Background: Blood pressure is influenced by psychosocial (stress), genetic, age, gender, nutritional status, and lifestyle (diet, lack of fiber consumption, smoking, lack of physical activity). 30 ml of young coconut water contains 61 mg of potassium, 5.45 mg of sodium, and 1.3 mg of sugar, affecting blood pressure changes. Coconut water contains K minerals and is useful for lowering blood pressure. Whereaswatermelon contains anti-hypertensive content, namely sodium, beta carotene, and potassium. Watermelon is rich in water, amino acids, L-arginine, which can maintain healthy blood pressure.

Aim: This study aims to determine the effect of young coconut water and watermelon juice on blood pressure in the 2013 nursing students of Respati University Yogyakarta.

Methods: This type of research is a quasi-experimental design with a nonequivalent control group pre and post-test. The sample was taken by simple random sampling, namely the control group (18 respondents), the young coconut water group (18 respondents), and papaya juice (18 respondents). Data pre-posttest of each group was tested using Paired T-test. The comparison control-treatment group was tested using an independent-test.

Results: The mean differences of systole and diastole pre-posttest blood pressure in the control group were -1.8 mmHg and -1.0 mmHg. The mean difference in systole blood pressure and the pre-posttest diastole of young coconut water groups were -3.1mmHg and -2.4 mmHg. The mean systole and diastole blood pressure in the pre-posttest watermelon juice group were -2.9 mmHg and -1.5 mmHg. The pre-posttest results of systole and diastole blood pressure analysis in the p-value control group were 0.100 and 0.450. The pre-post test results of systole and diastole blood pressure analysis of young coconut water groups gained p-value of 0.030 and 0.194. The pre-post test results of the juice watermelon group's systole and diastole blood pressure analysis gained p-value of 0.032 and 0.181. The posttest results of systole and diastole blood pressure analysis in the control group and young coconut water gained p-value of 0.014 and 0.157. The post-test results of the systole and diastole blood pressure analysis control group and juice watermelon gained p-value of 0.013 and 0.420.

Conclusion: Consumption of young coconut water and watermelon juice affects systole blood pressure, but it does not affect diastole blood pressure in nursing students in 2013 in Respati University Yogyakarta.

Keyword: Blood pressure, Coconut Water, Watermelon Juice