Every year brings with it a new immune challenge that has everyone rushing around trying to shore up their immunity, either to the specific threat or to the usual and common bugs. This past year’s bout of H1N1 is only the latest prime example of this reactive behavior. Mix in the continuing economic challenges, and the situation is ripe for consumers to place more value on preventive immune support, including dietary changes and supplementation.
SPINS highlighted immunity in its trends report for 2010, noting with the flu scare still weighing on consumers’ minds, vitamins and supplements that boost the immune system should do well in the coming year. Specifically, the firm expects probiotics, medicinal mushrooms, Echinacea and astragalus to experience growth. Looking from another angle, SPINS indicated immunity is a big potential growing agent for probiotics and prebiotics used in foods and beverages for all age groups; additionally, children’s health will welcome immune products with innovative, kid-friendly delivery systems that encourage compliance.
A Layered Defense
The immune system is a multilayer masterpiece of barriers—mucosal surfaces, skin and other membranes—as well as chemical defenders that work together to ward off pathogens. These components work toward a balanced response, as some promote actions such as inflammation and apoptosis (cell death), while others counter those actions when the goal is achieved. Over-stimulating the system can lead to autoimmune problems, and a chronically suppressed system can lead to further infection; both extremes can lead to ongoing degeneration.
The important, dynamic components of this system are white blood cells called leukocytes, which include lymphocytes—B cells, T cells (T-helper and cytotoxic T cells) and natural killer (NK) cells—and monocytes, which become either macrophages (consume pathogens) or dendritic cells (activate T lymphocytes). Additionally, neutrophils hunt bacteria and fungi; eosinophils target larger parasites; and basophils are responsible for releasing histamine.
Un-activated B cells circulate through the lymph system until they are activated in the thymus or by a T cell to produce antibodies (i.e., immunoglobulins), which each specialize in a specific antigen. There are five classes of immunoglobulins: immunoglobulin G (IgG), IgA, IgM, IgD and IgE.
T cells form the basis of cell-mediated immunity by responding to body cells that have changed due to a virus or a cellular mutation. Among the various T cells, cytotoxic T cells cause cell death and attract macrophages for continued consumption of the foreign matter, and helper T cells, also known as CD4 or CD8 cells, stimulate the activity of cytotoxic T cells. The two subclasses of CD4 cells are Th1 and Th2, which each releases interleukins that trigger particular immune functions. Th1 response activates macrophages to kill pathogens, create inflammation, stimulate antibody production and secrete interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). And, Th2 responses feature high levels of antibody production, including secretion of certain antibodies and production of IL-4, IL-5, IL-10 and IL-30.
In addition to these immune cells, there are two fluid-like components. Complement, a mixture of proteins and proteases, can trigger production of cytokines that help kill foreign cells in membranes. Lymph, a plasma-like interstitial (between body cells) fluid, contains nutrients and white blood cells, and travels to and from lymph nodes, which are where lymphocytes meet antigens (foreign substances) caught up in the nodes.
The intricacies of immune function are carried over into research on various nutrients and nutraceutical ingredients and their effects on immune health. Immune function is a research hotbed, with new results coming out every month, matched only by the influx of new immune products. For retailers, deciding which products to carry and how to market them requires a review of what supplements are available, what the most recent science has to say about their effects, and to what lengths manufacturers can assure top quality and consistency in their products.