Zinc and zinc supplments

Zinc is an essential mineral that plays a critical role in many biological processes in the body. It is required for the proper function of more than 300 enzymes, which are proteins that facilitate chemical reactions in the body. Zinc is also involved in the regulation of gene expression, as it modulates the activity of more than 2,000 transcription factors, which are proteins that control the expression of genes.

One of the key roles of zinc is in supporting the immune system. Zinc is involved in the production and function of immune cells, and a deficiency in zinc can increase the risk of infections and other immune-related disorders. Zinc also plays a role in wound healing and tissue repair, as it is required for the synthesis of DNA, RNA, and proteins that are necessary for these processes.

Zinc is also important for growth and development, particularly in children. It is required for the proper growth and development of the reproductive system, and a deficiency in zinc can cause growth retardation and delayed sexual maturation.

In addition to these roles, zinc is also involved in many other biological processes, including protein synthesis, carbohydrate metabolism, and antioxidant defense. It is an important component of many enzymes and proteins, and its absence can lead to a wide range of health problems.

Because the body cannot produce zinc on its own, it must be obtained through the diet or through supplements. Zinc is found in a variety of foods, including meat, seafood, nuts, seeds, and whole grains. While zinc deficiency is not common in developed countries, it can occur in individuals who do not consume enough zinc-rich foods or who have conditions that impair zinc absorption or utilization. Therefore, ensuring adequate zinc intake is essential for maintaining overall health and well-being.

Zinc – Summary

Zinc is an essential micronutrient present in foods and available through supplements that participates in numerous biological processes and modulates the activity of more than 300 enzymes and 2,000 transcription factors. We need to have enough zinc in our system to function properly.

History of Zinc

Zinc has been used by humans for thousands of years, and its history can be traced back to ancient times. The use of zinc was first documented in ancient India, where it was used to create brass, a copper-zinc alloy that was prized for its durability and beauty.

Zinc has been used for weapons manufacturing by ancient Greeks and Romans however in the 20th century, zinc was recognized as an essential nutrient for human health, and its role in many biological processes was studied. It was also found to have antimicrobial properties, and it has been used in the treatment of a variety of infections.

Zinc as a micronutrient

Dr. Ananda S. Prasad was one of the first scientists to recognize the importance of zinc as a micronutrient for human health. In the 1960s, Prasad was working as a physician in the Middle East, where he encountered patients with a rare genetic disorder called acrodermatitis enteropathica, which causes severe zinc deficiency and a range of symptoms, including skin rashes and gastrointestinal problems.

Prasad was intrigued by this disorder and began to study it further. He conducted experiments in which he gave zinc supplements to patients with acrodermatitis enteropathica, and he found that their symptoms improved dramatically. This led him to hypothesize that zinc might be an essential nutrient for human health, and he began to study the role of zinc in other medical problems.

Over the years, Prasad and his colleagues conducted numerous studies on zinc and its effects on human health. They found that zinc was important for immune function, wound healing, and growth and development, among other things. They also found that zinc deficiency was common in certain populations, such as pregnant women, infants, and the elderly.

Prasad’s work helped to establish zinc as an important micronutrient for human health, and his research has had a major impact on the prevention and treatment of medical problems. Today, zinc is recognized as an essential nutrient, and it is included in many multivitamin and mineral supplements. It is also used as a treatment for a variety of conditions, including diarrhea, respiratory infections, and skin conditions.

Zinc deficiency

Zinc deficiency is a global health issue, and it is estimated that up to 2 billion people worldwide may have inadequate zinc intake. The prevalence of zinc deficiency varies widely by region and population, but it is generally more common in developing countries where diets are less diverse and food insecurity is more prevalent.

In Europe and North America, zinc deficiency is less common, but it still occurs in certain populations, such as people who follow restrictive diets, individuals with gastrointestinal disorders that affect zinc absorption, and those who have had bariatric surgery. Older adults may also be at risk of zinc deficiency due to reduced dietary intake and impaired absorption.

Testing for zinc deficiency can be challenging, as there is no single, reliable method for measuring zinc status in the body. Blood tests for zinc levels are often used, but they may not be accurate, as only a small fraction of the body’s zinc is found in the blood. Hair analysis is another method that has been used to assess zinc status, but it is not widely accepted as a reliable indicator of zinc status.

A more comprehensive approach to assessing zinc status involves evaluating dietary intake, clinical symptoms, and laboratory measurements. Symptoms of zinc deficiency can include poor wound healing, hair loss, skin rashes, and impaired immune function. Laboratory measurements can include blood tests for zinc levels, as well as tests for zinc-related enzymes and proteins.

Dietary sources of zinc

Here are some common dietary sources of zinc, ranked by their zinc content per serving:

Oysters – 6 medium oysters provide about 32 mg of zinc
Beef – 3 oz of beef chuck roast provide about 7 mg of zinc
Pork – 3 oz of pork shoulder provide about 2.9 mg of zinc
Chicken – 3 oz of chicken thigh provide about 1 mg of zinc
Lentils – 1 cup of cooked lentils provide about 1.3 mg of zinc
Hemp seeds – 3 tbsp of hemp seeds provide about 2.8 mg of zinc
Cashews – 1 oz of cashews provide about 1.6 mg of zinc
Quinoa – 1 cup of cooked quinoa provides about 2 mg of zinc
Pumpkin seeds – 1 oz of pumpkin seeds provides about 2.5 mg of zinc
Yogurt – 1 cup of plain, low-fat yogurt provides about 1.6 mg of zinc

The bioavailability, or the extent to which the body can absorb and utilize zinc from different food sources, can vary. Animal-based sources of zinc, such as oysters and meat, are generally more bioavailable than plant-based sources, such as legumes and grains. The absorption of zinc from plant-based sources can be reduced by certain compounds, such as phytates and fiber, which can bind to zinc and inhibit its absorption.

Absorption of zinc from the diet depends on several factors, including the type of food consumed, the individual’s overall health and nutritional status, and the presence of other nutrients that can enhance or inhibit zinc absorption. It is generally estimated that the absorption of zinc from the diet ranges from around 10% to 40%, with higher absorption rates observed for animal-based sources and lower absorption rates observed for plant-based sources.

Dietary recommendations for zinc

The Recommended Dietary Allowance (RDA) for zinc intake varies depending on age, gender, and other factors. Here are the current RDAs for zinc intake in the United States, as established by the National Institutes of Health:

Infants 0-6 months: 2 mg/day
Infants 7-12 months: 3 mg/day
Children 1-3 years: 3 mg/day
Children 4-8 years: 5 mg/day
Children 9-13 years: 8 mg/day
Adolescents 14-18 years (boys): 11 mg/day
Adolescents 14-18 years (girls): 9 mg/day
Adults (men): 11 mg/day
Adults (women): 8 mg/day
Pregnant women: 11-12 mg/day
Breastfeeding women: 12-13 mg/day

It’s important to note that certain populations, such as vegetarians and vegans, may need to consume higher amounts of zinc to ensure adequate intake, as plant-based sources of zinc are generally less bioavailable than animal-based sources.

While it is possible to consume too much zinc, the Tolerable Upper Intake Level (UL) for zinc is relatively high. The UL for zinc intake in the United States is 40 mg/day for adults, and excessive intake of zinc can cause adverse effects, such as nausea, vomiting, and diarrhea. Chronic excessive intake of zinc can also interfere with copper absorption and cause copper deficiency.

Zinc deficiency

The symptoms of zinc deficiency can vary depending on the severity and duration of the deficiency. Some of the most common symptoms of zinc deficiency include:

Poor immune function, leading to increased risk of infections
Delayed wound healing and impaired skin health
Hair loss and brittle nails
Loss of appetite and impaired taste and smell
Delayed growth and development in children
Impaired cognitive function and learning ability
Reproductive problems, such as infertility and low sperm count

It’s important to note that many of these symptoms can be caused by other factors as well, and a diagnosis of zinc deficiency should be confirmed through laboratory testing.

Zinc deficiency can be difficult to detect, as there is no single, reliable method for measuring zinc status in the body. Laboratory tests, such as blood tests for zinc levels, can provide some information, but they may not be accurate, as only a small fraction of the body’s zinc is found in the blood. Symptoms of zinc deficiency may be a better indicator of low zinc levels, and healthcare professionals may also consider dietary intake and other factors when evaluating zinc status.

Genetic factors in zinc deficiency

There several known genetic factors can affect an individual’s risk of developing a zinc deficiency. Here are some examples:

SLC39A4 gene mutations: Mutations in the SLC39A4 gene, which encodes a zinc transporter, can lead to a rare autosomal recessive disorder called acrodermatitis enteropathica (AE). Individuals with AE are unable to absorb zinc from food, leading to zinc deficiency and symptoms such as skin lesions, diarrhea, and hair loss. Studies have identified various mutations in the SLC39A4 gene in individuals with AE (1, 2).
SLC30A2 gene mutations: Mutations in the SLC30A2 gene, which encodes a zinc transporter, can lead to a rare autosomal recessive disorder called zinc deficiency 2 (ZINC2). Individuals with ZINC2 have low levels of zinc in their blood and tissues, leading to symptoms such as growth retardation, immune dysfunction, and neurological problems. Studies have identified various mutations in the SLC30A2 gene in individuals with ZINC2 (3, 4).
ZnT8 gene polymorphisms: Polymorphisms in the SLC30A8 gene, which encodes a zinc transporter, have been associated with an increased risk of developing type 2 diabetes. Studies have found that individuals with certain variants of the SLC30A8 gene have lower zinc levels and impaired insulin secretion compared to individuals without the variants (5, 6).
Other genetic factors: Other genes involved in zinc metabolism and function may also influence an individual’s risk of developing zinc deficiency. For example, mutations in the metallothionein gene, which encodes a protein that binds and regulates zinc levels, have been associated with impaired zinc metabolism and increased risk of zinc deficiency (7, 8).

While genetic factors can play a role in the development of zinc deficiency, they are relatively rare compared to other factors, such as inadequate dietary intake or impaired absorption due to certain medical conditions.

Medical conditions that impact zinc absorption

Besides genetic factors that can impact zinc absorption, there are also known medical conditions that are associated with reduced zinc intake which can lead to problems.

Gastrointestinal disorders: Conditions that affect the gastrointestinal tract, such as Crohn’s disease, ulcerative colitis, and celiac disease, can impair zinc absorption due to inflammation, damage to the intestinal lining, and malabsorption of nutrients. Several studies have found that individuals with inflammatory bowel disease (IBD) have lower zinc levels and a higher risk of zinc deficiency compared to healthy individuals (11, 12).
Bariatric surgery: Procedures such as gastric bypass and sleeve gastrectomy can reduce the size of the stomach and alter the normal digestive process, leading to reduced absorption of zinc and other nutrients. Several studies have found that individuals who have undergone bariatric surgery have an increased risk of zinc deficiency and may require higher doses of zinc supplements (13, 44).
Alcoholism: Chronic alcohol consumption can interfere with zinc absorption and utilization, leading to lower zinc levels and an increased risk of zinc deficiency. Studies have found that individuals with alcoholism have lower zinc levels and a higher risk of zinc deficiency compared to non-drinkers (15, 16).
Diabetes: Studies have found that individuals with type 2 diabetes may have impaired zinc metabolism and a higher risk of zinc deficiency. Zinc supplementation has been shown to improve glucose control and insulin sensitivity in individuals with diabetes (17, 18).
Aging: Older adults may be at risk of zinc deficiency due to reduced dietary intake, impaired absorption, and changes in zinc metabolism. Studies have found that older adults have lower zinc levels and a higher risk of zinc deficiency compared to younger adults (19, 20).

While genetic and medical conditions, as well as aging, are notable factors that can play a role in the development of zinc deficiency, they are relatively rare compared to other factors, such as inadequate dietary intake or lifestyle.

Populations at risk from low zinc-intake

Adequate zinc nutrition is essential for adequate growth, immunocompetent, and neurobehavioral development, but limited information on population zinc status hinders the expansion of interventions to control zinc deficiency. An estimated 17.3% of the world’s population is at risk of inadequate zinc intake(9).

Zinc deficiency could be linked to foods available in different regions and inadequate dietary zinc intake may be fairly common, particularly in Sub-Saharan Africa and South Asia, allow inter-country comparisons regarding the relative likelihood of zinc deficiency as a public health problem.

Generally, dietary zinc intake among people living in the United States is thought to be at or above the RDA for all age groups. People who follow vegetarian or vegan diets, consume alcohol or have been diagnosed with certain diseases such as sickle cell anemia or gastrointestinal diseases may require higher intake than healthy people or those who consume meat. But there are some population groups at particular risk of low zinc levels.

The elderly: Zinc deficiency is more prevalent in older adults, especially those over the age of 60. This may be due to decreased dietary intake, impaired absorption, increased excretion, and/or altered metabolism. A review of studies found that up to 30% of older adults may be at risk for zinc deficiency, particularly those in long-term care facilities (21). A study in Poland found that serum zinc levels were significantly lower in older adults compared to younger adults (22).
Pregnant women: Adequate zinc intake is critical for fetal growth and development, as well as maternal health. Low maternal zinc status has been associated with an increased risk of preterm birth, low birth weight, and neural tube defects (23). A systematic review and meta-analysis of studies found that pregnant women in low- and middle-income countries had a higher prevalence of zinc deficiency compared to pregnant women in high-income countries (24).
Young children: Zinc deficiency is common among young children, especially in developing countries. It can lead to growth retardation, impaired immune function, and other health problems. A study in rural Bangladesh found that 42% of children under the age of 5 had low serum zinc levels (25). A randomized controlled trial in India found that zinc supplementation reduced the incidence of diarrhea and pneumonia in children under the age of 5 (26).

Overall, adequate zinc intake is important for all age groups, but certain populations, such as the elderly, pregnant women, and young children, may be at greater risk of deficiency. It’s important to ensure that these groups are getting enough zinc through a balanced diet or supplementation, as needed.

How to measure zinc levels

Zinc levels can be measured in different biological samples, including blood, serum, plasma, urine, hair, and nails. The most common methods for measuring zinc levels are:

Serum or plasma zinc: These tests measure the amount of zinc in the liquid portion of the blood. They are considered the most accurate and reliable indicators of zinc status (27).
Urine zinc: This test measures the amount of zinc excreted in the urine. It can be used to estimate recent zinc intake, but is not as reliable as serum or plasma zinc tests (27).
Hair or nail zinc: These tests measure the amount of zinc in hair or nail samples. They can provide information about long-term zinc status, but are less reliable than serum or plasma zinc tests (27).

Supplementing with zinc can improve zinc levels in people who are deficient.

Zinc transport and absorption, nutrient interactions

Zinc is primarily absorbed in the jejunum, the second portion of the small intestine.

Several factors can interfere with the absorption of zinc in the jejunum, including:

Phytates: Phytates are natural compounds found in some plant foods, such as grains, legumes, and nuts. They can bind to zinc and other minerals in the gut, forming insoluble complexes that are difficult for the body to absorb. A study in women found that consumption of a high-phytate diet reduced zinc absorption by 35% compared to a low-phytate diet (28).
Fiber: Dietary fiber can also bind to zinc and reduce its absorption. A study in healthy men found that consumption of a high-fiber diet reduced zinc absorption by 25% compared to a low-fiber diet (29).
Iron: High levels of iron can interfere with zinc absorption, as the two minerals compete for the same absorption pathways. A study in women found that consumption of a high-iron diet reduced zinc absorption by 50% compared to a low-iron diet (30).
Calcium: High levels of calcium can also interfere with zinc absorption, as they can form insoluble complexes in the gut. A study in women found that consumption of a high-calcium diet reduced zinc absorption by 50% compared to a low-calcium diet (31).

It’s worth noting that while these factors can reduce zinc absorption, they are also important components of a healthy diet and should not be avoided altogether. Rather, it’s important to ensure adequate zinc intake through a varied diet or supplementation, as needed.

Zinc supplementation, homeostasis, and bioavailability

There is an inverse relationship between dietary zinc intake and the percentage of intestinal zinc absorption, meaning that as dietary zinc intake increases, the percentage of the zinc absorbed from the gut decreases (32). This is because the body has regulatory mechanisms in place to maintain zinc homeostasis and prevent excess accumulation. However, even at high levels of dietary zinc intake, the absolute amount of zinc absorbed can still increase, up to a certain point

Several factors can impact zinc homeostasis and bioavailability, including:

Dietary factors: As mentioned earlier, phytates, fiber, iron, and calcium can all interfere with zinc absorption in the gut. In addition, high levels of certain minerals, such as copper, can also interfere with zinc absorption.
Age: Zinc absorption tends to decrease with age, particularly in older adults over the age of 60. This may be due to changes in gut function or metabolism.
Disease or medical conditions: Certain medical conditions, such as gastrointestinal disorders, liver disease, or sickle cell anemia, can interfere with zinc absorption or increase zinc excretion.
Medications: Some medications, such as diuretics, antacids, or antibiotics, can interfere with zinc absorption or increase zinc excretion.

The amount and duration of supplementation needed to correct a deficiency will depend on the individual’s level of deficiency and the severity of symptoms, if any. In general, zinc supplementation should be supervised by a healthcare provider, who can recommend the appropriate dose and monitor for any adverse effects.

Zinc and DNA

Zinc plays a critical role in DNA maintenance and repair, through its involvement in various pathways and processes. Here are some examples of how zinc helps with DNA maintenance and repair, along with relevant studies and references:

DNA replication: Zinc is required for the activity of many enzymes involved in DNA replication, including DNA polymerases and helicases. These enzymes help to unwind the DNA double helix, separate the two strands, and synthesize new strands. A study in yeast cells found that zinc deficiency impaired DNA replication and increased DNA damage (33).
DNA repair: Zinc is also important for the activity of enzymes involved in DNA repair, including base excision repair, mismatch repair, and nucleotide excision repair. These enzymes help to remove damaged or mismatched nucleotides from the DNA strand and replace them with the correct ones. A study in human cells found that zinc deficiency impaired DNA repair and increased susceptibility to DNA damage (34).
Telomere maintenance: Zinc is required for the activity of telomerase, an enzyme that adds telomere repeats to the ends of chromosomes. Telomeres are important for protecting the ends of chromosomes from degradation and fusion, and their maintenance is critical for genomic stability. A study in human cells found that zinc deficiency reduced telomerase activity and shortened telomeres, leading to increased DNA damage (35).

Overall, zinc is essential for maintaining the integrity of the genome and preventing DNA damage. Adequate zinc intake is important for supporting these processes and minimizing the risk of mutations, chromosomal abnormalities, and other genetic disorders.

Zinc and aging

Since, looking after DNA is so important for slowing down aging, zinc deficiency is a major problem for those who try to remain young.

Zinc levels are important to be maintained at sufficient levels to prevent aging, as zinc is involved in numerous processes that affect cellular and tissue function. Here are some examples of how zinc levels impact aging, along with relevant studies and references:

Immune function: Zinc is essential for proper immune function, including the development and activation of immune cells, the production of antibodies, and the clearance of pathogens. As we age, our immune function tends to decline, a phenomenon known as immunosenescence. Studies have shown that zinc deficiency can exacerbate immunosenescence and increase susceptibility to infections (36).
Oxidative stress: Zinc is also important for antioxidant defense, as it helps to activate enzymes such as superoxide dismutase (SOD) that scavenge free radicals and protect against oxidative damage. Oxidative stress is a hallmark of aging and is thought to contribute to age-related diseases such as Alzheimer’s disease and cardiovascular disease. Studies have shown that zinc deficiency can increase oxidative stress and exacerbate age-related damage (37).
Tissue repair: Zinc is involved in tissue repair and regeneration, particularly in the skin and gut. As we age, tissue repair becomes less efficient, leading to slower healing and increased risk of chronic wounds and infections. Studies have shown that zinc supplementation can improve wound healing and reduce the risk of infection in older adults (38).

Maintaining adequate zinc levels is essential for slowing down aging through supporting immune function, antioxidant defense, and tissue repair, all of which can help prevent aging and age-related diseases.

In addition to zinc being instrumental in DNA repair and preventing DNA breaks, it is one of the most important nutrients for those who want to look after their health.

Zinc and immune function

Zinc deficiency can impair immune function in several ways, affecting both innate and adaptive immunity. Here are some examples of how zinc deficiency can impact immune function, along with relevant studies and references:

Reduced phagocytosis: Zinc is important for the activity of phagocytic cells such as neutrophils and macrophages, which help to engulf and destroy pathogens. Zinc deficiency can impair phagocytosis and reduce the ability of these cells to clear infections (39).
Impaired cytokine production: Zinc is also important for the production of cytokines, which are signaling molecules that regulate immune function. Zinc deficiency can impair cytokine production, particularly of Th1-type cytokines such as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), which are important for the activation of T cells and the clearance of intracellular pathogens (40).
Reduced antibody production: Zinc is necessary for the development and function of B cells, which produce antibodies that target specific pathogens. Zinc deficiency can impair antibody production and reduce the ability of the immune system to mount an effective response to infections (41).
Increased susceptibility to infections: Overall, zinc deficiency can increase susceptibility to a wide range of infections, including bacterial, viral, and fungal infections. A systematic review and meta-analysis of clinical trials found that zinc supplementation reduced the incidence, duration, and severity of respiratory tract infections in children and adults (42).

These and other studies provide evidence that adequate zinc intake is important for maintaining proper immune function and reducing the risk of infections.

Zinc deficiency and COVID-19

There is some evidence to suggest that zinc deficiency may be associated with increased COVID-19 severity and mortality, possibly due to impaired immune function. However, more research is needed to fully understand the relationship between zinc and COVID-19 outcomes.

Zinc is important for immune function, and several studies have shown that zinc deficiency can impair immune responses to viral infections (43,44). Some researchers have hypothesized that zinc deficiency may be a risk factor for severe COVID-19 outcomes, as the virus can suppress the immune system and trigger inflammation (45). In addition, zinc has been shown to have antiviral properties against other coronaviruses and respiratory viruses (46,47), although its effects on SARS-CoV-2, the virus that causes COVID-19, are less clear.

Several observational studies have reported an association between low zinc status and increased COVID-19 severity or mortality (48,49), although it is difficult to establish causality in these types of studies. Clinical trials are needed to determine whether zinc supplementation can improve COVID-19 outcomes, particularly in individuals with low zinc status.

Zinc deficiency and widespread common conditions

Zinc deficiency has been shown to increase the risk of respiratory infections such as pneumonia, flu, and the common cold, and may also worsen the severity and duration of these infections. Here are some examples of studies and references that investigate the relationship between zinc deficiency and respiratory infections:

Pneumonia: Zinc deficiency has been associated with an increased risk of pneumonia, particularly in children and older adults. A systematic review and meta-analysis of clinical trials found that zinc supplementation reduced the incidence of pneumonia in children under 5 years old (50). A study in older adults found that those with lower serum zinc levels were more likely to develop pneumonia and had higher mortality rates (51).
Influenza: Zinc has been shown to have antiviral properties against influenza viruses, and zinc deficiency may increase susceptibility to influenza infection. A study in mice found that dietary zinc deficiency increased mortality and viral replication in response to influenza infection (52). A clinical trial in healthy adults found that zinc supplementation reduced the duration and severity of influenza-like illness (53).
Common cold: Zinc supplementation has been shown to reduce the incidence, duration, and severity of the common cold in several clinical trials (54). Zinc may help to inhibit the replication of rhinoviruses, the most common cause of the common cold (55).

These and other studies suggest that zinc deficiency may increase the risk and severity of respiratory infections, while zinc supplementation may help to prevent and treat these infections.

Zinc deficiency and sepsis

Sepsis is a potentially life-threatening condition that occurs when the body’s immune response to infection causes widespread inflammation and tissue damage. Zinc deficiency has been linked to an increased risk of sepsis and may also worsen sepsis outcomes.

Risk of sepsis: Several observational studies have reported an association between low zinc status and an increased risk of sepsis, particularly in critically ill patients. A study in hospitalized patients found that those with lower serum zinc levels had a higher risk of developing sepsis (56). Another study in critically ill patients found that those with low plasma zinc levels had a higher risk of developing infections and longer hospital stays (57).
Zinc supplementation and sepsis outcomes: Some clinical trials have investigated the effects of zinc supplementation on sepsis outcomes, with mixed results. A study in septic patients found that high-dose intravenous zinc supplementation improved clinical outcomes and reduced mortality rates (58). However, another study in septic shock patients found no significant difference in mortality or other outcomes between a group receiving zinc supplementation and a placebo group (59).

These and other studies suggest that adequate zinc status may be important for reducing the risk of sepsis and improving outcomes in septic patients, although more research is needed to fully understand the mechanisms and optimal dosages of zinc supplementation in this context.

Zinc deficiency and HIV

Zinc deficiency has been associated with an increased risk of HIV infection and progression to AIDS, as well as with various symptoms and complications of HIV/AIDS.

Risk of HIV infection: Several observational studies have reported an association between low zinc status and an increased risk of HIV infection. A study in Tanzanian women found that those with low plasma zinc levels were more likely to acquire HIV infection (60). Another study in Rwandan men and women found that those with low serum zinc levels had a higher risk of HIV infection (61).
Zinc supplementation and HIV/AIDS outcomes: Some clinical trials have investigated the effects of zinc supplementation on various outcomes in HIV/AIDS patients, with mixed results. A systematic review and meta-analysis of clinical trials found that zinc supplementation improved CD4 cell counts and reduced the risk of opportunistic infections in HIV-infected individuals (62). However, another review found little evidence of benefit from zinc supplementation in HIV/AIDS patients, and suggested that routine supplementation may not be justified (63).
Symptoms and complications of HIV/AIDS: Zinc deficiency may contribute to various symptoms and complications of HIV/AIDS, including diarrhea, skin problems, impaired wound healing, and impaired immune function. A study in HIV-infected patients found that those with low serum zinc levels had a higher risk of developing diarrhea (64). Another study in HIV-infected children found that those with low serum zinc levels had a higher risk of developing skin rashes and impaired wound healing (65).

Zinc deficiency may be common in HIV-infected individuals, and may contribute to various symptoms and complications of the disease. However, more research is needed to fully understand the mechanisms underlying these effects and the optimal dosages and formulations of zinc for HIV/AIDS patients.

Zinc deficiency and acne

There is some evidence to suggest that zinc deficiency may be linked to acne breakouts, and that zinc supplementation may be a useful adjunctive therapy for acne prevention and treatment.

Mechanisms of action: Zinc may exert several anti-acne effects, including reducing inflammation, inhibiting the growth of acne-causing bacteria, regulating sebum production, and promoting wound healing (66). These effects may be mediated by zinc’s role as a cofactor for various enzymes and transcription factors involved in these processes.
Evidence of deficiency: Some studies have reported lower serum or plasma zinc levels in patients with acne compared to healthy controls (67,68). However, other studies have found no significant differences in zinc levels between acne patients and controls (69,70). Therefore, it is unclear whether zinc deficiency is a causative factor in acne or simply a secondary consequence.
Zinc supplementation and acne outcomes: Some clinical trials have investigated the effects of zinc supplementation on acne outcomes, with mixed results. A systematic review and meta-analysis of randomized controlled trials found that oral zinc supplementation was associated with a significant reduction in inflammatory acne lesions, but had no significant effect on non-inflammatory lesions or overall acne severity (71). Another randomized controlled trial found that topical zinc sulfate improved acne severity scores compared to a placebo cream (72).

Zinc may play a role in acne pathogenesis and that supplementation may be a useful adjunctive therapy for some acne patients.

Zinc deficiency and child development

Zinc deficiency can lead to several developmental problems in children, and zinc supplementation has been shown to alleviate some of these problems. Here are some examples of the links between zinc deficiency and child development:

Growth retardation: Zinc deficiency can impair linear growth and weight gain in children, leading to stunted growth and malnutrition (73). This effect is thought to be due to zinc’s role in regulating the expression of growth hormone and insulin-like growth factor 1 (IGF-1).
Cognitive development: Zinc deficiency has been associated with impaired cognitive development and learning abilities in children (74). This effect may be mediated by zinc’s role in neuronal function and plasticity.
Immune function: Zinc deficiency can impair immune function in children, leading to increased susceptibility to infections and other diseases (75). This effect may be due to zinc’s role in the development and function of immune cells.
Diarrhea: Zinc supplementation has been shown to reduce the duration and severity of diarrhea in children, particularly in developing countries (76). This effect is thought to be due to zinc’s role in intestinal function and immunity.

Zinc deficiency can have a range of negative effects on child development, and zinc supplementation may be a useful intervention to improve growth, cognitive function, immune function, and other outcomes in children with zinc deficiency.

It is better to test children early for zinc deficiency as these problems accumulate.

Zinc deficiency and brain function, cognitive impairment

Zinc deficiency has been linked to impaired brain function and neurogenesis, and there is some evidence to suggest that zinc deficiency may contribute to the development of cognitive impairment diseases such as Alzheimer’s and dementia.

Neurotransmitter function: Zinc plays a critical role in the regulation of neurotransmitter function, particularly glutamate, which is involved in learning and memory (77). Zinc deficiency can impair glutamatergic neurotransmission and synaptic plasticity, which may contribute to cognitive deficits.
Neurogenesis: Zinc is involved in the regulation of adult neurogenesis, the process by which new neurons are generated in the brain (78). Zinc deficiency has been shown to impair neurogenesis in animal models, which may contribute to cognitive impairment.
Oxidative stress: Zinc is a key antioxidant in the brain, protecting against oxidative damage and inflammation (79). Zinc deficiency can increase oxidative stress and inflammation, which have been implicated in the pathogenesis of Alzheimer’s and other cognitive impairment diseases.
Beta-amyloid accumulation: Zinc has been shown to regulate the accumulation and aggregation of beta-amyloid, a key pathogenic factor in Alzheimer’s disease (80). Zinc deficiency may contribute to the accumulation of beta-amyloid in the brain, leading to cognitive impairment.

Zinc deficiency may be a risk factor for cognitive impairment diseases such as Alzheimer’s and dementia and that zinc supplementation may be a potential therapeutic intervention for these conditions.

Zinc deficiency and mental disorders

Zinc deficiency has been linked to mood swings and mental health problems such as depression, anxiety, and psychosis:

Neurotransmitter function: Zinc is involved in the regulation of several neurotransmitters, including dopamine, serotonin, and GABA, which are critical for mood regulation and mental health (81). Zinc deficiency can impair the function of these neurotransmitters, leading to mood swings and other mental health problems.
Oxidative stress: Zinc is a key antioxidant in the brain, protecting against oxidative damage and inflammation (82,83). Zinc deficiency can increase oxidative stress and inflammation, which have been implicated in the pathogenesis of depression and other mental health disorders.
Psychosis and schizophrenia: Some studies have found that zinc deficiency is more common in patients with psychosis and schizophrenia compared to healthy controls (84,85). Zinc supplementation has been shown to improve symptoms in some patients with schizophrenia, although the evidence is limited and conflicting (86).

Zinc deficiency may be a risk factor for mood swings, depression, anxiety, and other mental health problems, as well as for more severe conditions such as psychosis and schizophrenia.

Zinc deficiency and metabolic function

Zinc deficiency has been linked to a range of metabolic dysfunctions, including impaired glucose metabolism, abnormal lipoprotein metabolism, and mitochondrial dysfunction. Here are some examples of the links between zinc deficiency and metabolic function:

Glucose metabolism: Zinc is involved in the regulation of insulin secretion and glucose uptake in cells, and zinc deficiency can impair glucose metabolism (87). Several studies have found that zinc supplementation can improve glucose metabolism in patients with diabetes mellitus and in animal models (88,89).
Lipoprotein metabolism: Zinc is also involved in the regulation of lipoprotein metabolism, and zinc deficiency has been associated with abnormal lipoprotein profiles, including increased LDL cholesterol and decreased HDL cholesterol (90). Zinc supplementation has been shown to improve lipoprotein profiles in some studies, although the evidence is limited and conflicting (91).
Mitochondrial function: Zinc is important for mitochondrial function and energy production, and zinc deficiency can impair mitochondrial function and lead to oxidative stress (92). Several studies have found that zinc supplementation can improve mitochondrial function and reduce oxidative stress in animal models and in vitro studies (93,94).
Cell function: Zinc is involved in the regulation of several cellular processes, including DNA synthesis and repair, gene expression, and apoptosis (95). Zinc deficiency can impair these processes and lead to cell dysfunction and damage.

Zinc deficiency can have wide-ranging effects on metabolic function, including glucose and lipoprotein metabolism, mitochondrial function, and cell function. Zinc is essential for so many processes in our organism that its scarcity is noticeable and reflects on our health.

Zinc toxicity

Zinc supplementation is generally considered safe when taken within recommended doses, but high doses of zinc can cause toxicity and may interact with certain medications. It is important to consume supplements in moderation and zinc is no exception.

Recommended doses: The recommended daily intake of zinc varies depending on age, sex, and other factors, but generally ranges from 8-11 mg/day for adults. Doses up to 40 mg/day are generally considered safe for most people, but doses above 100 mg/day can cause toxicity (96).
Toxicity: Acute zinc toxicity can cause nausea, vomiting, abdominal pain, and diarrhea, while chronic zinc toxicity can cause copper deficiency, anemia, and neurological symptoms (97). Zinc toxicity is rare in healthy individuals, but can occur in people who consume large amounts of zinc supplements or who have genetic disorders that impair zinc metabolism (98).
Medication interactions: Zinc can interact with certain medications, including antibiotics, diuretics, and medications used to treat rheumatoid arthritis and osteoporosis (99). Zinc can reduce the absorption and effectiveness of these medications, so it is important to talk to a healthcare provider before taking zinc supplements if you are on any of these medications.
Other safety considerations: Zinc can also interfere with the absorption of other nutrients, including copper and iron, so it is important to maintain a balanced diet and to take zinc supplements as directed by a healthcare provider (100). Zinc supplements should also be avoided during pregnancy and breastfeeding, as high doses of zinc can be harmful to the developing fetus or infant (101).

While zinc supplementation is generally safe when taken within recommended doses, high doses of zinc can cause toxicity and may interact with certain medications.

Zinc supplementation forms

Zinc supplements are typically sold as varying forms of water-soluble salts such as zinc gluconate, zinc sulfate, zinc acetate, zinc citrate, zinc oxide, and zinc picolinate. They are slightly different but comparable in their efficacy and could be considered to be similar. Each of these supplemental forms contains different percentages of elemental zinc: zinc gluconate (14 percent), zinc sulfate (23 percent), zinc acetate (30 percent), zinc citrate (31 percent), zinc oxide (80 percent), and zinc picolinate (21 percent).

Each of these forms of zinc has different properties that affect their absorption and bioavailability.

Zinc gluconate: This form of zinc is commonly found in lozenges and is easily absorbed by the body. It is often used to treat cold and flu symptoms.
Zinc sulfate: This form of zinc is a common dietary supplement and is often used to treat zinc deficiency. It has good bioavailability, but can cause stomach upset in some people.
Zinc acetate: This form of zinc is often used in lozenges to treat sore throat and cold symptoms. It is easily absorbed by the body and has good bioavailability.
Zinc citrate: This form of zinc is commonly used in dietary supplements and has good bioavailability. It is easily absorbed by the body and is often used to support immune function.
Zinc oxide: This form of zinc is commonly used in sunscreen and other topical products. It has low bioavailability when taken orally and is often combined with other forms of zinc to improve absorption.
Zinc picolinate: This form of zinc is often used in dietary supplements and has good bioavailability. It is easily absorbed by the body and is often used to support immune function and overall health.

Zinc supplements can be helpful for individuals with zinc deficiency or certain health conditions, a balanced diet is generally the best way to ensure adequate zinc intake. Zinc is naturally found in a variety of foods, including oysters, red meat, poultry, beans, nuts, and whole grains. By consuming a balanced diet rich in these foods, most individuals can meet their daily recommended intake of zinc without the need for supplementation.

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