Vitamin C was initially identified as a factor in reducing risk of scurvy and became popular for its antioxidant properties. It is an important co-substrate of a large class of enzymes and regulates gene expression by interacting with important transcription factors. Vitamin C is important during stressful conditions and critical for immunity. Vitamin C is essential to stimulate the immune system by increasing the strength and protection of the organism. Therefore, its immunostimulant role is well known.

Vitamin C has been shown to have significant immune function. Immune cells accumulate vitamin C against a concentration gradient, with a close relationship between vitamin C supply and immune cell activity, especially phagocytosis activity and T-cell function. Accordingly, one of the consequences of vitamin C deficiency is impaired immunity, while an enhanced supply increases antibody activity and infection resistance. And there is evidence that taking vitamin C can help upper respiratory discomfort go away faster.

A scientific journal review on vitamin C notes that it contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. Vitamin C supports immune epithelial barrier function and promotes oxidant scavenging activity. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, and generation of reactive oxygen species. It is also needed for apoptosis and clearance of spent neutrophils from sites of infection by macrophages, thereby decreasing necrosis/NETosis and potential tissue damage. In lymphocytes vitamin C has been shown to enhance differentiation and proliferation of B- and T-cells, likely due to its gene-regulating effects. Vitamin C deficiency results in impaired immunity and higher susceptibility to infections. In turn, infections significantly impact on vitamin C levels due to metabolic requirements.

One study investigated the role of vitamin C, at concentrations equivalent to those obtained from oral intakes, on key functions of neutrophils isolated from healthy individuals. Neutrophils are a type of immune cell that is one of the first cell types to travel to the site of an infection. The study measured the effects of enhanced vitamin C uptake on the essential functions of chemotaxis, oxidant production, programmed cell death and neutrophil extracellular trap (NET) formation. Extracellular vitamin C appeared to enhance neutrophil directional mobility. Stimulation of neutrophils in the presence of vitamin C significantly increased intracellular vitamin C concentrations and NET formation was significantly attenuated. The study found that neutrophils regulate their uptake of vitamin C from the plasma of healthy humans to maintain an optimal level within the cell for proper functioning. The study concluded that oral intakes of vitamin C may help reduce tissue damage and modulate healthy NET formation.

Zinc

The essentiality of zinc in humans was established in 1963. During the past five decades, tremendous advances in both clinical and basic sciences of zinc metabolism in humans have been observed. Cell-mediated immune function is a major clinical effect of zinc in humans. Over 300 enzymes and >1000 transcription factors require zinc for their activities. Zinc is an immune cell messenger, and intracellular free zinc in these cells participate in signaling events. Zinc has been successfully used to reduce upper respiratory symptoms. Zinc not only modulates cell-mediated immunity but is also an antioxidant. Zinc supplementation in the elderly results in reduced risk of infections, decreased oxidative stress and decreased generation of cytokines.

Zinc ions are involved in regulating intracellular signaling pathways in innate and adaptive immune cells. Zinc homeostasis is largely controlled via the expression and action of zinc "importers" (ZIP 1-14), zinc "exporters" (ZnT 1-10), and zinc-binding proteins. Antioxidant properties of zinc have long been documented. Zinc homeostasis-related effects include the activation of key signaling molecules, as well as epigenetic modifications. This emphasizes the role of zinc as a gatekeeper of immune function.

Diets deficient in zinc lead to impaired immunity and delayed recovery from and worse outcomes following infection. Sustained insufficient zinc intake leads to dysregulation of the innate immune response and increases susceptibility to infection whereas zinc supplementation in at-risk populations has been shown to restore host defense. Upon infection, zinc deficiency leads to increased pathology due to imbalance in key signaling networks that result in excessive inflammation and collateral tissue damage. In particular, zinc impacts macrophage function, a critical front-line cell in host defense, in addition to other immune cells. Deficits in zinc adversely impact macrophage function resulting in dysregulation of phagocytosis, intracellular destroying, and cytokine production. Zinc is also critical for several transporter proteins required for proper bioredistribution of zinc within mononuclear cells to achieve an optimal immune response.

Andrographis

Andrographis paniculata is a plant that has been effectively used in traditional Asian medicines for centuries. The aerial part of the plant, used medicinally, contains a large number of chemical constituents, mainly lactones, diterpenoids, diterpene glycosides, flavonoids, and flavonoid glycosides. Controlled clinical trials report its safe and effective use for reducing symptoms of upper respiratory tract infections. Andrographis also exhibits immunomodulatory effects by effectively enhancing cytotoxic T cells , phagocytosis, and antibody-dependent cell-mediated cytotoxicity (ADCC).

Andrographis is an annual plant, 1-3 ft high, that is one of the most commonly used plants in the traditional systems of Unani and Ayurvedic medicines. It is also used as a traditional herbal medicine in China, Hong Kong, the Philippines, Malaysia, Indonesia, and Thailand.

Doctor's Best Immune Support with Andrographis uses AP-Bio, a fast-acting Andrographis paniculata with 7 bioactives, clinically researched to manage all the symptoms of overall immune health at a low dose. Andrographis paniculata is widely used in India and China as traditional medicine for managing upper respiratory conditions that include cough, expectoration, nasal discharge, headache, fever, sore throat, earache, sleep disturbance, and malaise or fatigue. Most of the commonly used remedies target only 1 or 2 conditions whereas AP-Bio is known to support the management of multiple conditions providing faster relief. AP-Bio is standardized into 7 phytoconstituents -Andrographolide, Isoandrographolide, Neoandrographolide, 14-deoxy-11,12-didehydroandrographolide, Andrograpanin, Skullcapflavone-I, and 7-O-methylwogonin.