[PHNUTR-L] New Data on Dietary Protein and Bone

[Desire' Stapley]

STORY LEAD:
New Data on Dietary Protein and Bone 

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ARS News Service
Agricultural Research Service, USDA
Rosalie Marion Bliss, (301) 504-4318, rbliss at ars.usda.gov
April 28, 2003
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A high-protein diet containing mostly meat did not have adverse effects on
women's ability to retain calcium in a study conducted by Agricultural
Research Service scientists in Grand Forks, N.D.

ARS researchers Zamzam Roughead and Janet Hunt at the Grand Forks Human
Nutrition Research Center controlled the diets of 15 healthy
postmenopausal women, providing both low- and high-meat diets for eight
weeks each. The women consumed about 600 milligrams (mg) of calcium per
day, half the recommended intake of 1,200 mg. Calcium, sodium and caffeine
intakes were kept constant.

In recent years, scientists have theorized that high-protein diets leach
calcium from bones, leading to bone loss, based on findings from tests
involving purified proteins. But unlike purified proteins, meat contains
substantial amounts of potassium and phosphorus, which reduce urinary
calcium loss. About 200 million people worldwide are affected by the bone
thinning known as osteoporosis.

In the study, after the first four weeks of each eight-week phase, the
scientists tracked calcium levels using body count technology that detects
differences in calcium retention and excretion. The scientists found that
even with low-but-average calcium intake, the volunteers could eat twice
the recommended dietary allowance of protein, mostly as meat, and not have
an adverse effect on calcium retention or on biomarkers for bone
breakdown.

The high-meat diet consisted of 20 percent of daily calories as protein,
or about 117 grams, including 10.5 ounces of meat. The low-meat diet
consisted of 12 percent protein, including 1.5 ounces of meat. While
eating as much as 35 percent of daily calories as protein is considered
safe, the study was designed to give no more than 20 percent of daily
calories as protein to ensure that volunteers consumed a varied diet.

The study was published in the April issue of the Journal of Nutrition.

The scientists next will launch confirmational studies, including one to
corroborate other findings that high-protein diets, in combination with
the recommended 1,200 mgs of daily calcium, may benefit bones.

ARS is the chief scientific research agency of the U.S. Department of
Agriculture.

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Desiré H Stapley, RD, LD
Technical Information Specialist
ARS/USDA/Food and Nutrition Information Center
National Agricultural Library
10301 Baltimore Ave, Rm 105
Beltsville, MD 20705
301-504-6366
dstapley at nal.usda.gov

http://www.nal.usda.gov/fnic/