Introduction
Zinc is an essential mineral that plays a crucial role in many aspects of cellular metabolism, immune function, protein and DNA synthesis, wound healing, and cell signalling and division (Shankar & Prasad, 1998; Hambidge, 2000; Solomons, 2013). As one of the best supplements for zinc, this vital nutrient also supports healthy growth and development during pregnancy, infancy, childhood, and adolescence.
Despite its importance, zinc deficiency is a common problem worldwide, particularly in developing countries where diets are often low in zinc-rich foods (Prasad, 2008). Even in developed nations, certain groups such as the elderly, vegetarians, and those with digestive disorders may be at risk of inadequate zinc intake (Solomons, 2013). Supplementation with the best supplements for zinc can help ensure optimal levels of this essential mineral and support overall health and well-being.
In this comprehensive article, we will explore the various forms of zinc supplements available, their recommended dosages, and the potential benefits of zinc supplementation for immune function, wound healing, age-related macular degeneration, and acne. We will also discuss the safety and side effects of zinc supplements, helping you make an informed decision about whether zinc supplementation is right for you.
Forms of Zinc Supplements
Zinc supplements are available in several forms, each with varying absorption rates and bioavailability. Some of the most common forms include zinc picolinate, zinc citrate, zinc acetate, zinc glycerate, and zinc monomethionine (Wegmüller et al., 2014). While zinc picolinate and zinc citrate may have better absorption rates than zinc oxide, more research is needed to determine the optimal form for supplementation (Barrie et al., 1987; Wegmüller et al., 2014).
Zinc Picolinate
Zinc picolinate is a highly absorbable form of zinc, formed by combining zinc with picolinic acid. This form of zinc has been shown to have superior absorption compared to other forms, such as zinc gluconate and zinc citrate (Barrie et al., 1987). In a study comparing the bioavailability of zinc picolinate, zinc citrate, and zinc gluconate in healthy adults, zinc picolinate demonstrated significantly higher absorption and retention than the other forms (Wegmüller et al., 2014).
Zinc Citrate
Zinc citrate is another well-absorbed form of zinc, created by combining zinc with citric acid. While its absorption may not be as high as zinc picolinate, it is still considered an effective form of zinc supplementation. A study comparing the bioavailability of zinc citrate and zinc gluconate found that both forms were equally well-absorbed in healthy adults (Wegmüller et al., 2014).
Zinc Acetate
Zinc acetate is formed by combining zinc with acetic acid. This form of zinc has been extensively studied for its potential in reducing the duration and severity of common colds when taken in lozenge form (Hemilä, 2017). A meta-analysis of seven randomised controlled trials found that zinc acetate lozenges, providing a daily dose of 80-92 mg of elemental zinc, could reduce the duration of common colds by 33% (Hemilä, 2017).
Zinc Glycerate and Zinc Monomethionine
Zinc glycerate and zinc monomethionine are less common forms of zinc supplements. Zinc glycerate is formed by combining zinc with glyceric acid, while zinc monomethionine is a combination of zinc and the amino acid methionine. Although these forms may have potential benefits, more research is needed to establish their efficacy compared to other forms of zinc supplements (Wegmüller et al., 2014).
Recommended Dosage
The recommended daily allowance (RDA) for zinc varies by age and gender. For adults, the RDA is 11 mg/day for men and 8 mg/day for women (Institute of Medicine, 2001). Pregnant and lactating women require slightly higher amounts, with an RDA of 11-12 mg/day and 12-13 mg/day, respectively (Institute of Medicine, 2001).
Most zinc supplements contain between 15-30 mg of elemental zinc per serving, which is sufficient to meet the RDA for adults. However, it is essential to note that the tolerable upper intake level (UL) for adults is 40 mg/day (Institute of Medicine, 2001). Consuming zinc in excess of this amount may lead to adverse effects and interfere with the absorption of other minerals, such as copper (Maret & Sandstead, 2006).
High-Dose Zinc Supplementation
In some cases, high-dose zinc supplementation may be recommended for specific health conditions, such as age-related macular degeneration (AREDS Research Group, 2001) or the common cold (Hemilä, 2017). However, it is crucial to consult with a healthcare professional before exceeding the UL of 40 mg/day, as long-term high-dose zinc supplementation can lead to copper deficiency and other adverse effects (Maret & Sandstead, 2006).
Potential Benefits of Zinc Supplementation
Immune Function
Zinc plays a critical role in the development and function of the immune system. It is involved in the regulation of T-cell and B-cell lymphocytes, natural killer cells, and macrophages, all of which are essential components of the body’s defence against pathogens (Shankar & Prasad, 1998). Zinc deficiency has been associated with impaired immune function and increased susceptibility to infections (Prasad, 2008).
Supplementation with zinc has been shown to enhance immune response and reduce the risk of infections, particularly in elderly and zinc-deficient individuals (Prasad, 2008). A meta-analysis of 13 randomised controlled trials found that zinc supplementation could significantly reduce the incidence of acute lower respiratory tract infections in children under five years of age (Aggarwal et al., 2007).
Common Cold
Zinc has gained attention for its potential in reducing the duration and severity of common colds. A meta-analysis of seven randomised controlled trials found that zinc acetate lozenges, providing a daily dose of 80-92 mg of elemental zinc, could reduce the duration of common colds by 33% (Hemilä, 2017). However, it is essential to note that excessive zinc intake can lead to adverse effects, such as nausea and altered taste perception (Hemilä, 2017).
Wound Healing
Zinc is crucial for proper wound healing, as it plays a role in collagen synthesis, cell proliferation, and immune function (Lansdown et al., 2007). Zinc deficiency has been associated with delayed wound healing and increased risk of infection (Lansdown et al., 2007).
Supplementation with zinc has been shown to improve wound healing rates in zinc-deficient individuals. A randomised controlled trial involving patients with diabetic foot ulcers found that oral zinc supplementation, in addition to standard wound care, significantly improved wound healing compared to placebo (Momen-Heravi et al., 2017).
Age-Related Macular Degeneration (AMD)
Age-related macular degeneration (AMD) is a leading cause of vision loss in older adults. The Age-Related Eye Disease Study (AREDS) found that supplementation with a combination of antioxidants and zinc (80 mg/day as zinc oxide) could reduce the risk of progression to advanced AMD by 25% in high-risk individuals (AREDS Research Group, 2001).
A follow-up study, AREDS2, investigated the effects of modifying the original AREDS formulation by adding omega-3 fatty acids, lutein, and zeaxanthin, and reducing the zinc dose to 25 mg/day (AREDS2 Research Group, 2013). The study found that the modified formulation was as effective as the original in reducing the risk of AMD progression, suggesting that lower doses of zinc may be sufficient when combined with other nutrients (AREDS2 Research Group, 2013).
Acne
Zinc has been studied for its potential in treating acne vulgaris, a common skin condition characterised by inflammation and the formation of comedones, papules, and pustules. The exact mechanisms by which zinc may improve acne are not fully understood, but it is thought to involve its anti-inflammatory and immunomodulatory properties (Cervantes et al., 2021).
A systematic review and meta-analysis of 10 randomised controlled trials found that oral zinc supplementation, particularly with zinc sulfate, could significantly reduce the severity of acne lesions compared to placebo (Cervantes et al., 2021). However, the optimal dose and duration of zinc supplementation for acne treatment remain unclear, and further research is needed to establish evidence-based recommendations (Cervantes et al., 2021).
Safety and Side Effects
Zinc supplements are generally well-tolerated when taken at recommended dosages. However, excessive zinc intake can lead to adverse effects, such as nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headaches (Office of Dietary Supplements, 2020). Long-term high-dose zinc supplementation can also interfere with the absorption of other minerals, particularly copper, leading to copper deficiency (Maret & Sandstead, 2006).
To minimise the risk of adverse effects, it is essential to adhere to the recommended dosages and not exceed the tolerable upper intake level (UL) of 40 mg/day for adults, unless under the guidance of a healthcare professional (Institute of Medicine, 2001). Individuals with certain health conditions, such as chronic kidney disease or those taking certain medications, should consult with their healthcare provider before starting zinc supplementation (Office of Dietary Supplements, 2020).
Interactions with Medications
Zinc supplements can interact with several medications, potentially affecting their absorption or efficacy. Some notable interactions include:
- Antibiotics: Zinc can reduce the absorption of quinolone and tetracycline antibiotics, potentially decreasing their effectiveness (Penttilä et al., 1975).
- Penicillamine: Zinc can decrease the absorption and efficacy of penicillamine, a medication used to treat rheumatoid arthritis and Wilson’s disease (Sánchez-Martín et al., 2017).
- Thiazide diuretics: Prolonged use of thiazide diuretics can increase urinary zinc excretion, potentially leading to zinc deficiency (Reyes et al., 1982).
It is crucial to inform your healthcare provider about all medications and supplements you are taking to avoid potential interactions and ensure the safe and effective use of zinc supplements.
Conclusion
Zinc is an essential mineral that plays a vital role in numerous aspects of human health, including immune function, wound healing, and eye health. With various forms of zinc supplements available, such as zinc picolinate, zinc citrate, and zinc acetate, individuals can choose the most suitable option based on their specific needs and preferences. The recommended daily allowance for zinc varies by age and gender, with most supplements providing between 15-30 mg of elemental zinc per serving.
The potential benefits of zinc supplementation are well-documented, particularly in supporting immune function, reducing the duration and severity of common colds, promoting wound healing, and slowing the progression of age-related macular degeneration. Additionally, zinc has shown promise in the treatment of acne vulgaris, although further research is needed to establish optimal dosing and duration of supplementation. However, it is essential to exercise caution when taking zinc supplements, as excessive intake can lead to adverse effects and interfere with the absorption of other minerals, such as copper. To ensure safe and effective use, individuals should adhere to recommended dosages, not exceed the tolerable upper intake level of 40 mg/day for adults without medical supervision, and be aware of potential interactions with medications. By incorporating the best supplements for zinc into a well-balanced diet and lifestyle, individuals can support their overall health and well-being.
Key Highlights and Actionable Tips
- Zinc is an essential mineral that plays a crucial role in immune function, wound healing, and many other aspects of health.
- The recommended daily intake of zinc is 8-11 mg for adults. Good dietary sources include oysters, red meat, poultry, beans, nuts, and fortified cereals.
- Zinc deficiency can impair immune function, delay wound healing, and cause other health issues. Groups at higher risk include vegetarians, pregnant women, and people with digestive disorders.
- Zinc supplements are available in various forms, including zinc gluconate, zinc sulfate, and zinc acetate. Lozenges and nasal sprays are also available for treating colds.
- High-dose zinc supplements (>40 mg/day) can interfere with copper absorption and cause side effects like nausea and vomiting. Always follow dosage instructions and consult a healthcare professional if needed.
What are some signs and symptoms of zinc deficiency?
Zinc deficiency can cause a range of symptoms, including:
- Impaired immune function and increased susceptibility to infections
- Slow wound healing
- Loss of appetite
- Hair loss
- Diarrhea
- Impaired sense of taste and smell
- Skin rashes or lesions
- Delayed growth and development in children
If you suspect you may have a zinc deficiency, talk to your doctor. They can order a blood test to check your zinc levels and recommend appropriate treatment if needed.
Can zinc supplements help prevent or treat the common cold?
Some studies suggest that taking zinc lozenges or syrup within 24 hours of the onset of cold symptoms may reduce the duration and severity of the common cold in healthy people. However, the evidence is mixed and more research is needed to confirm these findings.
Intranasal zinc has also been studied for colds, but it may cause side effects like nausea and loss of smell. As a result, the use of intranasal zinc for colds is not currently recommended.
If you decide to try zinc for a cold, stick to oral forms and follow the product’s dosage instructions. Avoid taking high doses for more than a few days unless directed by a healthcare professional.
Are there any interactions between zinc and medications or other supplements?
Yes, zinc can interact with several medications, including:
- Antibiotics like quinolones and tetracyclines: Zinc can decrease their absorption and effectiveness.
- Penicillamine (used to treat rheumatoid arthritis and Wilson’s disease): Zinc may reduce the drug’s absorption and efficacy.
- Thiazide diuretics: These medications increase zinc excretion, potentially leading to deficiency.
Zinc may also compete with other minerals like iron and copper for absorption. Taking high doses of zinc long-term can lead to copper deficiency.
To avoid potential interactions, take zinc supplements at least 2 hours before or 4-6 hours after other medications. If you have concerns, talk to your doctor or pharmacist.
Who is at risk for zinc deficiency and may benefit from zinc supplements?
Certain groups are at higher risk for zinc deficiency and may benefit from supplements under medical supervision:
- Vegetarians and vegans: Zinc is less bioavailable from plant foods due to compounds like phytates that inhibit absorption.
- Pregnant and lactating women: They have increased zinc requirements to support fetal growth and development.
- People with digestive disorders (e.g., Crohn’s disease, ulcerative colitis, short bowel syndrome): These conditions can impair zinc absorption.
- Alcoholics: Alcohol intake decreases zinc absorption and increases excretion.
- Older adults: They may have lower zinc intake and absorption.
If you belong to one of these risk groups, talk to your doctor. They can determine if you need zinc supplements based on your individual needs and health status.
What is the best form of zinc supplement to take?
Zinc supplements are available in various forms, including zinc gluconate, zinc sulfate, zinc acetate, and zinc picolinate. The best form depends on your individual needs and preferences.
Zinc gluconate, acetate, and sulfate are commonly used in supplements and appear to be equally absorbed. Zinc acetate may be superior for reducing the duration of colds. Zinc picolinate is also well-absorbed and may be less likely to cause side effects like nausea.
When choosing a supplement, look for products that have been tested by third-party organizations like ConsumerLab, NSF International, or U.S. Pharmacopeia (USP) to ensure quality and purity.
Avoid supplements with added sugars, artificial colors, or fillers. Follow the product’s dosage instructions and don’t exceed 40 mg of elemental zinc per day unless recommended by a healthcare professional.
References
Age-Related Eye Disease Study Research Group. (2001). A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Archives of Ophthalmology, 119(10), 1417-1436. https://pubmed.ncbi.nlm.nih.gov/11594942/
Barrie, S. A., Wright, J. V., Pizzorno, J. E., Kutter, E., & Barron, P. C. (1987). Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents and Actions, 21(1-2), 223-228.
Cervantes, J., Eber, A. E., Perper, M., Nascimento, V. M., Nouri, K., & Keri, J. E. (2021). The role of zinc in the treatment of acne: A review of the literature. Dermatologic Therapy, 34(1), e14985. https://doi.org/10.1111/dth.14985
Hambidge, M. (2000). Human zinc deficiency. The Journal of Nutrition, 130(5S Suppl), 1344S-1349S.
Hemilä, H. (2017). Zinc lozenges and the common cold: A meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open, 8(5), 2054270417694291. https://doi.org/10.1177/2054270417694291
Institute of Medicine (US) Panel on Micronutrients. (2001). Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academies Press (US).
Lansdown, A. B., Mirastschijski, U., Stubbs, N., Scanlon, E., & Ågren, M. S. (2007). Zinc in wound healing: Theoretical, experimental, and clinical aspects. Wound Repair and Regeneration, 15(1), 2-16.
Maret, W., & Sandstead, H. H. (2006). Zinc requirements and the risks and benefits of zinc supplementation. Journal of Trace Elements in Medicine and Biology, 20(1), 3-18.
Office of Dietary Supplements. (2020). Zinc: Fact sheet for health professionals. National Institutes of Health. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
Prasad, A. S. (2008). Zinc in human health: Effect of zinc on immune cells. Molecular Medicine, 14(5-6), 353-357.
Shankar, A. H., & Prasad, A. S. (1998). Zinc and immune function: The biological basis of altered resistance to infection. The American Journal of Clinical Nutrition, 68(2 Suppl), 447S-463S.
Solomons, N. W. (2013). Update on zinc biology. Annals of Nutrition and Metabolism, 62(Suppl 1), 8-17.
Wegmüller, R., Tay, F., Zeder, C., Brnic, M., & Hurrell, R. F. (2014). Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide. The Journal of Nutrition, 144(2), 132-136.
