Effect of Salt Restriction on Renin Activation

• Change in sodium levels in urine samples. [ Time Frame: 3 weeks ] [ Designated as safety issue: No ]
  Sodium was measured in 24-hour collected urine samples before the beginning of diet specific to their groups, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet.
• Change in plasma renin activity [ Time Frame: For 3 times in 8 weeks ] [ Designated as safety issue: No ]
  Plasma renin activity level was measured in the blood samples collected, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet.
• Change in aldosterone level in blood samples [ Time Frame: For 3 times in 8 weeks ] [ Designated as safety issue: No ]
  Aldosterone levels was measured in the blood samples collected , at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet.
• Change in potassium levels in urine samples. [ Time Frame: 3 weeks ] [ Designated as safety issue: No ]
  Potassium was measured in 24-hour collected urine samples before the beginning of diet specific to their groups, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet.
• Change in urea level in urine samples [ Time Frame: 3 weeks ] [ Designated as safety issue: No ]
  Urea was measured in 24-hour collected urine samples before the beginning of diet specific to their groups, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet
• Change in creatinin level in urine samples [ Time Frame: 3 weeks ] [ Designated as safety issue: No ]
  Creatinin was measured in 24-hour collected urine samples before the beginning of diet specific to their groups, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet.
• Change in microalbumin level in urine samples [ Time Frame: 3 weeks ] [ Designated as safety issue: No ]
  Microalbumin was measured in 24-hour collected urine samples before the beginning of diet specific to their groups, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet
• Change in aldosterone level in urine samples [ Time Frame: For 3 times in 8 weeks ] [ Designated as safety issue: No ]
  Aldosterone levels was measured in in the 24-hour urine samples collected , at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet.

The present prospective, randomized, crossover study is designed to investigate the effect of salt consumption on blood pressure in hypertensive subjects.

Secondary objectives of the study are to evaluate the effect of salt consumption on blood pressure among the subjects who are hypertensive and obese and normal according to body mass index and to evaluate the effect of salt consumption on renin activity in hypertensive subjects.

The present study is carried out with the subjects who are chosen among the nursing home residents in İzmir. The subjects were randomized to 2 groups and while one of these groups had low salt diet (50mmol), the other group had normal salt diet (250mmol) for 3 weeks. Subjects had normal salt diet in their daily routine life for the following 2 weeks. According to crossover nature of the study, the group that had normal salt diet at the first 3 weeks of study had low salt diet at the last 3 weeks of the study. The other group that had low salt diet had the normal salt diet at the last 3 week of the study.

At the beginning of the study, information such as demographic, family story, medical story, diet habits, concomitant medication and physical measurements (height, weight and waist circumference) were received from the subjects.

24 hour blood pressure of the subjects is measured for four times, before the beginning of diet specific to their groups, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet. The subjects were asked for collecting 24-h urine in the same days of blood pressure measurement. Sodium, potassium, urea, creatinin and microalbumin measurements were measured in the collected urine. Blood samples were collected for three times, at the end of the 3-week diet, before the beginning of the second diet and at the end of their second diet. Plasma renin activity and aldosterone levels were measured in the blood samples collected. Aldosterone level was measured in the 24-hour urine in mentioned days.

• No Intervention: Normal salt diet
  The group had normal salt diet (250mmol)for three weeks. Subjects had normal salt diet in their daily routine life for the following 2 weeks.According to crossover nature of the study, the group had low salt diet (50mmol) at the last 3 weeks of the study.
• Experimental: Low salt diet
  The group had low salt diet (50mmol)for three weeks. Subjects had normal salt diet in their daily routine life for the following 2 weeks.According to crossover nature of the study, the group had normal salt diet at the last 3 weeks of the study.
  Intervention: Behavioral: Lowering salt in diet

Inclusion Criteria:

• Subjects who are 50 years and older
• Subjects whose systolic blood pressure is ≥ 140 mmHg
• Subjects whose diastolic blood pressure is ≥ 90 mmHg
• Subjects who is normal weighted defined as body mass index < 25 or who is obese defined as body mass index > 30
• Subjects who have intellectual capacity to adapt diets and 24 hour urine collection
• Informed about the study and consented to include the study

Exclusion Criteria:

• Known heart failure
• Known renal failure
• Known chronic liver disease
• Antihypertensive drug use
• nonsteroidal anti inflammatory (NSAI) drug use