FOR RELEASE: MARCH 2004

 

INSTITUTE OF MEDICINE RELEASES NEW DIETARY REFERENCE INTAKES FOR WATER, SALT, POTASSIUM AND CHLORIDE

 

STILLWATER---The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide, says the newest report on nutrient recommendations from the Institute of Medicine of the National Academies. The report set general recommendations for water intake based on detailed national data, which showed that women who appear to be adequately hydrated consume an average of approximately 2.7 liters (91 ounces) of total water -- from all beverages and foods -- each day, and men average approximately 3.7 liters (125 ounces) daily. These values represent adequate intake levels, those who are very physically active or who live in hot climates may need to consume more water. About 80 percent of people's total water comes from drinking water and beverages -- including caffeinated beverages -- and the other 20 percent is derived from food.

The report did not offer any rule of thumb based on how many glasses of water people should drink each day because hydration needs can be met through a variety of sources in addition to drinking water. While drinking water is a frequent choice for hydration, people also get water from juice, milk, coffee, tea, soda, fruits, vegetables, and other foods and beverages as well. Moreover, it was concluded that on a daily basis, people get adequate amounts of water from normal drinking behavior -- consumption of beverages at meals and in other social situations -- and by letting their thirst guide them.

Regarding salt, healthy 19- to 50-year-old adults should consume 1.5 grams of sodium and 2.3 grams of chloride each day -- or 3.8 grams of salt -- to replace the amount lost daily on average through perspiration and to achieve a diet that provides sufficient amounts of other essential nutrients. Elevated blood pressure, which may lead to stroke, coronary heart disease, and kidney disease, is associated with sodium intake. On average, blood pressure rises progressively as salt intake increases. A tolerable upper intake level (UL) -- a maximum amount that people should not exceed -- is set at 5.8 grams of salt (2.3 grams of sodium) per day. Older individuals, African Americans, and people with chronic diseases including hypertension, diabetes, and kidney disease are especially sensitive to the blood pressure-raising effects of salt and should consume less than the UL. More than 95 percent of American men ages 31 to 50 and 75 percent of American women in this age range regularly consume salt in excess of the UL.

To lower blood pressure, blunt the effects of salt, and reduce the risk of kidney stones and bone loss, adults should consume 4.7 grams of potassium per day. However, most American women 31 to 50 years old consume no more than half of the recommended amount of potassium, and men's intake is only moderately higher. African Americans in the United States generally get less potassium than non-Hispanic whites, and because they have a higher prevalence of elevated blood pressure, increased potassium intake may have particularly significant benefits for them.