Fasting Enhances Immune Responsiveness

Deficiency of nutrients can occur from the consumption of an insufficient diet
over a prolonged period of time. Much of our population is indeed deficient in
essential plant-derived nutrients because of their overconsumption of fat,
protein, and. refined carbohydrate. Chronic exposure of experimental animals
to diets severely deficient in calories or essential nutrients results in
compromised cellular immunity. By contrast, short-term fasting followed by
controlled caloric restriction without malnutrition greatly increases longevity
and enhances immune responsiveness.

As early as 1911, researchers demonstrated that restricting the diets of
animals greatly improved their disease resistance and markedly increased
longevity as long as the restricted diet was not deficient in vitamins or
minerals. Subsequent research has shown that underfeeding reduces the
development of both spontaneous and induced tumors in rodents. Specifically,
underfeeding enhances cell-mediated immune function and prevents the
decrease in immune function associated with aging.

In non-obese humans the immunological response to caloric restriction and
weight loss has been studied under conditions of malnutrition, anorexia
nervosa, and voluntary fasting. The effect on immune function is marked.
Severe chronic malnutrition results in suppression of immune function and
increased infections. Anorexia nervosa patients, if consuming very few calories,
develop significant reductions in cellular immunity.However, no impairment
of immunity is seen until the patients become severely emaciated.18,19

In Dr. Anton Keys's classic study of the biology of human starvation, healthy
volunteers who fasted repeatedly had a decreased incidence of infection.
20 More
recently researchers evaluated the immune competence of patients before and
after a 14-day fast and noted enhancement in serum immunoglobulin levels,
skin testing response, and the bacteriocidal capacity of monocytes and natural
killer T cell activity. These researchers draw a parallel between their findings
and the enhanced immune responses seen in experimental animals following
fasting.

Fasting is very different from chronic malnutrition. Deficiency disease does
not occur as a result of the fast. Rather than suppressing immunity, which is
what happens in cases of long-term malnutrition and anorexia, fasting actually
does the opposite; it normalizes and enhances immune function.