The effect of food deprivation on the circadian rhythms in flow rate and protein concentration in human parotid saliva

Abstract

The present experiments were designed to determine whether fasting during the morning would influence the circadian rhythms in the flow rate of unstimulated parotid saliva and in the protein concentrations in unstimulated and stimulated parotid saliva. With normal dietary intake, these rhythms are of high amplitude and show minimum values in the early morning and maximum values in mid-afternoon. Studies on nine individuals, with and without fasting, revealed that fasting had no effect on the circadian rhythm in the flow rate of unstimulated parotid saliva and reduced by only about one third the increase in protein concentration which occurs between 0700 and 1300 hr with normal food intake. Thus the major factor responsible for the circadian rhythm in parotid salivary protein concentration remains uncertain, as does the mechanism for the effect of normal food intake.