Using Ca-41 Methodology to Assess the Impact of Different Vitamin D Supplementation Levels on Postmenopausal Bone Health

Using Ca-41 Methodology to Assess the Impact of Different Vitamin D Supplementation Levels on Postmenopausal Bone Health

The purpose of this study is to determine whether increasing levels of serum 25(OH)Vitamin D as achieved by oral supplementation higher than the current recommendations are associated with a less negative bone calcium balance in post-menopausal Swiss women.

In a substudy - not related to the vitamin D intervention - spot and 24 h urine samples are compared with regard to the assessment of iodine status in Swiss post-menopausal women.

In an short subsequent study using five of the subjects who participated in the original trial, the effect of a 40 d-exercise program (rebounding on a trampoline) on Ca-41 excretion will be observed.

Inclusion Criteria:

• apparently healthy women, at least 5 years post-menopausal
• BMI 18-30
• no HRT
• no regular intake of Ca or vit D supplements
• wiling and able to give written informed consent and to understand, participate and comply with study requirements
• non-smokers
• no long travels (>3 wk) planned within study period

Exclusion Criteria:

• diseases that predispose to osteoporosis
• history of fragility fractures
• currently on a weight reduction program
• excessive physical activity
• diseases influencing calcium metabolism (thyroid, parathyroid, adrenal disorders etc.)
• regular intake of medication affecting calcium metabolism
• osteoporosis (T-score below -2.5)
• history of psychological illness likely to interfere with the subject's ability to understand the requirements of the study
• participation in concurrent studies