This pilot randomized controlled trial evaluated the effects of the Dietary Approaches to Stop Hypertension (DASH) diet and lifestyle modification on blood pressure in adults with prehypertension. The study was conducted among adults aged 20-64 years who were diagnosed with prehypertension based on one-week blood pressure monitoring.

A total of 32 participants were randomly assigned to one of three groups: verbal lifestyle modification advice, DASH diet, or DASH diet combined with lifestyle modification. Participants were followed for 2 months. Blood pressure measurements were repeated at the end of the first and second months. Dietary intake, anthropometric measurements, body composition, physical activity records, and routine biochemical parameters were also assessed during the study.

This pilot randomized controlled trial was conducted to evaluate the effects of the Dietary Approaches to Stop Hypertension (DASH) diet and lifestyle modification on blood pressure in adults with prehypertension.

The study was carried out at the Internal Medicine Outpatient Clinic of Antalya Atatürk State Hospital between March 2015 and April 2015. Adults aged 20-64 years who were diagnosed with prehypertension after one week of blood pressure monitoring were included. Prehypertension was defined according to the Seventh Report of the Joint National Committee criteria as systolic blood pressure of 120-139 mmHg and/or diastolic blood pressure of 80-89 mmHg. All participants provided written informed consent before enrollment.

A total of 32 eligible participants were randomly assigned to one of three intervention groups. The first group received verbal advice on lifestyle modification, including reducing salt intake, avoiding salted foods, weight loss when body mass index was 25 kg/m² or higher, regular aerobic physical activity, and limiting alcohol consumption. The second group received an individualized DASH diet plan. For this group, resting metabolic rate and total energy requirements were calculated, and dietary plans were prepared according to the recommended DASH food group servings. The third group received both an individualized DASH diet and lifestyle modification recommendations. In this group, energy requirements for participants with body mass index of 25 kg/m² or higher were calculated according to desirable body weight, and sodium intake was controlled by providing measured daily salt amounts according to DASH recommendations.

Participants were followed for 2 months. Blood pressure measurements were performed at baseline and repeated at the end of the first and second months. Blood pressure was measured in a seated position after a 5-minute rest, with attention to avoiding smoking, caffeine, alcohol, and physical activity before measurement.

Data collection included demographic characteristics, smoking and alcohol use, physical activity status, medication and supplement use, anthropometric measurements, body composition, dietary intake, blood pressure, and routine biochemical parameters. Dietary intake was assessed using 3-day 24-hour food records at baseline, at the end of the first month, and at the end of the second month. Food frequency data were also collected at baseline and at the end of the study. Anthropometric measurements and body composition analyses were performed at baseline and at the end of the second month. Routine biochemical and hematological parameters were obtained from patient records at baseline and at the end of the second month. Physical activity was assessed using 24-hour physical activity records.

The primary purpose of the study was to compare the effects of lifestyle modification advice, the DASH diet, and the DASH diet combined with lifestyle modification on systolic and diastolic blood pressure in adults with prehypertension over a 2-month follow-up period.

Inclusion Criteria:

• Adults aged 20 to 64 years
• Diagnosis of prehypertension based on one-week blood pressure monitoring
• Systolic blood pressure between 120 and 139 mmHg and/or diastolic blood pressure between 80 and 89 mmHg
• Willingness to participate in the study voluntarily
• Provision of written informed consent

Exclusion Criteria:

• Presence of kidney disease
• Pregnancy
• Lactation
• Diagnosis of cancer
• Use of vitamin or mineral supplements
• Performing more than 150 minutes of physical activity per week

Individual participant data will not be shared.

No masking was used. Participants and investigators were aware of the assigned intervention because the study involved dietary and lifestyle modification interventions.