ORIGINAL COMMUNICATION Relationship of urinary sodium=potassium excretion and calcium intake to blood pressure and prevalence of hypertension among older Chinese vegetarians

Objective: To examine the associations of dietary sodium and potassium, as reflected by the urinary sodium=potassium excretion, and calcium intake with blood pressure and the prevalence of hypertension among older Chinese vegetarians in Hong Kong. Design: Cross-sectional study. Setting: Research clinic in a teaching hospital in Hong Kong. Subjects: A total of 111 ambulatory vegetarians over the age of 55 were recruited from members of religious organizations or old age hostels. Main outcome measures: Hypertension was defined as supine blood pressure > 140=90 mmHg or a history of hypertension. Dietary sodium, potassium and calcium intakes were assessed by 24 h recall method or fasting urinary sodium or potassium= creatinine ratios. Results: Seventy-one subjects (64%) were found to have hypertension. Compared with normotensive subjects, hypertensive subjects had lower calcium intake (411 s.d. 324 vs 589 428 mg, P1⁄40.04), but higher urinary sodium=creatinine ratio (32.6 19.3 vs 21.0 12.4, P1⁄4 0.00) and sodium=potassium ratio (4.7 2.8 vs 3.4 2.3, P1⁄40.02). Among 88 subjects not taking diuretics or antihypertensive drugs, systolic blood pressure was related to calcium intake (r1⁄4 70.40), urinary sodium=creatinine ratio (r1⁄40.39), urinary sodium=potassium ratio (r1⁄40.30) and age (r1⁄40.23). Diastolic blood pressure was related to urinary sodium=creatinine (r1⁄40.29). Twenty-three subjects with high urinary sodium=potassium and low calcium intake and 16 subjects with low urinary sodium=potassium ratio and high calcium intake differed markedly with respect to systolic blood pressure (159 26 vs 130 15 mmHg) and prevalence of hypertension (78% vs 25%). Conclusions: Older Chinese vegetarians are predisposed to hypertension because of their sodium-rich but calcium-deficient diets. European Journal of Clinical Nutrition (2003) 57, 299 – 304. doi:10.1038=sj.ejcn.1601553