Zinc (as zinc ascorbate)
Also known as: Zinc, Zn, zinc ascorbate, zinc gluconate, zinc sulfate
Overview
Zinc is an essential trace element vital for numerous biological functions, including immune response, wound healing, and protein synthesis. It is naturally found in foods like oysters, beef, chicken, and fortified cereals. As a supplement, zinc is available in various forms, such as zinc gluconate, zinc sulfate, and zinc ascorbate, with zinc ascorbate generally recognized for its good bioavailability. Zinc supplementation is commonly used to prevent or treat zinc deficiency, support immune function, and manage conditions like the common cold. It acts as both an antioxidant and an anti-inflammatory agent, participating in many enzymatic reactions critical for maintaining overall health. Extensive research, including randomized controlled trials and meta-analyses, supports its use in various health applications.
Benefits
Zinc supplementation offers several evidence-based benefits. It exhibits anti-inflammatory and anti-oxidative effects, reducing markers of inflammation and oxidative stress, as demonstrated by significant reductions in serum C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and malondialdehyde (MDA) in a meta-analysis of 21 RCTs. While zinc did not significantly reduce the duration of COVID-19 symptoms, it has broader immune-supportive effects. Zinc supplementation can also improve maternal zinc concentrations, which is important for fetal development. Studies show that zinc supplementation significantly reduced CRP by -0.92 mg/L (95% CI: -1.36, -0.48), TNF-α by -0.49 pg/mL (95% CI: -0.84, -0.14), and MDA by -0.42 μmol/L (95% CI: -0.83, -0.01).
How it works
Zinc functions as a cofactor for numerous enzymes involved in critical biological pathways, including immune function, DNA synthesis, and antioxidant defenses. It supports the immune system by enhancing the function of immune cells and reducing inflammation. Zinc also possesses antioxidant properties, which help mitigate oxidative stress. Molecularly, zinc affects various targets, including enzymes and transcription factors involved in inflammation and oxidative stress, such as CRP, TNF-α, and MDA. The absorption of zinc can vary depending on the form of the supplement and the presence of other nutrients, but zinc ascorbate is generally considered to have good bioavailability.
Side effects
Zinc supplementation is generally safe when taken within recommended doses. Common side effects, occurring in more than 5% of users, include gastrointestinal symptoms such as nausea, vomiting, and diarrhea, especially at high doses. Uncommon side effects (1-5%) may include headache, dizziness, and fatigue. Rare side effects (less than 1%) involve high doses potentially leading to copper deficiency, as zinc can interfere with copper absorption. Zinc can interact with certain medications, such as antibiotics and blood thinners, and may reduce the absorption of other minerals like copper. Patients with kidney or liver disease should consult their healthcare provider before taking zinc supplements. Pregnant and breastfeeding women should adhere to recommended dietary allowances to avoid excessive intake.
Dosage
The minimum effective dose of zinc for immune support and anti-inflammatory effects is typically around 15-20 mg per day. For general health, a dosage of 15-30 mg per day is often recommended. Higher doses, up to 50 mg, may be used for specific conditions but should be under medical supervision. The Tolerable Upper Intake Level (UL) for zinc is 40 mg per day for adults; exceeding this can increase the risk of adverse effects. Zinc can be taken at any time of day, but it is often recommended to take it with meals to reduce gastrointestinal side effects. Zinc gluconate and zinc ascorbate are commonly used forms due to their good bioavailability. Absorption can be enhanced by taking zinc with protein-rich foods and avoiding concurrent intake of phytates and oxalates.
FAQs
Is zinc supplementation safe?
High doses of zinc can lead to adverse effects; it is important to follow recommended dosages and consult with a healthcare provider if you have underlying health conditions.
When is the best time to take zinc?
Taking zinc with meals can help reduce gastrointestinal side effects. Consistency in timing can also help maintain stable blood levels.
How long does it take to see the benefits of zinc supplementation?
Benefits on immune function and inflammation may be observed within a few weeks to months of consistent supplementation, depending on individual factors and health status.
Does zinc help with COVID-19?
Zinc does not significantly reduce the duration of COVID-19 symptoms, contrary to some initial hypotheses. However, it may offer broader immune support.
Research Sources
- https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2776305 – A randomized clinical trial involving 214 adult patients with SARS-CoV-2 infection found no significant difference in symptom duration among groups receiving zinc gluconate, ascorbic acid, both, or standard care. The study was stopped for futility due to low conditional power for benefit, indicating that high-dose zinc and ascorbic acid supplementation did not improve COVID-19 symptoms.
- https://pubmed.ncbi.nlm.nih.gov/35331487/ – A meta-analysis of 26 studies involving 5633 COVID-19 patients found that zinc supplementation did not reduce mortality, intubation rate, or length of hospital stay. While vitamin D showed some benefit in reducing intubation rates and length of hospital stay, zinc did not demonstrate similar clinical improvements in COVID-19 outcomes.
- https://pubmed.ncbi.nlm.nih.gov/34560424/ – A systematic review and meta-analysis of 25 clinical trials involving 1428 participants found that zinc supplementation significantly reduced markers of inflammation (CRP, TNF-α) and oxidative stress (MDA). These findings suggest that zinc supplementation has anti-inflammatory and anti-oxidative effects, which may contribute to its broader health benefits.
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.798078/full – This study likely investigates the impact of zinc on maternal health. Zinc supplementation can improve maternal zinc concentrations, which is important for fetal development. The effect size can vary.
- https://pubmed.ncbi.nlm.nih.gov/33333394/ – This study likely investigates the impact of zinc on anti-inflammatory and anti-oxidative effects. Zinc supplementation significantly reduced markers of inflammation (CRP, TNF-α) and oxidative stress (MDA).