Effect of Sodium Intake on Calcium Retention in Girls

This study has been completed.
Sponsor:
Collaborator:
Institute of Child Health
Information provided by (Responsible Party):
Purdue University
ClinicalTrials.gov Identifier:
NCT01564238
First received: February 2, 2012
Last updated: April 3, 2012
Last verified: April 2012
  Purpose

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.


Condition Intervention
Osteoporosis
Other: Low Na diet (1.3 g/d)
Other: High sodium diet (3.8 g/d)

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single Blind (Subject)
Primary Purpose: Prevention
Official Title: Effect of Sodium Intake on Calcium Retention in Black and White Adolescent Girls.

Resource links provided by NLM:


Further study details as provided by Purdue University:

Primary Outcome Measures:
  • Change in calcium retention(mg/d)due to high (4g/d) and low (1g/d) sodium intake. [ Time Frame: Up to 12 weeks ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Potassium retention in the black and white adolescent subjects [ Time Frame: Up to 12 weeks ] [ Designated as safety issue: No ]
  • Racial differences on the effects of high and low sodium intake levels on calcium intake requirements and calcium retention in adolescent girls [ Time Frame: Up to 12 weeks ] [ Designated as safety issue: No ]
  • Magnesium retention in the black and white adolescent subjects [ Time Frame: Up to 12 weeks ] [ Designated as safety issue: No ]

Enrollment: 67
Study Start Date: June 1999
Study Completion Date: August 2000
Primary Completion Date: August 2000 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: High calcium diets (1300 mg or higher) Other: Low Na diet (1.3 g/d)
20 day controlled feeding study (live in) providing 1.3 grams per day of sodium.
Other Names:
  • low sodium
  • sodium calcium
Other: High sodium diet (3.8 g/d)
20 day controlled feeding study (live in) providing 3.8 grams per day of sodium.
Other Names:
  • high sodium
  • sodium calcium
Experimental: Low calcium diet (800 mg/d) Other: Low Na diet (1.3 g/d)
20 day controlled feeding study (live in) providing 1.3 grams per day of sodium.
Other Names:
  • low sodium
  • sodium calcium
Other: High sodium diet (3.8 g/d)
20 day controlled feeding study (live in) providing 3.8 grams per day of sodium.
Other Names:
  • high sodium
  • sodium calcium

Detailed Description:

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.

  Eligibility

Ages Eligible for Study:   11 Years to 15 Years
Genders Eligible for Study:   Female
Accepts Healthy Volunteers:   Yes
Criteria

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.
  Contacts and Locations
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Please refer to this study by its ClinicalTrials.gov identifier: NCT01564238

Locations
United States, Indiana
Purdue University
West Lafayette, Indiana, United States, 47906
Sponsors and Collaborators
Purdue University
Institute of Child Health
Investigators
Principal Investigator: Connie M Weaver, PhD Purdue University
Study Director: Berdine R Martin, PhD Purdue University
  More Information

Publications:
Additional publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Purdue University
ClinicalTrials.gov Identifier: NCT01564238     History of Changes
Other Study ID Numbers: Camp Calcium 5-6
Study First Received: February 2, 2012
Last Updated: April 3, 2012
Health Authority: United States: Institutional Review Board

Keywords provided by Purdue University:
calcium retention
sodium retention

Additional relevant MeSH terms:
Osteoporosis
Bone Diseases, Metabolic
Bone Diseases
Musculoskeletal Diseases
Calcium, Dietary
Bone Density Conservation Agents
Physiological Effects of Drugs
Pharmacologic Actions

ClinicalTrials.gov processed this record on July 23, 2014