Effect of Sodium Intake on Calcium Retention in Girls

May 3, 2018 updated by: Berdine Martin, Purdue University

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.

Study Overview

Status

Completed

Conditions

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.

Study Type

Interventional

Enrollment (Actual)

67

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Indiana
      • West Lafayette, Indiana, United States, 47906
        • Purdue University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

11 years to 15 years (Child)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

Female

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: High calcium diets (1300 mg or higher)
20 day controlled feeding study (live in) providing 1.3 grams per day of sodium.
Other Names:
  • low sodium
  • sodium calcium
20 day controlled feeding study (live in) providing 3.8 grams per day of sodium.
Other Names:
  • sodium calcium
  • high sodium
Experimental: Low calcium diet (800 mg/d)
20 day controlled feeding study (live in) providing 1.3 grams per day of sodium.
Other Names:
  • low sodium
  • sodium calcium
20 day controlled feeding study (live in) providing 3.8 grams per day of sodium.
Other Names:
  • sodium calcium
  • high sodium

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Change in calcium retention(mg/d)due to high (4g/d) and low (1g/d) sodium intake.
Time Frame: Up to 12 weeks
Up to 12 weeks

Secondary Outcome Measures

Outcome Measure
Time Frame
Potassium retention in the black and white adolescent subjects
Time Frame: Up to 12 weeks
Up to 12 weeks
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
Up to 12 weeks
Magnesium retention in the black and white adolescent subjects
Time Frame: Up to 12 weeks
Up to 12 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Study Director: Berdine R Martin, PhD, Purdue University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

January 1, 1999

Primary Completion (Actual)

August 1, 2000

Study Completion (Actual)

August 1, 2000

Study Registration Dates

First Submitted

February 2, 2012

First Submitted That Met QC Criteria

March 23, 2012

First Posted (Estimate)

March 27, 2012

Study Record Updates

Last Update Posted (Actual)

May 9, 2018

Last Update Submitted That Met QC Criteria

May 3, 2018

Last Verified

May 1, 2018

More Information

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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