autoimmunity and transplant rejection) by inducing regulatory T-cells.
One study in healthy men found that zinc was able to reduce the rate of graft rejection while protecting the body from infections resulting from a suppressed immune system
In mouse models of multiple sclerosis and arthritis, it was able to improve disease symptoms by lowering inflammation, suppressing T-cell proliferation and increasing
In mixed lymphocyte cultures, zinc-induced regulatory T-cells, which helped reduce graft rejection by decreasing inflammatory cytokines and T-cell proliferation.
Similarly, zinc reduced heart transplant rejection in mouse models by preventing graft tissue death (by inhibiting caspase-3).
In rheumatoid arthritis patients, positive changes were observed regarding joint swelling, morning stiffness, and walking time after zinc therapy.
5. Zinc Combats Allergy and Asthma
In response to grass pollen, an allergen that is a major cause of allergic rhinitis in many parts of the world, zinc increased regulatory T-cells and decreased proliferation in peripheral blood mononuclear cells (PBMCs) isolated from allergic subjects
Low blood zinc levels are linked to more severe asthma symptoms in children
A study showed that zinc supplementation improved symptoms (e.g., cough, wheezing, and shortness of breath) in children with asthma
It was also able to reduce airway inflammation and hyperresponsiveness in mouse models of allergic inflammation and asthma
In allergen-sensitized mice, it was able to inhibit respiratory tract epithelial cell death (by inhibiting caspase-3) [R].
6. Zinc Enhances Wound Healing and Tissue Repair
Zinc enhanced the repair of skin ulcers in diabetic patients. Also, its deficiency is linked to delayed wound healing.
Studies in animals and humans show that zinc administration can speed up the healing process after surgery, burns, and other wounds.
When applied topically, zinc oxide improved the healing of excisional wounds in rats
7. Zinc Boosts Cognition and Protects Neurons
Zinc supplementation was able to enhance cognitive recovery in zinc deficient people who experienced an ischemic stroke.
A double-blind trial in children found that zinc supplementation resulted in superior neuropsychological performance, particularly attention and reasoning skills when compared with controls.
A randomized trial showed that zinc supplementation in infants and toddlers led to increased activity, mental development, and motor quality
In elderly Alzheimer’s disease patients, zinc therapy protected against cognitive decline by lowering free blood copper levels, which can be toxic to the brain.
Many animal studies show that in moderate concentrations, it is neuroprotective and helps preserve learning and memory function
In a mouse model of Alzheimer’s disease, zinc supplementation reduced pathological factors associated with progression of the disease (i.e., β-amyloid and tau protein loads) and improved mitochondrial function and brain-derived neurotrophic factor levels in the hippocampus.
Another study showed that maternal zinc supplementation enhanced spatial learning and memory in rat pups.
A study found that moderate doses (12 mg/kg) prolonged survival in a mouse model of ALS.
8. Zinc May Treat Psychiatric Disorders
A study in OCD patients showed that the addition of zinc to fluoxetine therapy was able to reduce symptoms (as assessed by the Yale-Brown Obsessive-Compulsive rating scale)
Since it can suppress glutamate release and transmission, it could have improved OCD symptoms.
In combination with methylphenidate (a CNS stimulant), zinc supplementation reduced hyperactivity and impulsivity in children with ADHD according to one study.
A study in schizophrenic men found that zinc in combination with risperidone improved many symptoms associated with the disorder (e.g., aggression, hallucinations, and delusions). This effect is in part attributed to its antioxidant and antidepressant properties.
9. Zinc May Prevent Autism
A study found that autistic individuals have lower levels of zinc compared to neurotypical (non-autistic) individuals. In the study, the severity of autistic symptoms (i.e., awareness, hyperactivity, receptive language, focus and attention, eye contact, tip-toeing, sound sensitivity, tactile sensitivity, and seizures) decreased after zinc and vitamin B6 treatment.
Studies found that prenatal zinc treatment prevented autistic-like behaviors (e.g., induced social deficits, repetitive behaviors, and cognitive inflexibility) in rat offspring, indicating a possible link between its deficiency and autism development
In a recent study, it was found to reverse brain cell changes in autism
- “Our work is showing that even the cells that carry genetic changes associated with autism can respond to zinc.”
- “Our research has focussed on the protein Shank3, which is localized at synapses in the brain and is associated with neurodevelopmental disorders such as autism and schizophrenia.”
- “Human patients with genetic changes in Shank3 show profound communication and behavioral deficits. In this study, we show that Shank3 is a key component of a zinc-sensitive signaling system that regulates how brain cells communicate.”
- “Intriguingly, autism-associated changes in the Shank3 gene impair brain cell communication,” says Dr. Montgomery. “These genetic changes in Shank3 do not alter its ability to respond to zinc”.
- “As a result, we have shown that zinc can increase brain cell communication that was previously weakened by autism-associated changes in Shank3”.
- “Disruption of how zinc is regulated in the body may not only impair how synapses work in the brain but may lead to cognitive and behavioral abnormalities seen in patients with psychiatric disorders.”
- “Together with our results, the data suggests that environmental/dietary factors such as changes in zinc levels could alter this protein’s signaling system and reduce its ability to regulate the nerve cell function in the brain,” she says.
10. Zinc Reduces Stress and Improves Mood
Zinc supplementation has shown efficacy in treating mood disorders (e.g., depression and anxiety) clinically and in animal models
It also increases brain-derived neurotrophic factor (BDNF) levels, which are low in people with depression.
A study found that zinc therapy was able to improve overall mood in overweight subjects, likely through increasing BDNF levels
11. Zinc Controls Cell Death
Both high and low intracellular concentrations of zinc trigger apoptosis (cell death) in many cell types .
12. Zinc May Prevent Cancer
Zinc deficiency substantially increases the risk of cancer in the mouth, esophagus, and stomach. Digestive tract tissues are more susceptible because of their high exposure to outside toxins
Low blood zinc levels are also associated with head, neck, lung, gall bladder, prostate, and ovarian cancers. Restoring normal levels can improve natural killer cell function, which is essential for killing tumor cells.
It can also block tumor growth by reducing glucose uptake, preventing the growth of new blood vessels, and inducing cell death in cancer cells from animals and humans.
13. Zinc is Antimicrobial
In high doses, zinc inhibits the growth of several bacterial species, particularly gram-positive organisms.
Zinc showed antibacterial activity against aerobic and anaerobic organisms in root canals
It also inhibited the attachment and growth of Staphylococcus aureus (S. aureus) in skin tissue.
Zinc also exhibits antimicrobial effects against the common wound flora in rats.
14. Zinc May Treat Epilepsy and Prevent Seizures
Several studies reported a marked decrease in blood zinc levels of patients with intractable epilepsy.
A study in epileptic children revealed that zinc therapy significantly reduced the frequency of seizures in 31% of the treated children.
Zinc supplementation was also able to prolong the latency (a period between seizures) of febrile (fever) seizures in rats.
15. Zinc Promotes Growth
In a number of studies, zinc supplementation produced significant beneficial effects on both height and weight measures of children, especially in underweight children and children suffering from stunted growth
An analysis of studies of growth in children revealed that a dose of 10 mg of zinc daily for 24 weeks led to a net increase of around 0.37 cm (in height) in zinc-supplemented children compared to children treated with a placebo.
It also increases muscle mass in children.
16. Zinc Protects the Gut
Zinc supplementation has a protective effect on the gut lining of animal models and humans in a variety of gastrointestinal diseases (e.g., inflammatory bowel disease, cancer, alcohol toxicity, and colitis).
It stabilized the gut mucosa and reduced stomach and small intestinal injuries by enhancing gut repair processes in rats and mice
Zinc also protected the intestinal mucosa from alcohol-induced damage in rats and mice It can prevent gut leakiness, which may reduce the risk of developing inflammatory bowel disease
A study in patients with dyspepsia (indigestion) found that inflammation in H.pylori-induced stomach cancer was negatively correlated with zinc concentration, indicating that zinc may reduce the risk of stomach cancer by suppressing stomach inflammation
17. Zinc Improves Sleep Quality
Women and children with higher blood zinc concentrations have better sleep quality.
A study in infants revealed that zinc supplementation was able to prolong sleep duration
18. Zinc Stimulates Appetite and May Treat Anorexia
One of the earliest signs of a zinc deficiency is a loss of appetite
A study in rats showed that oral zinc supplementation was able to rapidly stimulate food intake (by increasing orexin and neuropeptide Y)
Clinical studies in patients with anorexia nervosa (AN) show a significant association between the disease and low blood zinc levels
Many studies with oral zinc supplementation reported an increase in weight gain, muscle mass, appetite, taste sensitivity, and food intake in AN patients
19. Zinc Boosts Skin Health
Zinc has been shown to be beneficial for a variety of skin conditions (e.g., acne, warts, rosacea, eczema, psoriasis, melasma, and dandruff).
In people with acne vulgaris, zinc-supplemented groups (with zinc taken orally) showed a significant improvement in symptoms when compared with placebo groups
Clinical trials in patients with viral warts resulted in a complete clearance of warts for a majority of zinc-treated individuals
Zinc exhibits similar efficacy in treating Herpes genitalis (genital warts caused by Herpes simplex virus (HSV) 1 and 2).
A study in people with rosacea (a chronic inflammatory disease characterized by flushing, small blood vessels, and red bumps on the face) showed that oral zinc was able to reduce disease symptoms
Zinc supplementation exhibits similar efficacy in treating other inflammatory skin disorders such as psoriasis and eczema, likely owing to zinc’s anti-inflammatory and antioxidant properties
Zinc may also treat seborrhoeic dermatitis (dandruff). Studies show that shampoos containing zinc can significantly reduce the scaling and inflammation associated with dandruff
Melasma is a skin pigmentary disorder that causes brown skin discoloration. Zinc treatment was able to reduce the severity of this disorder in affected patients with minimal side effects
Zinc also protects against sun damage to the skin, which can cause skin aging and cancer. A study in humans found that oral zinc supplementation was more superior than titanium oxide in providing protection against ultraviolet (UV) irradiation
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20. Zinc May Prevent Hair Loss
In a clinical study, topical zinc was able to improve hair growth in bald men. It was hypothesized that zinc’s antimicrobial, anti-inflammatory, antioxidant, and anti-androgenic effects on the scalp were potentially involved in the increase of hair density
Another study in women with the polycystic ovarian syndrome (PCOS) showed that zinc supplementation had beneficial effects on a number of symptoms, including alopecia (hair loss)
Zinc treatment also reversed hair loss in patients who underwent vertical gastroplasty (stomach stapling), a surgical operation that can result in zinc deficiency.
21. Zinc May Improve Symptoms of Kidney Disease
Restoring zinc levels in chronic kidney disease patients on hemodialysis can improve overall kidney function and reduce many complications associated with the disease (e.g., heart disease, anemia, infections, and sexual dysfunction) by reducing inflammation, oxidative stress, and cholesterol, as well as by enhancing hemoglobin, sex hormones (i.e., testosterone and LH), and immune function
22. Zinc Protects the Liver
Zinc supplementation in animal models of alcoholic liver disease (ALD) protected the liver by blocking most mechanisms of liver injury (i.e., gut leakage, endotoxemia, oxidative stress, excess inflammatory cytokine production, and liver cell death)
In patients with non-alcoholic liver cirrhosis, supplemental zinc improved liver function and prevented excessive copper accumulation, which can damage the liver
Zinc also improved the outcome of patients with hepatitis C which, if left untreated, can lead to liver scarring.
23. Zinc Strengthens Bones
Studies have found that zinc can increase bone density and strength by enhancing bone formation and preventing bone loss
In mouse osteoblast (bone-forming) cells, zinc treatment stimulated bone forming activity
Another study revealed that zinc supplementation increased bone formation markers (i.e., ALP, BAPE, and BAP-M) in healthy men
Zinc was also able to suppress bone breakdown activity in mouse bone marrow cultures by inhibiting bone breakdown markers (e.g., parathyroid hormone and PGE2)
Because of its bone-strengthening effects, zinc was found to protect against many bone-related complications in animals and humans.
24. Zinc Prevents Heart Disease
Studies have shown that zinc levels are often low in people with atherosclerosis (hardening of the arteries), heart disease, chest pain, and heat stroke
One study found that a higher rate of cardiac failure was associated with zinc deficiency.
Other studies revealed that high doses of zinc were able to prevent and treat angina (chest pain) in patients with atherosclerosis
Supplemental zinc was also able to protect the heart from stroke-related injuries in rats and mice
25. Zinc Increases Insulin Sensitivity and May Prevent Diabetes and its Complications
Zinc ions can bind to insulin receptors and activate insulin signaling pathways
By mimicking insulin, zinc reduces excessive insulin secretion by pancreatic cells, which helps protect the pancreatic tissue from damage
Zinc also improves the solubility of insulin in pancreatic cells and enhances insulin binding to its receptor
Because of zinc’s essential role in the processing, storage, and secretion of insulin, a deficiency can lead to increased insulin resistance
A study found that prediabetic patients were more likely to be zinc deficient
Other studies found high percentages of zinc deficiency in type 2 diabetes patients
Studies in women report that higher dietary zinc intakes can reduce the risk of developing type 2 diabetes
Several studies found that zinc supplementation reduced fasting blood sugar levels and improved insulin sensitivity in diabetic animal models and humans
Zinc also decreased the severity of diabetic neuropathy (nerve pain), oxidative stress, and cholesterol/triglyceride levels in type 2 diabetic patients
26. Zinc Aids in Weight Loss
Leptin is a hormone that plays a role in appetite and weight control. Zinc restriction can lead to reduced leptin production from fat cells in rats and humans
Restoration of zinc levels in men with a marginal zinc deficiency led to an increase in blood leptin levels (possibly through increased IL-2 and TNF-alpha)
27. Zinc is Radioprotective
Zinc has been shown to protect against radiation-induced toxicity in mice and bone marrow precursor cells.
It reduced oxidative stress (as measured by MDA levels) and stabilized antioxidant enzymes (i.e., GR, Cu/Zn SOD, and catalase) in the red blood cells of rats after radioactive iodine (131I) exposure
Zinc treatment was also able to protect the precursor sperm cells of mice from radiation-induced cell death
28. Zinc Reduces Body Odor
Bromhidrosis (body odor) is usually associated with increased bacterial flora in the armpit region, mainly consisting of Staphylococcus and Corynebacterium species
Because of its antibacterial action, topical zinc has shown efficacy in reducing armpit and foot odor in clinical studies
29. Zinc Improves Oral Health
Zinc deficiency can lead to excessive plaque formation and worsen the inflammatory process in gum disease (from an increased production of IL-1)
Zinc-based mouthwashes were found to be effective in reducing plaque growth
Similarly, a study in children from low-income areas found that a daily intake of 15 mg of zinc for ten weeks was associated with reduced plaque formation on the teeth
30. Zinc Enhances Male Fertility and Reproductive Health
Seminal zinc concentration is positively correlated with sperm count, motility, and viability
This is likely because of zinc’s role in stabilizing the cellular membranes and DNA (by reducing oxidative damage) of sperm cells and enhancing spermatogenesis (formation of new sperm cells)
Low to moderate doses (12 -120 mg/kg) of zinc intake appeared to enhance reproductive function in rats
Zinc is highly concentrated in the prostate and testes and is involved in the synthesis of testosterone
In infertile men (with low blood testosterone), supplemental zinc led to an increase in sperm count, testosterone, dihydrotestosterone (DHT), and fertility.
Zinc’s testosterone boosting effects may aid in increasing the libido and sexual performance of men with erectile dysfunction (who are often testosterone deficient)
Zinc can also reduce oxidative damage to the testicles. In rats, zinc was able to preserve testicular function (as measured by testicular weight, sperm concentration, and testosterone levels) in response to oxidative stress induced by cigarette smoke
31. Zinc Combats Fatigue
Low concentrations of zinc in the blood are associated with many symptoms of chronic fatigue syndrome (e.g., fatigue, depression, and concentration difficulties). One study found that blood zinc levels were significantly lower in chronic fatigue syndrome (CFS) patients than in normal controls and that symptom severity was negatively correlated with blood zinc levels.
The study concluded that zinc may be effective in attenuating CFS symptoms because of its antioxidant and anti-inflammatory properties.
Gut inflammation (caused by a leaky gut) is common in people with CFS
A study found that treating leaky gut with a mixture of anti-inflammatory and antioxidant substances including zinc in CFS patients resulted in a significant improvement of symptoms
32. Zinc Controls Blood Clotting
Human studies show that zinc is involved in regulating pro-thrombotic (clot forming) and anti-thrombotic (clot-preventing) factors derived from platelets and the blood vessel lumen
Hyperzincemia (high levels of zinc in the blood) can cause blood clotting while hypozincemia (low levels of zinc in the blood) leads to prolonged blood clotting times. Both conditions cause impairments in platelet aggregation and abnormal bleeding
One study revealed that restoring zinc levels in zinc-deficient men led to normalized platelet aggregation and blood clotting time
33. Zinc Improves Pregnancy Outcome
Low blood zinc levels are associated with pregnancy complications (e.g., spontaneous abortion, pre-eclampsia, extended pregnancy, preterm birth, and abnormal fetal development).
Studies have shown that maternal zinc supplementation (in zinc deficient or underweight women) can reduce the risk of preterm birth and protect against fetal damage from alcohol exposure.
A study found that Indian mothers receiving supplemental zinc had longer gestational periods (pregnancy times) and babies with healthier weights
Another study in pregnant women (with low blood zinc levels) found that zinc supplementation (25 mg/day) during the second half of pregnancy significantly increased infant birth weights and head circumferences
It is proposed that these beneficial effects are a result of its ability to inhibit embryonic cell death, increase growth factors (e.g., IGF, PDGF, and FGF), and reduce oxidative damage, all of which help promote the healthy fetal development
34. Zinc is Beneficial for Women’s Health
Zinc deficiency is associated with hormonal imbalances that can lead to ovarian function problems, menstruation irregularities, and infertility
Several studies have found that that oral zinc administration (in combination with mefenamic acid and alone) was able to reduce the severity and duration of menstrual pain in women
These effects are likely due to zinc’s inhibition of prostaglandin metabolism in the uterus, which leads to decreased painful cramping in the lower abdomen
In women with the polycystic ovarian syndrome (PCOS), insulin resistance can cause an increased production of androgen hormones (e.g., testosterone and DHEA), which can lead to balding, body hair growth, irregular periods and infertility
Studies have found that zinc supplementation in women with PCOS can reduce insulin levels and improve disease symptoms (e.g., body hair growth and balding)
Women with endometriosis (a condition where the tissue inside the uterus grows outside of the uterus) exhibit low blood zinc levels
One study reported that an intake of antioxidants (i.e., vitamin C, vitamin E, selenium, and zinc) was inversely correlated with the severity of endometriosis progression in women, indicating that zinc may slow the development of this disorder
35. Zinc Alleviates Pain
Zinc has been shown to have pain relieving properties in a number of animal studies
In rats with sciatic nerve injury, injection of zinc chloride significantly relieved thermal hyperalgesia (heightened sensitivity to pain) in a dose-dependent manner
Another study showed that zinc salts were able to suppress pain in mice exposed to a series of painful stimuli (e.g., heat and irritant chemicals)
In patients with a chronic liver disease, zinc reduced the frequency and severity of muscle cramp pain
It is proposed that zinc relieves pain in part by binding to the NMDA receptor (as an antagonist), which is involved in initiating pain pathways
36. Zinc May Reduce Opioid Addiction
Opioid users exhibit lower levels of zinc
Studies in mice and rats found that zinc reduced the dependence intensity of morphine (an opioid), while zinc chelators intensified withdrawal symptoms.
Based on these results, a literature review article suggested that zinc supplementation may be beneficial in reducing the risk of addiction in humans taking opioids for chronic pain because of zinc’s pain-relieving effects and low toxicity
37. Zinc Increases Taste Sensitivity
Zinc deficiency is associated with decreased taste acuity (sensitivity)
This may be because Justin (or carbonic anhydrase VI), a zinc-dependent enzyme, is not as active when salivary concentrations of zinc are low
One study found that zinc supplementation led to increased taste acuity (as assessed by recognition thresholds for salt) in Indian adolescent girls (who are often zinc deficient).
38. Zinc May Prevent Blindness
Age-related macular degeneration, a major cause of blindness in the elderly, is believed to be caused by oxidative stress. Clinical studies have found that zinc supplementation can slow the progression of the disease, possibly by preventing oxidative damage to the retina
It has been suggested that zinc may protect against diabetic retinopathy (which can lead to blindness) by preventing retinal capillary cell death and neovascularization (growth of new blood vessels).
This is because of zinc’s ability to reduce oxidative stress and inflammation (through inhibition of NADPH oxidase and NF-κB), which is implicated in the progression of diabetic retinopathy
Night blindness is one of the earliest symptoms of vitamin A deficiency. A study found that zinc was able to enhance the effect of vitamin A in restoring the night vision of pregnant women (who had low zinc levels)
39.Zinc Treats Hearing Disorders
Zinc deficiency is linked to impaired hearing in mice and rats, which can be cured with zinc supplementation
This is likely a result of zinc’s protective effects (by increasing SOD) against toxins in ear structures (e.g., cochlea and vestibule)
People with tinnitus (ringing in the ears) have lower levels of zinc in the blood
One study has reported that zinc supplementation (50 mg/day) for two months was able to reduce the severity of tinnitus in 82% of patients
In another study, it was found that the addition of zinc to oral corticosterone was associated with a greater improvement in symptoms in people with a sudden sensorineural hearing loss (sudden deafness from unknown reasons) than by corticosterone alone
Otitis media (OM) is an infection of the middle ear. One study found zinc supplementation was able to significantly reduce the rate of otitis media in healthy children from low-income areas
40. Zinc May Prolong Lifespan
Oxidative stress is thought to accelerate the aging process
Zinc is a key component of Cu/Zn superoxide dismutase (Cu/Zn-SOD), a powerful enzyme that neutralizes superoxide radicals
A study found that worms (i.e. S. cerevisiae) and mice genetically manipulated to express high levels of SOD had longer lifespans
Mutations in the SOD gene are associated with many age-related diseases (e.g., ALS, Parkinson’s disease, Alzheimer’s disease, and cancer)
Inflammation is also involved in the process of aging
Zinc supplementation in the elderly was found to decrease inflammation, oxidative stress, and the rate of infection.
Thus, due to its antioxidant and anti-inflammatory properties, zinc may promote longevity, particularly in the elderly (who are often zinc deficient).
41. Zinc Promotes Thyroid Function
In animal and human studies, zinc deficiency is associated with a decline in thyroid function (due to low levels of triiodothyronine (T3) and free thyroxine(FT4) in the blood)
Supplementary zinc has been shown to have favorable effects on thyroid function in humans
In disabled hypothyroid patients under anticonvulsant therapy (with mild to moderate zinc deficiency), zinc supplementation was able to normalize thyroid hormone levels in the blood (i.e., T3 and FT3) and restore thyroid function
In a case study of two college females, zinc intake increased thyroid hormone levels (i.e., T3 and T4) and resting metabolic rate
Zinc supplementation was also to reverse the damaging effects of computer monitor-emitted radiation on the thyroid hormone levels of computer workers.
42. Zinc May Alleviate Cystic Fibrosis
Cystic fibrosis is a genetic disorder that can cause breathing problems, lung infection, and an inability to gain weight. A retrospective study in cystic fibrosis patients found that zinc supplementation was able to improve lung function, energy intake, and decrease the rate of infection
43. Zinc May Enhance Athletic Performance
A study in wrestlers found that heavy exercise can significantly deplete thyroid hormones and testosterone levels, which can lead to exhaustion. However, zinc supplementation was able to prevent this loss, indicating that intake (in physiological doses) may benefit athletic performance.
Another study in sedentary men showed similar results
44. Zinc May Reduce Chemotherapy Side Effects
Mucositis (ulceration of mucous membranes) is a common side effect of chemotherapy and radiotherapy
Studies in patients who underwent chemotherapy and radiotherapy found that zinc supplementation was able to reduce the severity of oral mucositis
Dysgeusia (distortion of taste) and dysosmia (distortion of smell) can also occur during chemotherapy
A study found that a daily intake of 100 mg of zinc for 4-6 months improved dysgeusia and dysosmia symptoms in patients with carbonic anhydrase VI (Justin) deficiency
This effect is because it is known to stimulate the production of carbonic anhydrase VI, an enzyme in the saliva that is involved in taste bud growth
45. Zinc Reduces the Risk of Metabolic Syndrome
Metabolic syndrome is a cluster of conditions (e.g., obesity, insulin resistance, high blood pressure, and high cholesterol) that can lead to an increased risk of developing heart disease and type 2 diabetes
A study in children with metabolic syndrome found that zinc supplementation decreased insulin resistance, oxidative stress, inflammation, blood sugar, cholesterol, and body mass index
46. Zinc Improves Mitochondrial Function
A study in rats found that zinc intake enhanced the electron transport system and oxidative phosphorylation in the liver mitochondria, which increased energy output (ATP) in liver cells
47. Zinc May Treat Arsenic Poisoning
A study in patients with chronic arsenic poisoning showed that zinc in combination with spirulina extract was effective in reducing symptoms (i.e., melanosis and keratosis)