CIRCADIAN-RHYTHM OF BREATH HYDROGEN IN YOUNG-WOMEN

Breath hydrogen levels, which reflect colonic fermentation of undigest ed starches, are usually low in the fasted state. Easting levels of br eath hydrogen are important for estimation of oro-cecal transit time a nd diagnosis of lactase deficiency. In young women, however, fasting l evels of breath hydrogen are high. To clarify the reason for this, we studied the circadian pattern of breath hydrogen and the effect of alp ha-D-galactosidase on fasting breath hydrogen in one study, and the ef fect of sleep deprivation on fasting breath hydrogen in another study, in 13 women students aged 21-23 years. In the first study, two breath samples were collected, one in the evening and the other the next mor ning. On another occasion, alpha-D-galactosidase was given before dinn er and breath samples were collected the next morning. In the second s tudy, the circadian rhythm of breath hydrogen was assessed for 3 days and the subjects were deprived of sleep on the second night. Breath sa mples were collected every 30 min, except during the second night when samples were collected at 1-h intervals. Easting breath hydrogen was 24 +/- 3.9 ppm (mean +/- SE), which did not differ from the value for the previous night. alpha-D-galactosidase significantly decreased fast ing breath hydrogen levels, to 17 +/- 2.4 ppm (P < 0.05). There was a clear circadian pattern of breath hydrogen, high in the morning and de creasing to the nadir by 16:00. After dinner, the level increased agai n and stayed high during the night. Sleep deprivation did not affect f asting levels of breath hydrogen. High fasting breath hydrogen levels in young women followed a circadian pattern and this may have been due . in part, to an high intake of dietary fiber on the previous day.