The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate
als with diuretic-induced hypokalemia did not achieve reduction in cardiovascular events compared with diuretic-treated individuals without hypokalemia (Franse et al., 2000).
Because moderate potassium deficiency and its adverse side effects occur without hypokalemia, hypokalemia is not a sensitive indicator appropriate for use to establish adequacy.
Salt-Sensitive Blood Pressure
The extent to which blood pressure responds to changes in sodium chloride intake varies among individuals. “Salt-sensitive” blood pressure is that which varies directly with the intake of sodium chloride (Morris et al., 1999b; Weinberger, 1996). Salt sensitivity, even in those who are nonhypertensive, has been found to confer its own cardiovascular risks, including incident hypertension and cardiovascular death (Morimoto et al., 1997; Weinberger et al., 2001). Salt sensitivity occurs with greater frequency and severity in nonhypertensive African Americans than in nonhypertensive whites (Morris et al., 1999b; Price et al., 2002; Weinberger, 1996).
The expression of salt sensitivity is strongly modulated by dietary potassium intake (Morris et al., 1999b; Schmidlin et al., 1999; Luft et al., 1979). In a metabolic study of 38 healthy, nonhypertensive men (24 African Americans and 14 whites) fed a basal diet with low levels of potassium (1.2 g [30 mmol]/day) and sodium (0.7 g [30 mmol]/day), the modulating effect of potassium supplementation on the pressor effect of dietary sodium chloride loading (14.6 g [250 mmol]/day) was investigated (Morris et al., 1999b) (Figure 5-1). Before potassium was supplemented, 79 percent of the African-American men and 26 percent of the white men were termed salt sensitive, as defined by a sodium chloride-induced increase in mean arterial pressure of at least 3 mm Hg. Salt sensitivity was defined as “severe” if sodium chloride induced an increase in mean arterial pressure of 10 mm Hg or more, an increase observed only in African-American men. When dietary potassium was increased with potassium bicarbonate from 1.2 g (30 mmol)/day to 2.7 g (70 mmol)/day, over half of the African-American men, but only one-fifth of the white men, remained salt sensitive. In the African Americans with severe salt sensitivity, increasing dietary potassium to a high-normal intake of 4.7 g (120 mmol)/day reduced the frequency of salt sensitivity to 20 percent, the same percentage as that observed in white subjects when their potassium intake was increased to only 2.7 g (70 mmol)/day. In another metabolic study of 16 mostly nonhypertensive African-American subjects loaded with 14.6 g (250 mmol) of