The primary objective is to determine whether meat interacts positively with calcium to improve calcium retention. The secondary objective is to determine whether any interaction between dietary protein and calcium affects biomarkers of bone metabolism.
This study tests the effects of dietary protein and calcium on calcium retention and indices of bone metabolism. It is a controlled feeding trial with a randomized crossover design (2x2 Factorial), studying 34 healthy post-menopausal women. The women are blocked on Body Mass Index (weight in kilograms divided by height in meters squared)and randomly assigned to a high calcium (HC,1500 milligrams per day) or low calcium (LC, 600 milligrams per day) group, and consume both low protein (LP,10% protein) and high protein (HP, 20% protein) diets for 7 weeks each. There is a 3-week "washout" between dietary periods, during which the subjects consume self-selected diets. After 3 week equilibration to each diet, the 2-day rotating menu is extrinsically labeled with a Calcium-47 radiotracer and retention is monitored for 28 days by whole body scintillation counting. In addition to Calcium retention, other endpoints include urinary indices of acid excretion and urine serum indices of bone resorption.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
34
High and low protein diets with meat as a primary protein source, tested in a cross-over design for each arm
High and low protein diets with meat as a primary protein source, tested in a cross-over design for each arm
United States Department of Agriculture (USDA) Grand Forks Human Nutrition Research Center
Grand Forks, North Dakota, United States
Calcium Absorption
Retention of Calcium-47 was monitored for 28 days by whole body scintillation counting. The percentage of Calcium-47 absorbed was estimated from the y-intercept of the linear portion of a semilogarithmic retention plot of percent Calcium-47 retained vs time
Time frame: 17 weeks
Serum Insulin-like Growth Factor 1 (IGF-1)
Time frame: 7 weeks
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