Updated June 2026 · Ireland Health Shop · The Honey Pot, Clonmel
Zinc is arguably the most important single mineral for immune health. It is required for the development and activation of T-lymphocytes (the adaptive immune cells that target specific pathogens), natural killer (NK) cells, and neutrophils. It also regulates cytokine signalling — the chemical messaging system that coordinates immune responses. Zinc deficiency causes a well-documented state of immune dysfunction, characterised by increased susceptibility to infections, reduced vaccine responses, and impaired recovery from illness.
The clinical evidence for zinc supplementation in immunity is some of the strongest in nutritional medicine. Meta-analyses have found that zinc lozenges, when started within 24 hours of cold symptom onset, reduce the duration of the common cold by an average of 33%. This effect requires adequate zinc reaching the throat and nasal passages directly — explaining why lozenges outperform capsules for this specific purpose.
The skin contains approximately 6% of the body's total zinc, concentrated in the epidermis where cell turnover is highest. Zinc is essential for keratinocyte (skin cell) proliferation and differentiation. It has significant anti-inflammatory properties in the skin and inhibits the growth of Cutibacterium acnes (the bacterium involved in acne). Zinc's effectiveness for acne has been demonstrated in multiple clinical trials — topical zinc and oral zinc are both used therapeutically.
Zinc is required at every stage of the wound healing process — from the inflammatory phase through to collagen synthesis and remodelling. Hospitals have long used zinc supplementation for burns patients and post-surgical patients with non-healing wounds. Low zinc levels consistently correlate with impaired wound healing. If you have a wound, ulcer, or post-operative site that's healing slowly, zinc status is worth checking.
Zinc is essential for the function of gustin (carbonic anhydrase VI), a protein that maintains taste bud structure and function. Loss of taste (ageusia) and smell (anosmia) are classic features of zinc deficiency — and one of the reasons many people supplemented zinc during and after respiratory infections in recent years, where taste and smell loss became widely recognised symptoms.
Zinc is required for the synthesis and action of several hormones, including testosterone, thyroid hormones, and insulin. It's a necessary co-factor for the enzyme that converts testosterone to its active form (DHT), and for the aromatase enzyme that regulates oestrogen balance. Low zinc is associated with low testosterone, reduced fertility in both men and women, and thyroid dysfunction.
Zinc is highly concentrated in the hippocampus (the brain region central to memory formation) and modulates NMDA glutamate receptors, which are fundamental to learning and memory. Adequate zinc status is associated with better cognitive performance, and some evidence suggests zinc supplementation can improve attention and working memory in deficient individuals.
The richest dietary sources of zinc are animal foods — particularly shellfish. Oysters contain more zinc per serving than any other food (approximately 74mg per 100g — roughly 7 times the daily requirement). Red meat, liver, poultry, and dairy are also good sources.
For the Irish diet specifically:
Key zinc food sources available in Ireland:
As with other minerals, the form matters:
High-dose zinc supplementation (above 25–40mg daily for extended periods) can displace copper — the two minerals compete for absorption. If taking zinc long-term at higher doses, include a small amount of copper (2mg daily) to prevent copper deficiency. Many quality zinc supplements include this pairing automatically.
Unlike iron (which is better absorbed on an empty stomach), zinc causes nausea in many people when taken without food. Always take zinc supplements with or after a meal. Space it from calcium and iron supplements by at least 2 hours.