BP ......... Na ...... Ca

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" Eur J Clin Nutr. 2003 Feb; 57(2): 299-304.

Relationship of urinary sodium/potassium excretion and calcium intake

to blood pressure and prevalence of hypertension among older Chinese

vegetarians.

Kwok TC, Chan TY, Woo J.

Department of Medicine and Therapeutics, The Chinese University of

Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong

Kong. tkwok@...

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, P=0.04), but higher urinary sodium/creatinine ratio

(32.6+/-19.3 vs 21.0+/-12.4, P=0.00) and sodium/potassium ratio

(4.7+/-2.8 vs 3.4+/-2.3, P=0.02). Among 88 subjects not taking

diuretics or antihypertensive drugs, systolic blood pressure was

related to calcium intake (r=-0.40), urinary sodium/creatinine ratio

(r=0.39), urinary sodium/potassium ratio (r=0.30) and age (r=0.23).

Diastolic blood pressure was related to urinary sodium/creatinine

(r=0.29). 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. "