On the basis of available data, an Institute of Medicine committee set an Adequate Intake for potassium at 4.7g/day (120 mmol/day) for adults. This level of dietary intake should maintain lower blood pressure levels, reduce the adverse effects of salt on blood pressure, reduce the risk of kidney stones, and possibly decrease bone loss. Current dietary intake of potassium is considerably lower than this level.
Humans evolved on a diet that was rich in potassium and bicarbonate precursors and low in salt. However, contemporary Western-style diets have the opposite pattern—that is, relatively low content of potassium and high content of salt. Based on intake data from the Third National Health and Nutrition Examination Survey (NHANES-III,1988-1994), the percentage of men and women who consumed equal to or more than 4.7g/day (120mmol/day) was less than 10 and 1%, respectively. Median intake of potassium in the United States ranged from 2.8 to 3.3 g/day (72 to 84 mmol/day) for adult men and 2.2 to 2.4 g/day (56 to 61mmol/day) for adult women. The median potassium intake of non-African Americans exceeded that of African Americans. Because African Americans have a relatively low intake of potassium and a high prevalence of elevated blood pressure and salt sensitivity, this subgroup would especially benefit from an increased potassium intake.
Dietary intake surveys typically do not include estimates from salt substitutes and supplements. However, less than 10% of those surveyed in NHANES-III reported using salt substitutes or a reduced-sodium salt. Because a high dietary intake of potassium can be achieved through diet rather than pills and because potassium derived from foods also comes with bicarbonate precursors, as well as a variety of other nutrients, the preferred strategy to achieve the recommended potassium intake is to consume foods rather than supplements.
Dietary sources of potassium, as well as bicarbonate precursors, are fresh fruits, fruit juices, dried fruits, and vegetables. Although meat, milk, and cereal products contain potassium, their content of bicarbonate precursors does not sufficiently balance the amount of acid-forming precursors, such as sulfur amino acids, found in higher protein foods. The typical content of potassium-rich foods is displayed in Table 1. Salt substitutes currently available in the marketplace range from 0.4 to 2.8 g/teaspoon (11-72 mmol/teaspoon) of potassium, all as potassium chloride.
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