Immune Function and Disease
Over the course of your lifetime, your immune system will face a multitude of challenges — from external pathogens as well as your body's own tissues and processes. An infection occurs when bacteria or other microbes get into your body and begin to multiply. The situation officially turns into a disease when the infection does damage to the cells and tissues and creates symptoms of illness. Illness can also occur when your immune system is pushed off course by problems known as immune deficiency disorders, or immunodeficiencies.
When it comes to human health, infectious agents can be broken into four categories: parasites, bacteria, viruses, and fungi.
Infectious parasites include the protozoa, or single-celled organisms, that cause malaria and a few types of foodborne illness. (Other protozoa, such as plankton, are harmless.)
Bacteria are tiny, single-celled creatures that can live on nonliving surfaces (such as countertops and stair railings) as well as on (or in) a living host.
Viruses are tiny microbes that contain one or two molecules of genetic material. They can't live on their own but instead must “hijack” living cells in order to survive and multiply.
Fungi are actually primitive plants (they include mushrooms, molds, and yeasts).
In healthy people, the immune system is ready and able to meet most of the challenges it will face. You'll encounter pathogens and, if they're strong or plentiful enough, you'll develop an infection, which your body will eventually defeat, and you'll go on to fight another day.
However, in people with compromised immunity, even the smallest threat — or things that aren't threatening at all, such as allergens or the body's own cells — can create serious, potentially fatal problems.
Many herbs and supplements are known as “immune-stimulating” agents, but not every immune system needs stimulating: If you've got allergies, asthma, or an autoimmune disorder, you've got an overactive immune system. Thus, you need something that's “immune-modulating” to help regulate your body's immune response (and turn it down, if necessary).
