Quercetin is a naturally occurring antioxidant found in several plants. In vitro (i.e. laboratory-based) and animal studies have demonstrated Quercetin’s antiviral and antibacterial properties. Human clinical trials have shown that Quercetin can reduce the incidence of viral upper respiratory tract infection in the immediate post-exercise period following intensive exercise and in individuals suffering from high mental stress, conditions in which it is known that immune function is decreased and the incidence of viral infections is higher(1-4).

Zinc is a key ingredient that has been selected for its antiviral properties and its role in the regulation of immune function. A substantial amount of scientific literature has documented the beneficial role of zinc in fighting respiratory tract infections such as common cold and flu. The World Health Organisation (WHO) estimates that up to one third of the world’s population is deficient in zinc. An Australian study of 497 Tasmanian adults showed that zinc deficiency was present in 18% of men over the age of 50 and 30% of men over the age of 70(5). We have intentionally included high doses of elemental zinc in IMUNI Immune Defence to boost zinc levels, to enhance the antiviral effects of Quercetin and to improve viral defence.

Vitamin C has long been known for its antiviral and immune boosting properties. While a balanced diet can certainly assist in maintaining healthy intake, viral infections are associated with an increased metabolism of Vitamin C and reduced circulating levels. Regular supplementation of Vitamin C during and immediately prior to viral infection can therefore assist in maintaining effective immune function. Vitamin C has also been shown to improve the bioavailability of Quercetin by helping recycle Quercetin into its active form thereby optimising its antioxidant and antiviral effects.

Vitamin D plays an important role in the immune response as an immune modulator. A large study of over 10,000 patients enrolled in randomised clinical trials demonstrated that daily oral supplementation with vitamin D3 can prevent acute respiratory tract infection. While effects were more pronounced in patients deficient in vitamin D, even those people with normal blood levels still gained some benefit from vitamin D3 supplementation(6). In Australia, Vitamin D deficiency is common and affects nearly one-third of adults aged over 25 years of age(7).