CHICAGO (AP) - A new study suggests another benefit to eating oranges: Women who don't get enough vitamin C may be prone to gallbladder disease.
Though the study of 13,130 men and women doesn't say vitamin C can prevent gallbladder disease, it ''supports that hypothesis,'' said Dr. Joel Simon, the lead author and an assistant professor of medicine and epidemiology at the University of California-San Francisco.
The findings appear in Monday's Archives of Internal Medicine.
Smaller studies have found a similar association, and research has shown that vitamin C-deficient guinea pigs frequently develop gallstones. Simon theorized that the same might be true in humans.
Gallstones can form when bile, a liquid produced by the liver to help break down fats during digestion, becomes oversaturated with cholesterol. Animal studies have shown vitamin C regulates the conversion of cholesterol into bile acids, Simon said.
''We hypothesized that low levels of vitamin C may be a risk factor for human gallbladder disease as well,'' he said.
The gallbladder is a pear-shaped sac beneath the liver where bile is stored. Disease is frequently characterized by gallstones, which can grow up to an inch across and cause severe abdominal pain. Treatment may involve removal of the gallbladder.
Of the estimated 19 million Americans with gallbladder disease, two-thirds are women, Simon said. Women are believed to be more prone because the feminine hormone estrogen increases the concentration of cholesterol in the bile, and most gallstones are made of cholesterol.
Simon examined data on participants in a national health and nutrition survey conducted between 1988 and 1994. Low bloodstream levels of ascorbic acid - vitamin C's chemical name - were associated with an increased prevalence of symptomatic gallbladder disease in women, but not men.
Women with higher ascorbic acid levels and those who took vitamin C supplements were significantly less likely to have the disease.
Though no vitamin C link was noted in the men, Simon said that may be simply because there wasn't enough gallbladder disease in men to detect a statistical association.
More research is needed to examine how men might be affected and to determine if vitamin C does in fact have preventive powers, researchers said.
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