Dietary sodium intake in a sample of adult male population in southern Italy: results of the Olivetti Heart Study

Abstract

Background/objectives: To assess dietary habitual sodium intake and the association between daily sodium intake and anthropometric indices, food habits and hypertension in the sample of adult male population participating in the Olivetti Heart Study.

Subjects/methods: The study population was composed of 940 men participating in the 2002-2004 follow-up examination of the Olivetti Heart Study. Blood pressure, anthropometric indices, biochemical parameters and sodium excretion in a 24-h urine collection were measured. The frequency of consumption of selected foods was estimated by a food frequency questionnaire (FFQ) capturing the previous year data. In a subgroup of the study population (n=138), the fractional excretion of sodium was estimated by endogenous lithium clearance.

Results: Dietary sodium intake estimated by 24 h urinary excretion was 203+/-70 mmol/day. Sodium excretion was significantly lower in treated hypertensive patients and higher in overweight/obese participants when compared with normotensive and normal-weight individuals, respectively. In addition, the inverse correlation detected in normal-weight individuals (r=-0.321; P<0.05) between fractional proximal tubular sodium reabsorption and dietary sodium intake was disrupted in overweight/obese individuals (r=0.058; P=NS). The independent determinants of 24 h urinary sodium excretion were body mass index (BMI), the occurrence of antihypertensive treatment, and frequency of consumption of pasta and cold cuts.

Conclusions: Habitual salt intake in this sample of male adult population in southern Italy was well above the recommended amounts. A higher salt intake and an altered renal sodium handling were observed in overweight and obese participants. Sodium intake was only slightly reduced in hypertensive participants on pharmacological therapy.