Why Zinc Is a Foundational Mineral
Zinc is involved in over 300 enzyme reactions and is required for the structural function of over 1,000 transcription factors — proteins that regulate gene expression. It is essential for immune function, cell division and growth, wound healing, protein synthesis, testosterone production, and sensory function (taste and smell). The body has no specialised zinc storage system, making regular dietary intake critical.
Zinc deficiency is estimated to affect approximately 17% of the global population and is more common in the UK than most people realise — particularly in older adults, vegetarians (phytates in plant foods inhibit zinc absorption), heavy alcohol drinkers, and pregnant women.
Zinc and Immune Function
Zinc is one of the most evidence-backed nutrients for immune support. It's required for:
- Development and function of T-cells, B-cells, natural killer cells, and neutrophils
- Thymulin production (a thymic hormone that matures immune cells)
- Antioxidant enzyme function (superoxide dismutase)
- Inhibiting viral replication — including rhinovirus (common cold) replication
The most consistent clinical evidence is for zinc lozenges (acetate or gluconate form) reducing cold duration. A 2017 meta-analysis found zinc lozenges started within 24 hours of cold onset reduced cold duration by 33% on average. The lozenge format is important — the zinc needs contact with the oral and nasal mucosa to exert its antiviral effect directly.
Zinc and Testosterone
Zinc is essential for testosterone production — it's a cofactor for the enzymes involved in testosterone synthesis and it inhibits aromatase (the enzyme that converts testosterone to oestrogen). Zinc deficiency directly suppresses testosterone levels.
In zinc-deficient men, supplementation significantly increases testosterone. However, for men with adequate zinc status, supplementation produces only modest testosterone increases. The message: zinc optimises testosterone when deficient, but isn't a testosterone booster for replete individuals. Athletes who sweat heavily and vegetarians are at highest risk of zinc-related testosterone suppression.
Zinc for Skin and Wound Healing
Zinc is required for collagen synthesis, skin cell renewal, and wound healing. Topical and oral zinc has demonstrated effectiveness for acne — multiple RCTs show zinc (at doses of 30–45mg elemental zinc daily) significantly reduces inflammatory acne lesions, comparable to some antibiotics in mild-to-moderate cases. The anti-inflammatory and sebum-regulating properties of zinc are well-established.
Zinc for Fertility
Zinc is one of the most concentrated minerals in sperm and plays a critical role in sperm production, motility, and DNA integrity. Multiple studies link zinc deficiency to reduced sperm quality and male infertility. Supplementation in deficient men has been shown to improve sperm parameters and pregnancy rates.
How Much Zinc Do You Need?
The UK RNI is 9.5mg/day for men and 7mg/day for women. Rich dietary sources include: oysters (highest zinc food by far — 16–182mg/100g), beef (4.8mg/100g), pumpkin seeds (7.8mg/100g), lentils (2.5mg/100g), and cashews (5.6mg/100g).
For supplementation:
- General health maintenance: 10–25mg elemental zinc daily
- Acne or immune support: 30–45mg elemental zinc daily (short to medium term)
- Cold lozenges: 75mg+ daily of zinc acetate/gluconate, started within 24 hours of symptoms
Form Matters
- Zinc picolinate — highest bioavailability for systemic supplementation
- Zinc bisglycinate — well-absorbed, gentle on stomach
- Zinc gluconate — well-studied for cold lozenges specifically
- Zinc oxide — very poorly absorbed orally; primarily used topically
- Zinc sulphate — effective but more GI side effects
Important Cautions
Zinc can cause nausea if taken on an empty stomach — always take with food. Long-term high doses (50mg+/day) can deplete copper, as zinc and copper compete for absorption. If taking zinc long-term at higher doses, include copper supplementation (1–2mg copper per 15mg zinc) or use a balanced multi-mineral. Don't exceed 40mg elemental zinc daily for extended periods without medical guidance.
Bottom Line
Zinc is foundational for immune function, testosterone maintenance, skin health, and wound healing. The evidence for cold duration reduction with zinc lozenges is robust. Vegetarians, athletes, and older adults are at highest deficiency risk. Use zinc picolinate or bisglycinate at 15–25mg daily for general health; zinc gluconate/acetate lozenges (75mg+) at the onset of a cold. Always take with food and balance with copper if supplementing long-term at higher doses.