Healthy
Conditions
Keywords
Meat protein, acid load, calcium retention, postmenopausal women
Brief summary
The impact of protein sources such as beef as part of Western diet on calcium retention remains controversial. We propose to test the hypothesis that the positive effect of high protein intake (especially from meat protein) can offset the negative effect of protein-induced net acid load on bone metabolism and the retention of body calcium. Healthy postmenopausal women recruited from the community will consume two diets differing in meat protein and acid load for 7 weeks. Calcium retention from diets will be determined using a highly sensitive measurement of whole body retention of a calcium isotope added to the diet.
Interventions
OTHERHigh Meat - High Potential Renal Acid Load (PRAL) diet
Menu high in meat protein
OTHERLow Protein - Low Potential Renal Acid Load (PRAL) diet
Menu low in meat protein
Sponsors
USDA Grand Forks Human Nutrition Research Center
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
FEMALE
Age
40 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
* Average body mass index * Normal blood work * Normal bone density
Exclusion criteria
* Chronic disorder * Non-traumatic bone fractures
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Calcium Absorption | 18 weeks | After 3 weeks equilibration to the diet, the 2-day menu was extrinsically labeled with Calcium-47 radiotracer and retention was monitored for 28 days by whole body scintillation counting. Percent Calcium-47 absorbed was estimated from the y-intercept of the linear portion of a semilogarithmic plot of percent Calcium-47 retained vs time. |
Countries
United States
Participant flow
Recruitment details
Participants were recruited from the Grand Forks, North Dakota community in November and December, 2007.
Pre-assignment details
Of the 128 women who applied for the study, 56 did not meet the criteria, 46 declined, 4 were alternates, and 22 joined the study.
Participants by arm
| Arm | Count |
|---|---|
| Entire Study Population Dietary Intervention: Crossover design, High meat and high potential renal acid load (high PRAL) diet and low meat and low potential renal acid load (low PRAL) diet, consumed in random order. | 22 |
| Total | 22 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Period: First Intervention | Protocol Violation | 0 | 3 |
| Period: First Intervention | Withdrawal by Subject | 0 | 2 |
| Period: Second Intervention | Withdrawal by Subject | 1 | 0 |
Baseline characteristics
| Characteristic | Entire Study Population |
|---|---|
| Age, Continuous | 56.9 years STANDARD_DEVIATION 3.2 |
| Sex: Female, Male Female | 22 Participants |
| Sex: Female, Male Male | 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 / 20 | 0 / 19 |
| serious Total, serious adverse events | 0 / 20 | 0 / 19 |
Outcome results
Primary
Calcium Absorption
After 3 weeks equilibration to the diet, the 2-day menu was extrinsically labeled with Calcium-47 radiotracer and retention was monitored for 28 days by whole body scintillation counting. Percent Calcium-47 absorbed was estimated from the y-intercept of the linear portion of a semilogarithmic plot of percent Calcium-47 retained vs time.
Time frame: 18 weeks
Population: Analysis included only the 16 volunteers that completed both dietary interventions.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| High Meat - High Potential Renal Acid Load | Calcium Absorption | 30.4 percentage of Calcium-47 absorbed | Standard Error 2.4 |
| Low Meat - Low Potential Renal Acid Load | Calcium Absorption | 25.4 percentage of Calcium-47 absorbed | Standard Error 2.4 |
Comparison: 16 subjects required to detect a difference in Calcium 47 absorption of 2 percentage points with 90% power, alpha = 0.05p-value: 0.02Mixed Models Analysis