Zinc plays a pivotal role as a catalyst for metabolic activity, with over 200 enzymes being identified as zinc-dependent. Zinc is essential for growth, physical development, and for the metabolism of proteins, fats, and carbohydrates. Most aspects of reproductive biology require zinc, making this nutrient critical for female and male fertility.
Zinc deficiency is typically due to inadequate dietary consumption, chronic stress, vegetarianism, or excessive alcohol intake. Severe deficiency is associated with skin changes, diarrhoea, hair loss, mental disturbances, and recurrent infections because of impaired immune function.
Zinc’s Role in Immune Health
It is well-known in the scientific community that zinc is an essential mineral needed for healthy immune function. It is involved in virtually every aspect of the immune response and is considered a “gatekeeper of immune function” according to a review in the journal Nutrients.
Serum zinc concentration and zinc homeostasis are critical factors in both the innate and adaptive immune response, including antiviral activity against “common cold” viruses and respiratory tract infections, such as rhinoviruses, influenza, and coronaviruses.
Maintaining adequate zinc status supports immune cell differentiation, proliferation, and function, helping balance immune tolerance. Zinc deficiency can lead to overproduction of proinflammatory cytokines and other inflammatory mediators, lower regulatory T-lymphocyte (Treg) production, T-helper cell imbalance, and possibly even atrophy of the thymus gland. On the other hand, excessive levels may suppress T and B cell function, an overreaction of Treg cells, and direct activation of macrophage cells, the latter of which may be beneficial when infected cells are present.
Zinc-deficient populations are more susceptible to acquiring viral infections; deficiencies were shown to increase respiratory and diarrheal morbidity in children, demonstrating optimal nutritional status is a critical factor for maintaining immune health.
Zinc Lozenges and the Common Cold
According to a meta-analysis of randomised zinc lozenge trials published in JRSM Open, researchers investigated the effects of >75 mg/day of zinc acetate versus zinc gluconate lozenge supplementation on common cold duration. The results showed that both forms of zinc lozenges delivered within 24 hours of symptom onset in doses between 80-92 mg/day and 192-207 mg/day reduced the average duration of colds by 33%-35%, respectively.
Previous research published in Annals of Internal Medicine found that using zinc gluconate lozenges significantly reduced the complete resolution time of cold symptoms from an average of seven days to four days compared to a placebo.
The investigation was a randomised, double-blind, placebo-controlled trial that included 100 patients; 50 in the zinc group that was instructed to take one 13mg zinc gluconate lozenge every two hours, and 50 in the placebo group.
Researchers assessed oral temperature and subjective common cold symptom scores daily. There were significantly fewer days of coughing, headache, nasal congestion and drainage, hoarseness, and sore throat, but no significant difference between the placebo and zinc group for fever, sneezing, scratchy throat, and muscle aches.
It is important to recognise that participants in the zinc group did experience more adverse reactions than the placebo including taste alterations, which is a common symptom as zinc status greatly influences overall taste function.
Clinical Application
Unlike zinc capsules that must be digested and absorbed in the lower GI tract, the lozenge delivery system may be ideal for more rapid absorption and for targeting the problem areas most often affected during common cold and/or flu. Zinc delivered in lozenge form can allow the active ingredients to stay in the mucosal areas of the upper GI tract in order to support upper respiratory tract health, sore throats, and symptoms associated with the common cold and flu.
Many zinc lozenge products on the market are high in sugars and/or allergenic ingredients, which impact overall glycaemic load and may cause a heightened inflammatory response.
Moreover, most of the common zinc lozenge products typically only contain 5 milligrams or less of zinc, which may not be as effective. Encourage patients to choose zinc lozenges that have at least 13 milligrams of zinc gluconate per lozenge and that use “clean”, hypoallergenic ingredients with no sugar in order to increase their beneficial effects and to avoid impacting serum glucose levels.