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Quick Answer
Zinc is an essential mineral that supports immune system function, wound healing, and protein production in the body. Studies consistently show that taking zinc close to the onset of cold symptoms may shorten the duration of the illness. People who suffer from zinc deficiency – such as vegans, older adults, or people with absorption issues – are at higher risk of deficiency, and may benefit from supplementation.
What It Is and How It Works
Zinc is a trace mineral that the body cannot produce on its own, so it must be obtained from food or supplements. It is part of hundreds of enzymes in the body and is involved in cell division, DNA and protein synthesis, and regulation of immune system response.
In the context of respiratory infections, zinc has mainly been studied for its ability to interfere with viral replication and support immune cells fighting infection. The body does not store large amounts of zinc, so regular intake is important for maintaining normal levels.
Research-Based Benefits
- Support for shortening cold duration: Studies consistently show that taking zinc within 24 hours of symptom onset may shorten the duration of a cold by a few days, compared to placebo.
- Support for normal immune function: Zinc deficiency impairs the function of various immune cells; supplementing the mineral in deficient individuals improves immune function.
- Support for skin health and wound healing: Zinc is involved in collagen production and cell division processes, and preliminary studies suggest a role in wound healing in people with deficiency.
- Support for eye health: Preliminary studies, mainly among older adults, suggest a link between zinc (usually combined with additional antioxidants) and support for eye health in older age – a finding that is not necessarily relevant to a young, healthy population.
- Male fertility: The evidence is mixed – some studies suggest a link between normal zinc levels and sperm quality, but results are inconsistent and further research is needed.
Dosage and Timing
The range commonly used in studies for immune support is several tens of milligrams per day, while shortening cold duration involved higher doses used only for a short term (a few days). The general Recommended Daily Allowance (RDA) is significantly lower than the therapeutic doses tested in cold-duration studies.
Regarding timing, some studies recommend taking zinc with food to reduce nausea, but note that certain foods (especially those high in calcium) may reduce absorption. Due to the large gap between “everyday” doses and “short-term therapeutic” doses, it is recommended to consult a doctor or clinical dietitian before taking a supplement, especially for an extended period.
Safety and Side Effects / Who Should Be Cautious
- Prolonged use at high doses may impair copper absorption and cause copper deficiency, affecting the blood and nervous systems.
- Common side effects include nausea, a metallic taste in the mouth (especially with lozenges), and stomach pain.
- Intranasal zinc (in sprays or drops) has previously been linked to reports of permanent loss of smell – these products have previously been removed from the FDA market, so intranasal forms should be avoided.
- People taking certain medications (such as quinolone or tetracycline antibiotics) should be cautious of interactions and should separate dosing times.
- Pregnant or breastfeeding women, children, and people with kidney disease should consult a doctor before taking a zinc supplement.
Who This Is For
- People following a strict vegan or vegetarian diet, where zinc absorption from plant sources is lower.
- Older adults, who are at increased risk of nutritional deficiency.
- People with inflammatory bowel disease or chronic absorption issues.
- Those who experience frequent colds and are interested in a potential option for shortening illness duration.
- High-intensity athletes, whom preliminary studies suggest may be at increased risk of deficiency due to zinc loss through sweat.
How to Choose a Quality Product
Look for a supplement in a chemical form with relatively good absorption, such as zinc citrate, zinc bisglycinate, or zinc picolinate – these forms are considered to have better bioavailability than the cheaper, less-absorbed zinc oxide form. It’s also worth checking that the product has undergone third-party testing (such as NSF or USP), which confirms that the actual content matches what’s stated on the label.
Where to Buy
You can find a variety of quality zinc supplements in different absorption forms through the following links:
FAQ
Should I take zinc every day as a preventive supplement?
Most people with a balanced diet don’t need regular daily supplementation; it’s generally better to reserve higher doses for periods of actual illness, and consult a doctor regarding ongoing use.
Can zinc prevent a cold from occurring in the first place?
The evidence mainly supports shortening the duration of illness when intake begins early, and less so complete prevention of infection.
What’s the difference between zinc citrate and zinc oxide?
Zinc citrate is considered more bioavailable and is likely to be better absorbed, while zinc oxide is cheaper but less effective in terms of absorption.
Can you get too much zinc from food alone?
This is very rare from food alone; most cases of excess result from high-dose supplements taken over time.
Is zinc suitable for children?
Consult a pediatrician before giving a zinc supplement to children, as the dosages and needs differ significantly from those of adults.
Disclaimer
The content in this article is intended for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult a doctor or healthcare professional before starting any dietary supplement, particularly during pregnancy, breastfeeding, while taking regular medications, or if you have an existing health condition.