Well nourished persons have long been believed more resistant to infections than those who are undernourished or wasted. This belief, however, has been challenged repeatedly. Thus, even as long ago as the American Revolutionary period Underwood1 pointed out that infantile paralysis most often attacks the best nourished—"finest"—children. Rous2 in 1911 showed that undernourished fowl are relatively immune to sarcoma virus, while more recently Rivers3 has suggested a theory to explain "malnutritional immunity" based on the assumption that undernourished cells are lacking in biotin or other stored food materials necessary for the proliferation of viruses. This is a modernized restatement of the historic exhaustion theory of acquired immunity, discarded fifty years ago on the discovery of diphtheria antitoxin.
Recently Sprunt4 reported that prolonged fasting may cause a tenfold increase in the normal antiviral resistance of rabbits, provided the animals have free access to drinking water during the