High Potassium Diet with Spices and Herbs As Salt Substitute for Lowering Blood Pressure in Older Adults: Study Protocol

Measurement of the change in systolic and diastolic blood pressure from baseline to Day 8 and Day 15 to evaluate the effect of the high-potassium, low-sodium diet intervention.

All participants were provided with written and verbal instructions on the correct procedure for 24-hour urine collection to measure Na and K levels. Nurses were also instructed to assist participants with this process. Participants were asked to ensure accurate 24-hour urine collection and report any missing or uncollected urine. The urine samples were then transported by researchers to an internationally certified ISO 9001 labor laboratory for analysis of Na and K levels using the ion-selective electrode (ISE) method, which specifically responds to anions and cations. Urinary K levels were categorized as low (< 25 mmol), normal (25-125 mmol), and high (> 125 mmol).

All participants were provided with written and verbal instructions on the correct procedure for 24-hour urine collection to measure Na and K levels. Nurses were also instructed to assist participants with this process. Participants were asked to ensure accurate 24-hour urine collection and report any missing or uncollected urine. The urine samples were then transported by researchers to an internationally certified ISO 9001 labor laboratory for analysis of Na and K levels using the ion-selective electrode (ISE) method, which specifically responds to anions and cations. Urinary Na levels were categorized as low (< 100 mmol), normal (100-260 mmol), and high (> 260 mmol).

Evaluation of changes in serum potassium levels as a response to dietary intake adjustments in the intervention group versus the control group. Serum potassium levels were determined through plasma blood testing using the ion-selective electrode (ISE) method. The samples were then transported by researchers to an internationally certified ISO 9001 laboratory. Plasma potassium levels were classified as follows: hypokalemia (< 3.5 mmol/L), normal (3.5-5 mmol/L), and hyperkalemia (> 5 mmol/L)

Measurement of plasma nitric oxide to assess vascular response to the dietary intervention.

Analysis of changes in plasma F2-isoprostane as an oxidative stress marker to monitor the potential antioxidative effects of the dietary intervention.

Measurement of plasma aldosterone levels to assess any physiological changes associated with potassium and sodium intake adjustments.

The concentrations of sodium and potassium in urine were measured and expressed in millimoles per liter (mmol/L). The Na/K ratio in urine was calculated by dividing the sodium concentration by the potassium concentration. This ratio was used to evaluate the electrolyte balance in the study participants.