You don’t hear much about potassium in the world of nutrition, but it played a sizable role in last week’s report from the National Academy of Sciences, which among other things, overturned the commonly held advice to drink eight glasses of water per day for good health.
The report also urged Americans to eat a healthy amount of salt. For most, that will mean reducing what is currently consumed.
The NAS report said that potassium intake hovers around 3 grams per day — that’s about half the adequate daily intake the NAS set at 4.7 grams.
Skimping on potassium-rich food is a bad idea because research suggests that this level of potassium helps lower blood pressure and can blunt the effects of the high-salt diets.
Plus, there’s strong evidence that potassium helps protect bones and appears to reduce the risk of kidney stones.
"An increased intake of potassium would not only lead to lower sodium intake but tends to help mute the effects of sodium in the diet," said Paul Whelton, an NAS committee member and senior vice president of academic affairs at Tulane University.
"It’s a win-win situation and is especially important for certain subgroups of the population who have a disproportionate burden of illness and seem particularly sensitive to high salt and low potassium."
The report also suggests:
Doing so is more than enough to stay adequately hydrated, the report found.
"We don’t offer any rule of thumb based on how many glasses of water people should drink each day because our hydration needs can be met through a variety of sources in addition to drinking water," said Lawrence J. Appel, chairman of the panel that wrote the report and professor of medicine at Johns Hopkins Medical Institutions in Baltimore.
Water has the advantage of being calorie-free, but the report said that coffee, tea, juice, alcohol and fluid-filled food such as soups can count toward total daily fluid intake — about 16 cups per day for most men; 11 cups per day for women.
But don’t count ‘em: Drink when you’re thirsty.
In addition to all their other good qualities — fiber, vitamins, antioxidants, complex carbohydrates, water and flavor, plus being low in calories — fruit and vegetables are also a prime source of potassium.
The report notes that the potassium from fruit and vegetables helps produce bicarbonate, which acts as a buffer to neutralize acids from meat and other high-protein food. That, in turn, helps preserve bone and reduces the risk of kidney stones.
The good news: No need to pay top dollar for fresh. Frozen, dried and canned (preferably low- or reduced-sodium, of course) vegetables and fruit have amounts of potassium equal to fresh.
Some top choices are bananas, orange juice, cantaloupe, spinach and avocado. Find more on how to boost fruit and vegetable intake at www.5aday.gov, run by the National Cancer Institute.
The report set 1.5 grams of sodium per day — equal to the amount found in two to three cups of many processed soups — as an adequate intake for most adults.
People who are far more active, including endurance athletes, may need more, while adults 50 to 70 years need less (1.3 grams per day). Those age 71 or older need just 1.2 grams per day, the report said.
The biggest source of sodium is not the salt shaker, but processed and restaurant food. Such fare accounts for as much as 77 percent of daily sodium intake for Americans, the NAS said.
In any case, the NAS set an upper limit for salt of 5.8 grams per day, a level routinely exceeded by 95 percent of men and 75 percent of women in the United States.
Read food labels carefully to keep sodium intake at safe levels, said Jerome D. Cohen professor of medicine at the St. Louis University School of Medicine.
And you’ll need to move decimal points, since labels list milligrams of sodium. If a label says a food has 500 milligrams that equals 0.5 grams, about a third of a day’s intake.
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