Transfer factors are all natural substances that work by "teaching" your own immune system to identify infectious agents that attack your body. Transfer factors are very small components naturally found in colostrum, a baby’s first milk from its mother. Through an extraction process, companies are able to collect powerful transfer factor molecules from the first milk of cows and prepare them for human consumption. Chickens are also used in the production of specific transfer factors.
All mammals produce transfer factors. A healthy cow already produces millions of different transfer factors, but when the cow does come into contact with a pathogen such as a virus, it produces a new transfer factor for that specific virus or pathogen. Transfer factors cross mammalian species lines. When a person absorbs transfer factors from a cow’s colostrum, the person develops resistance to the pathogen to which the cow was exposed. To keep your body healthy, your immune system must do three very important things each time your body comes in contact with a pathogen: First it must first recognize the pathogen as a threat to the body; second, it must then attack and kill off the threat; and third, it must remember that pathogen so that your body can rid itself quickly of it the next time it is attacked. For example, when a person has been infected with chickenpox in childhood, the body develops a memory of that illness which prevents the person from becoming re-infected later in life.

It is the identification process of the immune system that is so critical. If your body can identify a pathogen quickly, it can mount a response against it quickly. By transferring information from cell to cell, transfer factors serve as "teachers" of new cells, thereby ensuring a stronger immune system.

For individuals challenged by specific pathogens, whether known or unknown, supplementation with the appropriate transfer factor molecule may provide the ‘missing link’, thereby allowing the immune system to target and destroy the offending pathogen, whether bacterial or viral, and mitigate the symptoms of the disease.

Chronically ill people may need to take a multipurpose transfer factor preparation for several months before starting to feel better.

Some companies have a selection of products, some designed to boost the immune system, and others to help balance it in case of overactivity or autoimmunity. One such company is Immunofoods or IMMC.