Relationship between salt intake, salt-taste threshold and blood pressure in Nigerians.

Background: Many studies have found an association between sodium intake and blood pressure. Salt taste threshold is thought to be another marker of sodium intake.

Objective: This study sought to assess two markers of sodium intake, 24-hour-urinary sodium and salt-taste threshold. We also determined the relationship between these two markers and blood pressure.

Methods: Salt taste threshold was measured by the ability of the subjects to discern the taste of salt in graded solutions of saline. Twenty-four urinary sodium was measured by flame photometry in a 24-hour urine collection. Other plasma and urine electrolytes and creatinine were measured using standard automated chemistry methods.

Results: There was a significantly higher salt intake measured as 24-hour urinary sodium/mmol of creatinine in the hypertensive group, (36.6±20mmol/L/mmol creatinine) compared with the normotensive group (14.8±5.8mmol/L/mmol creatinine) p<0.001. Urinary potassium was also higher in the hypertensive subjects. When the subjects were grouped into low and high salt taste threshold, the high salt threshold group also had significantly higher 24 hour urinary sodium (30.3±5mmol/L creatinine vs the low STT urinary sodium of (19.5±14 p <.05).

Conclusion: Sodium intake measured as 24-hour urinary sodium is increased in subjects with hypertension attesting to sodium intake as a risk factor for the development of high blood pressure. Subjects with high salt taste threshold also have increased urinary sodium excretion which may predispose them to development of hypertension.