Circadian fluctuations in saliva biochemical composition: A pilot study

Saliva serves as a valuable, non-invasive diagnostic tool, yet the influence of circadian rhythms on its biochemical composition remains unclear. This study evaluated circadian fluctuations in unstimulated whole saliva, focusing on pH, total protein, glucose, and organic and inorganic ions. Eight healthy, caries-free adults provided unstimulated saliva samples at six time points (7:00 AM, 11:00 AM, 3:00 PM, 7:00 PM, 11:00 PM, and 3:00 AM) across a 24-hour period, on three separate days. Participants followed a standardized Mediterranean diet for three days before and during sampling. Saliva was analyzed for pH, total protein (bicinchoninic acid assay), and various biochemical markers using a calibrated reflectometer. Statistical analyses were performed using repeated measures ANOVA (p p >0.05). However, lactate, nitrate, nitrite, ammonium, and glucose exhibited significant circadian fluctuations (p