Sodium Intake and Blood Pressure in Two Polynesian Populations

The populations of the Polynesian islands Rarotonga and Pukapuka are ethnically similar but observe different economic, social and dietary habits. In Rarotonga mean blood pressure increases with age, particularly in women. In Pukapuka rise of blood pressure with age is slight and only seen in women. Blood-pressure differences between the populations are greater than are accounted for by differences in height and weight. Dietary surveys and 48-hour urine collections from subsamples indicate that sodium intake in Rarotonga is about 50 mEq a day higher than in Pukapuka. No within-population correlation between blood pressure and 24-hour urinary sodium output is demonstrable. Many differences between the two groups may explain the differences in blood pressure, but the findings are compatible with Dahl's hypothesis that higher salt intake and higher blood pressures are related.