Systolic blood pressure salt intake

In 2002, the British Medical Journal published a review of eleven trials of interventions aimed at reducing dietary salt intake. Tens of thousands of subjects were involved, with and without hypertension. Follow-up ranged from six months to seven years, comparing the blood pressure reductions of people following the advice of salt restriction with those in the control groups, people not given that advice. The average difference was a mere 1.1 mm Hg systolic blood pressure and 0.6 mm Hg diastolic. 

Blood pressure, especially systolic pressure, increases with age in Western countries and in most cultures in which salt intake is high. In women, the increase is more marked after age 50. Although treated conservatively in the past, most clinicians now believe that hypertension should be treated vigorously in the elderly. 

Recall that the dependent variable is the one that is observed to determine if it is affected by changes in the independent variable. The dependent variable in this experiment was systolic pressure. You can see that in this case, an increase in salt intake corresponds to an increase in systolic pressure. These data support the hypothesis that increases in salt intake cause a rise in blood pressure. 

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