81,093 women between the ages of 40 - 65, who reported no incidence
of kidney stones when the study commenced in 1986, participated
in the Nurses' Health Study.Their average use of 131 specified
foods and beverages in 1985 and again in 1990 was recorded. Daily
intakes of nutrients, fluid and calcium were then calculated from
the data, and adjustments made for risk factors other than fluid
intake.
719 cases of kidney stones were documented over the 8 year follow
up. It was found that all liquids, including coffee and alcohol,
decreased the risk for stone formation by the following percentage
per 240ml serving consumed daily: 10% for coffee, 8% for tea and
by 59% for wine. In contrast, each serving of grapefruit juice increased the
risk of stone formation by 44%.
The study concluded that an increase in total fluid intake can
reduce the risk for kidney stones, and the choice of beverage
may be important. Alcohol inhibits secretion of antidiuretic hormone,
leading to increased urine flow and hence stronger dilution helping
kidney stone sufferers as well as acting as a preventative.These
results may not necessarily apply only to women.
