Glutamine supplementation in cystic fibrosis: A randomized placebo-controlled trial.

RATIONALE: Pulmonary infection and malnutrition in cystic fibrosis are associated with decreased survival. Glutamine has a possible anti-microbial effect, with a specific impact against Pseudomonas aeruginosa. We aimed to test the hypothesis that oral glutamine supplementation (21 g/day) for 8 weeks in adults with cystic fibrosis would decrease pulmonary inflammation and improve clinical status. METHODS: The study design was a randomized double-blind placebo-controlled study design with an iso-nitrogenous placebo. The primary analysis was intention to treat, and the primary outcome was change in induced sputum neutrophils. RESULTS: Thirty-nine individuals were recruited and thirty-six completed the study. Glutamine supplementation had no impact on any of the outcome measures in the intention-to-treat analysis. In the per protocol analysis, glutamine supplementation was associated with an increase in induced sputum neutrophils (P = 0.046), total cells (P = 0.03), and in Pseudomonas isolation agar colony forming units (P = 0.04) compared to placebo. CONCLUSIONS: There was no effect of glutamine supplementation on markers of pulmonary inflammation in the intention-to-treat analysis.

Impact of adopting low sodium diet on biomarkers of inflammation and coagulation: a randomised controlled trial.

BACKGROUND: A low sodium diet is an established intervention in the treatment of impaired renal function and hypertension which may modulate cardiovascular risk independent of recognised antihypertensive effects. Epidemiological data suggest that dietary sodium intake may be associated with systemic inflammation: another potential pathophysiological mechanism by which sodium intake may modify vascular disease. METHODS: We tested the hypothesis that adopting a low sodium diet may decrease biomarkers of systemic inflammation or coagulation using data from a randomised double-blind placebo-controlled trial. Participants (n=171; aged 18-65 years) in a randomised double-blind placebo-controlled trial of a low sodium diet for 6 weeks provided paired serum samples for analysis to assess the impact of adopting a low sodium diet on biomarkers of systemic inflammation and coagulation. RESULTS: There was a significant difference in 24-hour sodium urinary excretion between the low sodium intake and the normal sodium intake groups of 43 mmol (p<0.001). In the primary analysis there was no effect of adopting a low sodium diet on serum D-dimers, but high-sensitivity C-reactive protein (hsCRP) was reduced by 1.13 mg/L (95% confidence interval [95% CI], 0.03 to 2.22). However, after elimination of outlying high values for baseline serum hsCRP (>10 mg/L), this effect was attenuated (-0.47 mg/L; 95% CI, -1.25 to 0.31). CONCLUSIONS: Using data from a randomised double-blind placebo-controlled trial in asthma with objective confirmation of adherence to the low sodium diet, we report that adopting a low sodium diet for 6 weeks has no effect on measures of systemic inflammation or coagulation.

Does a low sodium diet modify heart rate variability? A randomised placebo-controlled double-blind trial.

BACKGROUND: Increased heart rate variability (HRV) is associated with a low risk of mortality, as is consuming a low sodium diet. As the survival benefits of a low sodium diet may be mediated partly by an increase in HRV, we have tested the hypothesis that adopting a low sodium diet increases HRV. METHODS: We used a randomised double-blind placebo-controlled trial design. Participants were aged 18-65 years old, had a physician diagnosis of asthma. All adopted a low sodium diet and they were randomised to receive either 80 mmol/day of oral sodium supplements (normal sodium intake - NSI) or matched placebo (low sodium intake-LSI) for 6 weeks. The primary outcome was change in SDNN (standard deviation of the N-N intervals); secondary outcomes were changes in other time domain and frequency domain measures of HRV. RESULTS: In those allocated to the LSI, mean daily urinary sodium excretion decreased by 22 mmol; and in those allocated to the NSI mean daily urinary sodium excretion increased by 31 mmol. There were no differences between the two groups for either the primary or secondary outcome measures. The mean difference in change in SDNN between those who received the LSI compared to the NSI was -2.7 ms (95% Confidence Intervals CI; -18.0 to +12.6). CONCLUSIONS: Adopting a low sodium diet does not have an impact on SDNN over a 6 weeks period. Future studies should aim to achieve a larger change in dietary sodium intake for a longer duration than 6 weeks.

Does a low sodium diet improve asthma control? A randomized controlled trial.

RATIONALE: Observational studies and initial randomized trials have indicated that a low sodium diet may improve asthma control. OBJECTIVES: We tested the hypothesis that a low sodium diet would improve asthma control over a 6-week period. METHODS: Participants with a physician diagnosis of asthma and measurable bronchial reactivity to methacholine entered a randomized double-blind placebo-controlled trial. All adopted a low sodium diet and were randomized to receive either 80 mmol/day of oral sodium supplements (normal sodium intake) or matched placebo (low sodium intake) for 6 weeks. The primary outcome was change in bronchial reactivity to methacholine; secondary outcomes were change in lung function, morning and evening peak expiratory flow, asthma symptoms score, daily bronchodilator use, Juniper Standardized Asthma Quality of Life Questionnaire score, and atopy. MEASUREMENTS AND MAIN RESULTS: A total of 220 individuals entered the study, of whom 199 completed the protocol. In the low sodium-intake group, mean daily urinary sodium excretion decreased by 20 mmol (SD, 64 mmol) and in the normal-sodium-intake group increased by 28 mmol (SD, 74 mmol). There were no differences between the two groups in the primary or secondary outcome measures; the mean difference in bronchial reactivity between the low- and normal-intake groups was -0.03 doubling doses of methacholine (95% confidence interval, -0.60 to 0.53). CONCLUSIONS: The use of a low sodium diet as an adjunctive therapy to normal treatment has no additional therapeutic benefit in adults with asthma and bronchial reactivity to methacholine.