Effect of Sodium Intake on Calcium Retention in Girls
| Status: | Completed |
|---|---|
| Conditions: | Osteoporosis |
| Therapuetic Areas: | Rheumatology |
| Healthy: | No |
| Age Range: | 11 - 15 |
| Updated: | 5/11/2018 |
| Start Date: | January 1999 |
| End Date: | August 2000 |
Effect of Sodium Intake on Calcium Retention in Black and White Adolescent Girls.
Optimal calcium retention is important for building bone mass within the genetic potential, a
key to reducing risk of osteoporosis later in life. Calcium retention is high during the
rapid growth period. The investigators know that urinary calcium is affected by sodium intake
but the investigators do not know the effects of sodium intake during the growth spurt or the
differences in calcium retention between blacks and whites. Our hypothesis was that a high
dietary sodium increases the calcium intakes required for optimal calcium retention in both
black and white adolescent girls. The investigators tested calcium retention while girls
consumed a low and high sodium diet during three week periods. The subjects were housed in a
Purdue fraternity house during the summer and they were supervised at all times by trained
staff. During the summer of 1999, subjects consumed diets with 2 levels of dietary Na+ with a
fixed diet low in calcium. On the next summer, they switched to a high calcium diet. Subjects
collected fecal and urine daily for 20 days. Other measurements included daily body weight,
blood pressure every other day, blood sample at the end of each session. Baseline measures
included bone mass, self-assessment of pubertal development, a physical examination and diet
history.
key to reducing risk of osteoporosis later in life. Calcium retention is high during the
rapid growth period. The investigators know that urinary calcium is affected by sodium intake
but the investigators do not know the effects of sodium intake during the growth spurt or the
differences in calcium retention between blacks and whites. Our hypothesis was that a high
dietary sodium increases the calcium intakes required for optimal calcium retention in both
black and white adolescent girls. The investigators tested calcium retention while girls
consumed a low and high sodium diet during three week periods. The subjects were housed in a
Purdue fraternity house during the summer and they were supervised at all times by trained
staff. During the summer of 1999, subjects consumed diets with 2 levels of dietary Na+ with a
fixed diet low in calcium. On the next summer, they switched to a high calcium diet. Subjects
collected fecal and urine daily for 20 days. Other measurements included daily body weight,
blood pressure every other day, blood sample at the end of each session. Baseline measures
included bone mass, self-assessment of pubertal development, a physical examination and diet
history.
Optimal calcium retention is a prerequisite for building maximal peak bone mass within the
genetic potential, a key to reducing risk of osteoporosis later in life. The investigators
have determined that maximal calcium retention averages 423 mg/day during the period of rapid
skeletal accretion in white girls at a mean dietary calcium intake of 1300 mg/d. Urinary
calcium explains more than 50% of the variance in calcium retention. However, urinary sodium
(i.e. sodium intake)is a major determinant of urinary calcium excretion and the effect of
sodium intake on maximal calcium retention is not known. Nor is its effect known in black
adolescents who have higher bone density and lower calcium excretion than white adolescents.
The primary aim was to test the hypothesis that high dietary sodium increases the calcium
intakes required for optimal calcium retention in both black and white adolescent girls.
Calcium retention was measured at two levels of dietary sodium in a randomized crossover
design on one of two levels of dietary calcium intake in black and white adolescent girls
during three week metabolic periods. The investigators hypothesized that the mechanisms which
regulate sodium reabsorption in the renal tubules also regulate calcium retention. Increased
incidence of hypertension in blacks compared to whites has been attributed to increased
sodium retention. Sodium intake induced changes in calcium and sodium retention in both races
were related to changes in sodium handling (plasma renin activity, serum aldosterone, and
salt sensitivity) and calcium regulating hormones, biomarkers of bone turnover and bone mass.
The subjects were resident in a Purdue fraternity house, which was transformed during the
summer into a metabolic unit. Subjects were supervised at all times by trained staff. The
balance study was divided into 2 sessions of 3 weeks each during the summer of 1999 and 2000,
with 2 levels of dietary Na+ during each summer. During the summer of 1999 subjects consumed
a low calcium diet while in the summer of 2000 subjects consumed a high calcium diet. The Na+
intake periods were separated by a 2-week period, in which subjects were free to consume
self-selected diets. Subjects collected fecal and urine daily for 20 days. Other measurements
included daily body weight, blood pressure every other day, blood sample at the end of each
session. Baseline measures included bone mass, self-assessment of pubertal development, a
physical examination and diet history.
genetic potential, a key to reducing risk of osteoporosis later in life. The investigators
have determined that maximal calcium retention averages 423 mg/day during the period of rapid
skeletal accretion in white girls at a mean dietary calcium intake of 1300 mg/d. Urinary
calcium explains more than 50% of the variance in calcium retention. However, urinary sodium
(i.e. sodium intake)is a major determinant of urinary calcium excretion and the effect of
sodium intake on maximal calcium retention is not known. Nor is its effect known in black
adolescents who have higher bone density and lower calcium excretion than white adolescents.
The primary aim was to test the hypothesis that high dietary sodium increases the calcium
intakes required for optimal calcium retention in both black and white adolescent girls.
Calcium retention was measured at two levels of dietary sodium in a randomized crossover
design on one of two levels of dietary calcium intake in black and white adolescent girls
during three week metabolic periods. The investigators hypothesized that the mechanisms which
regulate sodium reabsorption in the renal tubules also regulate calcium retention. Increased
incidence of hypertension in blacks compared to whites has been attributed to increased
sodium retention. Sodium intake induced changes in calcium and sodium retention in both races
were related to changes in sodium handling (plasma renin activity, serum aldosterone, and
salt sensitivity) and calcium regulating hormones, biomarkers of bone turnover and bone mass.
The subjects were resident in a Purdue fraternity house, which was transformed during the
summer into a metabolic unit. Subjects were supervised at all times by trained staff. The
balance study was divided into 2 sessions of 3 weeks each during the summer of 1999 and 2000,
with 2 levels of dietary Na+ during each summer. During the summer of 1999 subjects consumed
a low calcium diet while in the summer of 2000 subjects consumed a high calcium diet. The Na+
intake periods were separated by a 2-week period, in which subjects were free to consume
self-selected diets. Subjects collected fecal and urine daily for 20 days. Other measurements
included daily body weight, blood pressure every other day, blood sample at the end of each
session. Baseline measures included bone mass, self-assessment of pubertal development, a
physical examination and diet history.
Inclusion Criteria:
- White or black race (both parents and grandparents had to be white or black to be
eligible in the study).
Exclusion Criteria:
- < 11 or > 15 years
- body mass index (BMI) of < 15th or > 85th percentile for age
- history of amenorrhea, pregnancy or abortion, eating disorders, oral contraceptive or
tobacco use.
We found this trial at
1
site
Click here to add this to my saved trials
