The effect of chloride-containing potassium supplements on chloride titrator estimates of dietary sodium intake

Trial design: blood pressure control and weight gain prevention in prehypertensive and hypertensive smokers: the treatment and prevention study

BACKGROUND

Cigarette smokers with elevated blood pressure (BP) are at substantially higher risk for cardiovascular events compared to normotensive smokers. Although smoking cessation should be a primary treatment goal for these patients, increases in body weight accompanying smoking abstinence may further increase BP. Intervention strategies that facilitate smoking cessation and modify adverse changes in body weight and BP are needed.

METHODS

We describe an ongoing multi-site, two-phase, five-year randomized clinical trial. Participants are cigarette smokers with Prehypertension or Stage I Hypertension. In the first phase, participants receive a smoking cessation intervention combining behavioral counseling and nicotine replacement in an open-label fashion. In the second phase, participants who successfully quit smoking are randomly assigned to one of three lifestyle interventions: 1) weight gain prevention, 2) blood pressure control, or 3) usual lifestyle. Participants are followed for one year to assess changes in blood pressure, body weight, dietary intake, and physical activity.

CONCLUSIONS

Results from the proposed study will provide important insights into the efficacy of various approaches to lifestyle modification in smokers at increased risk for cardiovascular events.

Blood pressure response to potassium supplementation in normotensive adults and children

To investigate the effect on blood pressure of a modest increase in dietary potassium intake, 38 healthy, free-living families were enrolled in a study involving 4 weeks of potassium supplementation. This was preceded by collection of five baseline measurements of blood pressure and urinary electrolyte excretion and followed by a 4-week recovery period. Although there was a significant increase in urinary potassium excretion during supplementation in both adults and children (p less than 0.001), there were no significant changes in systolic, diastolic, or mean arterial blood pressure. Height and weight increased significantly in children (p less than 0.001), and weight increased in adults (p less than 0.01) over the course of the study. Multivariate analysis of variance of blood pressure controlling for these confounding variables failed to reveal any effect of the potassium supplementation on blood pressure. These results suggest that increasing intake of dietary potassium alone in a healthy, free-living normotensive population is unlikely to have a discernible effect on blood pressure.

The efficacy of quantitative and qualitative chloride titrators in the estimation of human salt intake

We evaluated the utility of chloride titrator sticks for facilitating the assessment of dietary salt intake, in a systematic series of clinical trials. These inexpensive devices were applied daily to 24-h or nocturnal urine specimens, thereby avoiding the inter- and intra-subject variability in salt excretion which confounds the use of occasional 24-h urine collections. Chloride and sodium concentrations in urine were highly correlated (r greater than 0.92) in either nocturnal, diurnal, or 24-h collections. The quantitative chloride titrator estimates and measured chloride concentrations were highly correlated as well (r greater than 0.99). The qualitative chloride titrator was graded on a simple scale, and was successfully employed by outpatients attempting to limit their salt intake. Commonly used antihypertensive medications did not interfere with the determinations. Additional chloride intake, such as supplemental potassium chloride, interfered with estimates of salt ingestion, but if the daily amount of potassium chloride supplement was constant, adjustments in interpretation could be made. Renal insufficiency introduced a systematic over-estimation of salt intake by the qualitative chloride tirator, but only at high salt intakes. Relative estimates of salt intake in subjects with renal failure were still possible. We conclude that chloride titrators can facilitate the management of patients who require a prescribed salt intake.