Zinc deficiency — affecting 30–40% of older adults — impairs immune function, wound healing, and DNA repair, and is associated with higher rates of infection, cognitive decline, and all-cause mortality. Supplementation reverses these effects in deficient individuals.
Zinc is essential for immune function, wound healing, DNA synthesis, and protein production. Zinc deficiency affects approximately 30–40% of older adults due to reduced dietary intake, impaired absorption, and increased losses. Deficiency impairs T-cell function, reduces natural killer cell activity, and increases susceptibility to infections. Zinc supplementation in deficient older adults improves immune function and reduces infection rates.
Prasad (2009) in the Journal of the American College of Nutrition reviewed the evidence for zinc in aging, concluding that zinc deficiency is common in older adults and contributes to immunosenescence (age-related immune decline). Barnett et al. (2016) in the American Journal of Clinical Nutrition conducted a systematic review and found that zinc supplementation in older adults with zinc deficiency significantly improved immune function markers. Wessels et al. (2017) in Nutrients reviewed the mechanisms by which zinc deficiency impairs immune function, identifying reduced thymulin activity (required for T-cell maturation), impaired neutrophil function, and reduced natural killer cell cytotoxicity as key mechanisms.
"Zinc deficiency affects 30–40% of older adults and contributes to immunosenescence through multiple mechanisms including reduced thymulin activity and impaired T-cell function."
— Prasad, Journal of the American College of Nutrition 2009
MedlinePlus identifies zinc as an essential mineral for immune function and wound healing, noting that older adults are at risk of deficiency. The NIA recommends adequate zinc intake as part of a healthy diet for older adults. The recommended dietary allowance for zinc is 11 mg/day for men and 8 mg/day for women, with the tolerable upper intake level at 40 mg/day.
The best dietary sources of zinc are: oysters (74 mg per 85g — by far the richest source), beef (7 mg per 85g), crab (6.5 mg per 85g), pumpkin seeds (2.2 mg per 28g), and legumes (1–2 mg per 100g). Zinc from animal sources is significantly better absorbed than from plant sources due to phytates in plant foods. For older adults at risk of deficiency, zinc supplementation at 8–11 mg/day is appropriate. Zinc lozenges (zinc acetate or zinc gluconate, 13–25 mg/day) started within 24 hours of cold symptoms reduce cold duration by approximately 33%.
Vitaei verdict
Zinc deficiency is common in older adults and impairs immune function. Ensuring adequate intake through diet or supplementation is a practical immune support strategy, particularly for infection prevention.
How Does Chronic Stress Affect the Immune System and Accelerate Aging?
Chronic psychological stress dysregulates the immune system through sustained cortisol elevation, increasing susceptibility to infection, impairing vaccine responses, and accelerating biological aging by up to 10 years.
What Vitamins Should You Actually Take for Optimal Health?
Most healthy adults with a balanced diet do not need to take vitamin supplements. Evidence strongly suggests that routine supplementation offers no benefit and may even pose risks for the general population. Targeted supplementation is only indicated for specific deficiencies or physiological states.