Zinc is one of the trace elements that the body cannot produce itself – yet it is needed every day. As a cofactor of more than 300 enzymes, zinc controls key processes: immune defence, wound healing, cell division, skin and hair. Anyone considering a zinc supplement usually has three questions: Am I getting too little zinc? Which zinc form makes sense? And what is the right dosage? Current research from 2025 and 2026 provides concrete answers.
What zinc does in the body
Zinc can neither be produced nor stored in significant amounts. The total amount in the body is around 1.5 to 2.5 g – about 99% of it is found in tissues, and only around 1% in the blood. The highest concentrations are found in skeletal muscle (approx. 60%) and bone tissue (approx. 30%).
This trace element stabilises cell membranes and proteins, protects against oxidative stress and regulates communication between cells – essential for growth, differentiation and immune responses. Because zinc is lost daily through the intestines, kidneys and skin, it must be continuously supplied through the diet or a zinc supplement.
Zinc supplement and immune system: what current research shows
Two recent studies from RWTH Aachen under Prof. Lothar Rink, one of the internationally leading zinc researchers, show in very concrete terms how zinc influences the immune system.
Natural killer cells respond directly to zinc
A study published in 2025 in the Journal of Trace Elements in Medicine and Biology (Bennstein et al.) investigated the influence of zinc on natural killer cells (NK cells) – immune cells that recognise and destroy virus-infected and tumour cells. The result: The frequency of cytotoxic CD56dim NK cells correlated positively with serum zinc levels. After just 20 hours of zinc supplementation, a significantly higher activation of these cells was observed, together with an increased capacity for degranulation and increased production of interferon-gamma (IFN-γ). The cytotoxic protein perforin reacted particularly sensitively to zinc deficiency. The authors conclude that extracellular zinc specifically activates these killer cells.
Seniors: zinc deficiency measurably weakens the immune response
A second Aachen study, published in January 2026 in the International Journal of Molecular Sciences (Olah et al., DOI: 10.3390/ijms27021039), compared 78 older hospitalised patients (average age 82 years) with 112 young adults. The findings are clear: 46% of the seniors were zinc-deficient. They had significantly lower zinc levels and reduced IFN-γ production – a central cytokine of immune defence. The use of proton pump inhibitors (PPIs, acid blockers) also correlated with zinc deficiency. After around seven days of supplementation with zinc aspartate, serum zinc levels and IFN-γ production increased significantly.
Vegetarian and vegan diets: increased risk of zinc deficiency
Further data from the Aachen group show that vegetarians and vegans have an increased prevalence of zinc deficiency. Compared with mixed-diet eaters, the antiviral IFN-α response and the expression of the transcription factor IRF3 were significantly reduced. Both values could be normalised through oral zinc supplementation – an indication of the particular relevance of targeted supplementation in plant-based diets.
Zinc deficiency: symptoms and risk groups
Mild zinc deficiency often goes unnoticed because the symptoms are non-specific. Typical signs include patchy hair loss, brittle nails, impaired sense of taste and smell, skin changes, delayed wound healing and increased susceptibility to infections. In men, zinc deficiency can impair sperm production; in children, it can slow growth and development.
Groups with an increased risk of insufficient zinc intake include:
- Seniors aged 65 and over
- Vegetarians and vegans
- People with chronic inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
- Pregnant and breastfeeding women
- People who regularly take PPIs
- People with increased alcohol consumption
Zinc dosage: what is considered safe?
The German Nutrition Society (DGE) recommends 11 to 16 mg per day for men and 7 to 10 mg for women – depending on phytate intake (phytates from grains and legumes inhibit zinc absorption). Requirements are increased during pregnancy and breastfeeding.
The Tolerable Upper Intake Level (UL) set by EFSA is 25 mg zinc per day. At this amount, no negative effects are expected even with long-term intake. Higher dosages for the treatment of a confirmed deficiency are possible, but should be medically supervised. With long-term intake of higher doses, copper levels should be monitored, as zinc can influence copper absorption.
Which zinc form is best? Bisglycinate, picolinate or gluconate
Not every zinc compound is equally well absorbed. The decisive factor is bioavailability – in other words, how much of the supplied zinc the body can actually absorb.
Organic zinc compounds such as zinc bisglycinate, zinc picolinate, zinc gluconate and zinc orotate are considered more bioavailable than inorganic forms such as zinc oxide or zinc sulphate. Zinc bisglycinate (zinc bisglycinate 15 mg is also a frequently searched format) is a well-tolerated, organically bound form. Zinc picolinate is also well absorbed and is particularly gentle on the stomach. Products that combine several organic zinc forms can help support broader absorption.
Important: Zinc should not be taken at the same time as iron, copper or calcium salts – these can inhibit each other’s absorption. Coffee can also impair zinc absorption. With tetracyclines or quinolones (antibiotics), an interval of at least three hours should be maintained.
Zinc in food
Anyone wishing to cover their zinc needs through diet should focus on animal protein sources – they provide zinc in a form that the body can use better than plant-based sources.
| Food | Zinc content (approximate value) | Note |
|---|---|---|
| Oysters | ~70–80 mg per 6 pieces | Richest natural zinc source |
| Veal liver | ~8.4 mg per 100 g | Animal zinc, well bioavailable |
| Beef | ~6–8 mg per 150 g | Good everyday source |
| Wheat germ | ~7.2 mg per 60 g | Plant-based, but low in phytates |
| Pumpkin seeds | ~4–6 mg per 50 g | Good plant-based source |
| Edam cheese | ~4–5 mg per 50 g | Dairy products are well absorbed |
| Lentils (cooked) | ~1.7 mg per 100 g | Phytates inhibit absorption |
| Oat flakes | ~1.5 mg per 50 g | Soaking can improve absorption |
Values are approximate; actual contents vary depending on origin and preparation.
Plant-based sources such as legumes and whole grain products do contain zinc, but also phytates, which inhibit absorption. Sourdough whole grain breads have a more favourable ratio due to yeast activity.
Zinc and skin, hair, nails
Zinc is an underestimated factor for external appearance – not as a beauty product, but because it is involved in fundamental structural processes. This trace element stabilises the keratin structure via Zn²⁺-cysteine complexes: without sufficient zinc, keratin molecules lose strength and elasticity. This can appear as thin, brittle nails, Beau’s lines (horizontal grooves) or nail detachment – typical but often overlooked symptoms of zinc deficiency.
In hair loss, epidemiological data show that patients with alopecia areata or androgenetic alopecia often have reduced serum zinc levels. A causal relationship has not been proven for all forms, but in cases of confirmed zinc deficiency, supplementation is a sensible first step. The skin benefits from zinc in two ways: as antioxidant protection against oxidative cell stress and through the regulation of inflammatory processes – relevant for impure skin and delayed wound healing.
Zinc supplement: intake, interactions and tolerability
For a zinc supplement to work properly, the timing of intake and possible interactions matter. The most important points at a glance:
Timing of intake: Zinc is best taken on an empty stomach or at least one hour before eating, as meals – especially phytate-rich meals – inhibit absorption. Those with a sensitive stomach are better off taking zinc with a small meal.
Interactions with other minerals: Zinc, iron, copper and calcium compete for the same transport pathways in the intestine. Anyone supplementing several minerals should keep a time interval of at least two hours. With long-term zinc intake above 25 mg per day, accompanying copper intake is recommended, as zinc can inhibit copper absorption.
Interactions with medicines: Zinc reduces the absorption of tetracyclines and quinolones (classes of antibiotics) – there should be at least three hours between intake and the antibiotic. An interval is also recommended with penicillamine (a rheumatism medicine).
Coffee: Caffeine and tannins in coffee can impair zinc absorption. An interval of around one hour between coffee and a zinc supplement is recommended.
Contraindications: In cases of severely impaired kidney function or acute kidney failure, zinc should only be taken after consultation with a doctor.
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Conclusion: when is a zinc supplement worthwhile?
Zinc is a trace element with broad effects – from immune defence to skin and hair to cell division. Those who eat a varied, protein-rich diet often cover their needs through food. For seniors, people following a plant-based diet, people with bowel disease or those taking PPIs, targeted zinc supplementation may be useful. Current research shows that even short-term supplementation can have measurable effects on immune status. When selecting a product, it is worth looking at the zinc form used – organic compounds such as zinc bisglycinate or zinc picolinate are preferable to inorganic forms.
This article is for general information only and does not replace medical advice. Dietary supplements are not a substitute for a balanced and varied diet.
Sources
- Olah K et al. (2026). Zinc Supplementation Partially Reconstitutes Impaired Interferon-γ Production in the Elderly. International Journal of Molecular Sciences, 27(2), 1039. DOI: 10.3390/ijms27021039
- Bennstein SB et al. (2025). Extracellular zinc selectively activates CD56dim NK cells. Journal of Trace Elements in Medicine and Biology, 127788. ScienceDirect
- Baarz BR et al. (2022). Short-term zinc supplementation of zinc-deficient seniors counteracts CREMα-mediated IL-2 suppression. Immunity & Ageing. DOI: 10.1186/s12979-022-00295-8
- German Nutrition Society (DGE): Reference values for zinc. dge.de
- MSD Manual: Zinc deficiency. msdmanuals.com
