Kidney stones: don't curb the calcium.It starts off innocuously, as a microscopic crystal floating in the tubules of the kidney, Over time, though, such invisible particles can grow layer upon layer, ultimately forming painful kidney stones Kidney Stones Definition
Kidney stones are solid accumulations of material that form in the tubal system of the kidney. Kidney stones cause problems when they block the flow of urine through or out of the kidney. that afflict af·flict
tr.v. af·flict·ed, af·flict·ing, af·flicts
To inflict grievous physical or mental suffering on.
[Middle English afflighten, from afflight, one in nine people in the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. at some point in their lives. Because most kidney stones are made of calcium, physicians often recommend that patients who have already suffered from stones reduce their calcium intake. But a new study of more than 45,000 men challenges the traditional thinking, suggesting that low-calcium diets actually raise the risk of developing kidney stones.
In the March 25 NEW ENGLAND JOURNAL OF MEDICINE The New England Journal of Medicine (New Engl J Med or NEJM) is an English-language peer-reviewed medical journal published by the Massachusetts Medical Society. It is one of the most popular and widely-read peer-reviewed general medical journals in the world. , a research team from the Harvard School of Public Health The Harvard School of Public Health is (colloquially, HSPH) is one of the professional graduate schools of Harvard University. Located in Longwood Area of the Boston, Massachusetts neighborhood of Mission Hill, next to Harvard Medical School and Cambridge, Massachusetts, reports that men who ate a diet rich in calcium faced a 34 percent lower risk of developing kidney stones than did men who consumed a restricted calcium diet.
"This goes against everything we had been taught," says kidney specialist Gary C. Curhan, who led the calcium investigation. Curhan and his colleagues took their data from the Health Professionals Follow-up Study, a long-term investigation of diet and illness among male health care professionals age 40 through 75.
While it seems counterintuitive coun·ter·in·tu·i·tive
Contrary to what intuition or common sense would indicate: "Scientists made clear what may at first seem counterintuitive, that the capacity to be pleasant toward a fellow creature is ... that consuming calcium could protect against calcium-based kidney stones, Curhan thinks that a chemical called oxalate oxalate /ox·a·late/ (ok´sah-lat) any salt of oxalic acid.
A salt or ester of oxalic acid. may explain the apparent puzzle, Oxalate is present in many foods, and it combines with calcium to form the insoluble insoluble /in·sol·u·ble/ (in-sol´u-b'l) not susceptible of being dissolved.
Not soluble. crystals that make up most kidney stones.
Curhan suggests that a normal diet might provide enough calcium to tie up oxalate in the intestines, creating crystals that pass directly out of the body without harm. But a low-calcium diet would allow more oxalate to enter the bloodstream and eventually reach the kidneys, where it can form the crystals that lead to kidney stones.
That doesn't mean people should head to the local market and raid the dairy case with abandon. "The important thing we're trying to emphasize is not that adding calcium is necessarily going to help you but that for someone who has already had a stone, restricting calcium is not the right thing to do," says Curhan. He suggests people consume the recommended 800 milligrams per day.
He stresses that increasing fluid in-take substantially cuts the risk of stones. The new study also hints that potassium may protect against developing stones: Men who ate a potassium-rich diet faced a 50 percent lower risk than did those who consumed the least amount of potassium.