Dietary Zinc Absorption
Conditions
Keywords
dietary zinc absorption, dietary phytic acid, dietary calcium
Brief summary
This study is determine the effects of dietary calcium and phytate on zinc absorption.
Detailed description
Zinc absorption is tested from 2 days of consuming each of four diets with zinc-65 isotope, followed by retention monitoring in a whole body scintillation counter for 4 weeks. All four 4 experimental diets are tested with each subject, in randomized order, for a total of 16 weeks.
Interventions
DIETARY_SUPPLEMENTModerate Calcium, Low phytate Diet
Participants consumed diet containing 700 milligrams calcium and 440 milligrams of phytate for 4 weeks
DIETARY_SUPPLEMENTModerate Calcium, High Phytate Diet
Participants consumed diet containing 700 milligrams calcium and 1800 milligrams of phytate for 4 weeks
DIETARY_SUPPLEMENTHigh Calcium, Low Phytate Diet
Participants consumed diet containing 1900 milligrams calcium and 440 milligrams of phytate for 4 weeks
DIETARY_SUPPLEMENTHigh Calcium, High Phytate Diet
Participants consumed diet containing 1900 milligrams calcium and 1800 milligrams of phytate for 4 weeks
Sponsors
USDA Grand Forks Human Nutrition Research Center
Study design
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
FEMALE
Age
21 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Average weight for height
Exclusion criteria
* Medications other than birth control pills or hormone replacement therapy, * Pregnancy within last 6 months
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Zinc Absorption | 16 weeks | Retention of Zinc-65 was monitored for 28 days by whole body scintillation counting. The percentage of Zinc-65 absorbed was estimated from the y-intercept of the linear portion of a semilogarithmic retention plot of percent Zinc-65 retained versus time |
Countries
United States
Participant flow
Recruitment details
Women were recruited by the United States Department of Agriculture (USDA) Grand Forks Human Nutrition Research Center to participate in an out-patient feeding study in Grand Forks, North Dakota
Pre-assignment details
205 participants applied, 157 were eligible, 27 accepted invitation to attend an information meeting, 10 started study, 7 of the alternates joined study as original participants withdrew or were discharged.
Participants by arm
| Arm | Count |
|---|---|
| Entire Study Population Includes all subjects randomized to the 4 treatments. Treatments were assigned in randomized order so the number of subjects starting the study does not equal the starting number for a given treatment | 17 |
| Total | 17 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Ca/Phytate Test Meal 1 (Randomized) | Protocol Violation | 2 |
| Ca/Phytate Test Meal 1 (Randomized) | Withdrawal by Subject | 3 |
| Ca/Phytate Test Meal 3 (Randomized) | Protocol Violation | 1 |
| Ca/Phytate Test Meal 4 (Randomized) | Protocol Violation | 1 |
Baseline characteristics
| Characteristic | Entire Study Population |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 17 Participants |
| Age, Continuous | 32.7 years STANDARD_DEVIATION 9.5 |
| Sex: Female, Male Female | 17 Participants |
| Sex: Female, Male Male | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 0 / 17 |
| serious Total, serious adverse events | 0 / 17 |
Outcome results
Primary
Zinc Absorption
Retention of Zinc-65 was monitored for 28 days by whole body scintillation counting. The percentage of Zinc-65 absorbed was estimated from the y-intercept of the linear portion of a semilogarithmic retention plot of percent Zinc-65 retained versus time
Time frame: 16 weeks
Population: Analysis restricted to women who completed all 4 treatment periods
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Moderate Calcium, Low Phytate Diet | Zinc Absorption | 32.8 Percentage of Zinc-65 absorbed | Standard Error 2.3 |
| Moderate Calcium, High Phytate Diet | Zinc Absorption | 26.9 Percentage of Zinc-65 absorbed | Standard Error 2.4 |
| High Calcium, Low Phytate Diet | Zinc Absorption | 39.4 Percentage of Zinc-65 absorbed | Standard Error 2.4 |
| High Calcium, High Phytate Diet | Zinc Absorption | 26.2 Percentage of Zinc-65 absorbed | Standard Error 2.3 |
Comparison: Two-way mixed model analysis of variance was used to test for main effect of dietary calcium and phytate and their interaction. Null Hypothesis: Dietary calcium does not affect zinc absorptionp-value: 0.17Mixed Models Analysis
Comparison: Two-way mixed model analysis of variance was used to test for main effect of dietary calcium and phytate and their interaction. Null Hypothesis: Dietary Phytate does not affect zinc absorptionp-value: 0.0002Mixed Models Analysis
Comparison: Two-way mixed model analysis of variance was used to test for main effect of dietary calcium and phytate and their interaction. Null Hypothesis: Dietary calcium and dietary phytate do not affect zinc absorption. Eight women were required to detect a difference in zinc absorption of 7 percentage points with a power of 90%, alpha level of 0.05.p-value: 0.09Mixed Models Analysis