Dietary chloride as a possible determinant of the severity of exercise-induced asthma.
Dietary sodium chloride (NaCl) has been shown to alter the severity of exercise-induced asthma, but it is not known if the sodium and chloride ions have independent effects in this regard. The hypothesis tested in the present study was that both a low sodium, low chloride diet and a high sodium, low chloride diet would improve post-exercise pulmonary function in subjects with exercise-induced asthma (EIA) compared to a normal NaCl diet (NSD); but that neither of these diets would have an effect on post-exercise pulmonary function in control (non-EIA) subjects. Eight subjects who suffered from EIA and eight subjects who did not (control) took part in a double-blind crossover study. Pre- and post-exercise pulmonary function was assessed after 2 weeks on a NSD, a low NaCl diet (LSD, low sodium, low chloride) or a sodium bicarbonate diet (NaHCO3 diet, high sodium, low chloride). A 1 week washout period occurred between diets. Altering dietary sodium or chloride had no effect on pre-exercise (baseline) pulmonary function in either group or on post-exercise pulmonary function in control subjects. However, both the LSD and the NaHCO3 diet lessened the deterioration in post-exercise pulmonary function in EIA subjects. Comparing results from pre- to post-exercise, forced expiratory volume in 1 s (FEV1) at 15 min post-exercise differed significantly (P < 0.05) between diets [mean (SEM) 7 (4)% on the LSD, 14 (4)% on the NaHCO3 diet, and 19 (2)% on the NSD]. Similar patterns were observed for forced vital capacity (FVC), forced expiratory flow rate at 25%-75% FVC and peak expiratory flow rate. The NaHCO3 diet lessened the deterioration of post-exercise pulmonary function, but not to the extent of LSD. These data suggest that both sodium and chloride contribute to the worsening of EIA symptoms seen after consuming a normal or high NaCl diet.
Mickleborough
T D
TD
School of Sport Science, Physical Education and Recreation, University of Wales Institute, Cardiff, UK. Tmickleborough@uwic.ac.uk
Gotshall
R W
RW
Kluka
E M
EM
Miller
C W
CW
Cordain
L
L
D000138:Acidosis / Q000178:diet therapy / Q000503:physiopathology; D000328:Adult; D001250:Asthma, Exercise-Induced / Q000178:diet therapy* / Q000503:physiopathology*; D016084:Bronchoconstriction / Q000187:drug effects*; D004039:Diet, Sodium-Restricted; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D012720:Severity of Illness Index; D017673:Sodium Chloride, Dietary / Q000009:adverse effects*; D014797:Vital Capacity / Q000187:drug effects
D017673:Sodium Chloride, Dietary