Zinc rarely gets the attention of headline nutrients like vitamin D or omega-3, but it is quietly indispensable. It is a structural or functional partner to hundreds of enzymes and proteins, involved in everything from DNA repair to the sense of taste. Crucially, the body has no real storage depot for zinc, so a steady dietary supply is needed — and mild shortfalls are more common than most people assume, particularly among older adults and those eating little animal protein [1].
The immune mineral
Zinc’s best-established role is in the immune system. Essentially every type of immune cell depends on it to develop and function, and even a modest deficiency measurably weakens the body’s defences [1]. This matters most at the extremes of life: immune competence shifts as we age, and older adults are both more prone to zinc deficiency and more vulnerable to infection — a combination in which correcting a shortfall can help restore immune responses [3].
Colds and respiratory infections
This immune link is why zinc is a perennial cold remedy — and here the evidence is genuinely mixed but not empty. Pooling randomized trials in adults, a 2021 review found that zinc (as lozenges or nasal formulations) modestly reduced the risk of catching respiratory infections and, once ill, tended to shorten symptoms by around two days compared with placebo [2]. The caveats are real: the studies were of low-to-moderate quality, the best formulation and dose remain unclear, and zinc lozenges commonly cause nausea and a bad taste. It is a modest, early-intervention tool — not a megadose cure — and the benefit is clearest when started promptly.
Skin, healing and growth
Because zinc is required by the enzymes that build and remodel tissue, it is central to wound healing and skin integrity. The classic signs of deficiency — skin lesions, poor wound repair, impaired growth in children and a dulled sense of taste and smell — all trace back to these roles [4]. This is also why zinc is a standard ingredient in some topical creams and why healing can stall in people who are genuinely deficient.
Who runs low, and how much
Most people who eat meat and shellfish get enough, but several groups are more likely to fall short: older adults (reduced intake and absorption), vegetarians and vegans (plant compounds called phytates bind zinc and cut how much is absorbed), and people with digestive conditions that impair uptake [1][3]. For them, food first — legumes, nuts, seeds, whole grains and, for those who eat it, red meat and oysters — is the sensible starting point, with a modest supplement as backup.
A word of caution on dose: zinc follows a “just enough” logic. Too much causes nausea in the short term, and sustained high intakes interfere with copper absorption, which can create a second deficiency. Everyday supplemental doses are best kept modest, and short courses of lozenges reserved for the start of a cold.