Does social support affect our immune function?

The idea that one factor like social support can affect disease and death from virtually all causes is at odds with one of the most fundamental precepts of modem medicine: Koch's postulate. In the nineteenth century, the German physician Robert Koch won the Nobel Prize for being one of the first to identify a specific agent (the tubercle bacillus) as the cause of a specific illness (tuberculosis). According to Koch, and later to the French scientist Louis Pasteur, who developed the germ theory, an organism is proven to cause a disease if you find it in animals or people who have the disease and if you inject it into animals or humans and can cause the disease. Diseases were caused by a single microbe and thus treatment should be directed at eradicating this microorganism.

The problem with Koch's Postulate is that most people are not exposed to bacteria or viruses by injecting them (intravenous drug users being a notable exception). Bacteria, viruses, and other microorganisms must first penetrate through our immune, neuroendocrine and other defense systems. These defenses are enhanced and buffered by love and relationships. Not everyone exposed to bacteria and viruses becomes ill - otherwise, doctors and nurses who take care of patients would be sick all the time.

Even Pasteur changed his thinking later in life and believed that germs were only part of the picture and that other factors usually played an even more important role. According to legend, Pasteur said on his deathbed, "Le germe n 'est rien, c'est le terrain qui esttout" ("The microbe is nothing, the soil is everything").

In other words, exposure to bacteria, viruses, and other pathogens may be necessary but not sufficient to cause illness. For example, most people who test positive for being infected with the tubercle bacillus never develop tuberculosis. Most people who are infected with influenza viruses do not get the flu.

I cite a number of studies in chapter 2 of book Love and Survival that demonstrate that love and relationships are protective. They enhance our immune function and strengthen our resistance to disease. To use Pasteur's metaphor, loneliness and isolation help create a fertile soil for microbes to grow.