Dietary Proteins
Conditions
Keywords
Calcium retention, dietary protein, dietary calcium
Brief summary
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.
Detailed description
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.
Interventions
BEHAVIORALHigh Protein Diet
High and low protein diets with meat as a primary protein source, tested in a cross-over design for each arm
BEHAVIORALLow Protein Diet
High and low protein diets with meat as a primary protein source, tested in a cross-over design for each arm
Sponsors
National Cattlemen's Beef Association, a contractor to the Beef Checkoff
USDA Grand Forks Human Nutrition Research Center
Study design
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
FEMALE
Age
50 Years to 80 Years
Healthy volunteers
Yes
Inclusion criteria
* at least 3 years since last menses * bone mineral density equal to or greater than 2.5 standard deviations from average bone mineral density for young adults, * body mass index equal to or less than 35 kilograms/meter squared
Exclusion criteria
* taking prescription medication other than hormone replacement therapy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Calcium Absorption | 17 weeks | 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 |
Secondary
| Measure | Time frame |
|---|---|
| Serum Insulin-like Growth Factor 1 (IGF-1) | 7 weeks |
Countries
United States
Participant flow
Recruitment details
Post menopausal women willing to eat controlled diet at United States Department of Agriculture (USDA) Grand Forks Human Nutrition Research Center for 14 weeks
Pre-assignment details
Subjects were assigned to either the High or Low Calcium diets. The subjects then consumed the high and low protein diets in random order, i.e. half of the subjects consumed high protein, then low protein while the other half consumed low protein, then the high protein diet. Drop-outs were replaced.
Participants by arm
| Arm | Count |
|---|---|
| High Calcium Diet Women consumed diets containing 1500 milligrams of calcium daily | 17 |
| Low Calcium Diet Women consumed diets containing 600 milligrams of calcium daily | 17 |
| Total | 34 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Loose Stools | 1 | 1 |
| Overall Study | Protocol Violation | 1 | 1 |
| Overall Study | Withdrawal by Subject | 1 | 2 |
Baseline characteristics
| Characteristic | High Calcium Diet | Low Calcium Diet | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 1 Participants | 3 Participants | 4 Participants |
| Age, Categorical Between 18 and 65 years | 16 Participants | 14 Participants | 30 Participants |
| Age, Continuous | 57 years STANDARD_DEVIATION 5 | 58 years STANDARD_DEVIATION 6 | 57 years STANDARD_DEVIATION 5 |
| Sex: Female, Male Female | 17 Participants | 17 Participants | 34 Participants |
| Sex: Female, Male Male | 0 Participants | 0 Participants | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 17 | 0 / 17 |
| serious Total, serious adverse events | 0 / 17 | 0 / 17 |
Outcome results
Primary
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
Population: Only participants which completed both protein diet periods were included in the statistical analysis
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| High Calcium Diet | Calcium Absorption | High Protein Diet | 18.1 percentage of Calcium absorbed | Standard Deviation 2.5 |
| High Calcium Diet | Calcium Absorption | Low Protein Diet | 18.0 percentage of Calcium absorbed | Standard Deviation 2.5 |
| Low Calcium Diet | Calcium Absorption | High Protein Diet | 29.5 percentage of Calcium absorbed | Standard Deviation 2.5 |
| Low Calcium Diet | Calcium Absorption | Low Protein Diet | 26 percentage of Calcium absorbed | Standard Deviation 2.5 |
p-value: 0.05Mixed Models Analysis
Secondary
Serum Insulin-like Growth Factor 1 (IGF-1)
Time frame: 7 weeks
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) | Dispersion |
|---|---|---|---|---|
| High Calcium Diet | Serum Insulin-like Growth Factor 1 (IGF-1) | High Protein Diet | 5.23 nanomoles per liter (nmols/L) | Standard Error 0.12 |
| High Calcium Diet | Serum Insulin-like Growth Factor 1 (IGF-1) | Low Protein Diet | 4.96 nanomoles per liter (nmols/L) | Standard Error 0.12 |
| Low Calcium Diet | Serum Insulin-like Growth Factor 1 (IGF-1) | High Protein Diet | 5.07 nanomoles per liter (nmols/L) | Standard Error 0.12 |
| Low Calcium Diet | Serum Insulin-like Growth Factor 1 (IGF-1) | Low Protein Diet | 4.87 nanomoles per liter (nmols/L) | Standard Error 0.12 |