Clinical trial NCT00671944: Long-term Nutritional Intervention Study to Determine How Protein Affects Calcium Metabolism
Official title: Long-term Impact of Protein on Calcium Kinetics
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE1
Conditions: Osteoporosis
Keywords: protein
calcium
parathyroid hormone
bone markers
calcium kinetics
absorption
Lead sponsor: Yale University
Sponsor class: OTHER
Collaborators: name: United States Department of Agriculture (USDA)
First posted: 2008-05-05
Enrollment: 11
Sex: FEMALE
Minimum age (years): 20
Maximum age (years): 40
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: Osteoporosis is a major health problem in men and women in this country and the incidence of this disease is rising. We think that environmental factors such as nutrition may play a role in the increasing prevalence of osteoporosis. In particular, we think that a diet that is too low in protein may be contributing to bone loss. The primary purpose of this study is to compare the long-term impact of a low protein diet on measures of bone and calcium metabolism.

Detailed description: The protocol is composed of a 9.5-week study, consisting of a 3-week adjustment period followed by a 6.5-week experimental period. During the adjustment period, subjects consume a well-balanced lead-in diet designed to stabilize baseline Ca homeostasis. In the subsequent experimental period, subjects will consume the experimental diet containing 0.7 g protein/kg, 800-1200 mg phosphorus, 800 mg calcium and 2300 mg sodium. During days -6 to -1 of the adjustment diet, 5-10 and days 40-45 of the experimental period, we will measure Ca absorption and kinetics. Weekly assessments of Ca homeostasis will be done using our standard measures of calcitropic hormones, markers of bone turnover, and urine and serum minerals.

Eligibility criteria: Inclusion Criteria:

* Healthy Asian or Caucasian women between the ages of 20-40 years.

Exclusion Criteria:

* Diseases or medical conditions: gastrointestinal diseases, osteoporosis, diabetes, hypertension, liver disease, thyroid disorders, kidney disease, kidney stones, cancer, heart disease, eating disorders, obesity, hypogonadism , amenorrhea, oligomenorrhea, abnormal serum FSH or estradiol levels, birth control medication, or other hormone-altering medications, pregnancy.
* Lifestyle: smoking, excessive exercise (although moderate exercise is allowed), prescription medications known to influence vitamin D or calcium metabolism or gastric acid, excessive body weight change during the past 6 months, food allergies, unusual eating habits, or medically prescribed diets.
* Also excluded are prisoners and individuals who are cognitively impaired.

Primary outcomes:
measure: Calcium absorption and kinetics
timeFrame: Baseline, day 5 and week 6
Secondary outcomes:
measure: Serum Parathyroid hormone
timeFrame: baseline and weekly
measure: Markers of bone turnover
timeFrame: baseline and weekly
Other outcomes:
Locations:
city: New Haven
country: United States
facility: Yale New Haven Hospital Research Unit
state: Connecticut
Study officials:
affiliation: Yale University
name: Karl L Insogna, MD
role: PRINCIPAL_INVESTIGATOR
References: