Harvard School of Public Health
researchers report that consuming a one-ounce serving of peanuts or other nuts
(about 160 calories per serving) five or more times a week is associated with
a 25% reduced risk of cholecystectomy, or removal of the gallbladder.
Consuming a half-serving, or one tablespoon, of peanut butter (about 95
calories) five or more times a week is associated with a 15% reduced risk.
Small, daily servings of peanuts and peanut butter have previously been shown
to reduce the risk of heart disease and type 2 diabetes as well. This
important study is published in the July 2004 issue of American Journal of
Although gallstone disease is a major source of morbidity in developed
countries, little attention has been given to how specific foods affect this
In Western populations, an estimated 80% of gallstones are
cholesterol stones. Gallstones are associated with high triglyceride levels
and low "good" HDL cholesterol levels, which are also risk factors for heart
In the study, researchers observed an apparent "threshold effect" of
peanut, peanut butter and nut consumption. A significant reduction in risk of
cholecystectomy was observed only in women who ate nuts or peanut butter
almost daily. Despite being calorie-dense, this study and others show that
frequently consuming peanuts, peanut butter, and nuts does not increase body
Frank Hu, MD, PhD, Associate Professor of Nutrition and
Epidemiology at Harvard School of Public Health and an author of the study
writes in the paper, " ... the women who consumed more nuts tended to weigh
less. This indicates that the energy contained in nuts tends to be balanced
by decreased intakes of other sources of energy or by increased physical
Food frequency questionnaires show how many women were eating "nuts" five
or more times per week. Of the 83,000 female nurses who were followed for an
average of 16 years in the Nurses' Health Study, 749 women ate peanut butter
almost daily compared to 82 for peanuts and 32 for other nuts.
The paper states that in addition to the well-documented benefits of
healthy mono- and polyunsaturated fats in peanuts and nuts, other bioactive
components may play a role.
Peanuts and nuts are rich sources of dietary
fiber, which may contribute to reducing the risk of gallstones by improving
insulin sensitivity and decreasing recirculation of bile acids. A one-ounce
serving of peanuts contains about two and a half grams of fiber.
Peanuts, nuts and peanut butter are rich sources of magnesium, which also
could explain the reduction in risk of cholecystectomy.
The paper suggests
that dietary magnesium plays a role in improving insulin sensitivity, thereby
reducing the occurrence of gallstones. They also contain phytosterols, which
may help lower blood cholesterol, and help reduce the risk of gallstones.
This study was supported by research grants from the National Institutes
of Health. The Peanut Institute is a non-profit organization that supports
nutrition research and develops educational programs to encourage healthful
For more information on peanuts and health, visit
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