Calcium absorption in postmenopausal Chinese women: a randomized crossover intervention study

Area of Science:

• Nutritional Science
• Bone Metabolism
• Gerontology

Background:

• Calcium intake and metabolism differ significantly between Western and Chinese postmenopausal women.
• Limited data exists on calcium metabolism within Chinese populations.

Purpose of the Study:

• To determine true fractional calcium absorption (TFCA), true calcium absorption (Va), urinary calcium excretion (Vu), and net calcium balance (Va-u) in response to varying dietary calcium intakes.
• To establish optimal calcium intake levels for maximizing calcium retention in Chinese postmenopausal women.

Main Methods:

• A randomized crossover trial involving 21 healthy postmenopausal Chinese women (aged 49-64 years).
• Subjects received 0, 500, and 1000 mg calcium/day for 5 weeks each, with 2-week washout periods.
• True fractional calcium absorption was measured using stable isotopes; total urinary calcium excretion and calcium intake were also determined.

Main Results:

• Mean calcium intake levels were 391, 880, and 1382 mg/day.
• TFCA decreased significantly with increased calcium intake (from 0.57 to 0.43).
• Urinary calcium, Va, and Va-u increased significantly with supplementation, approaching a plateau around 1300 mg/day intake.

Conclusions:

• Postmenopausal Chinese women possess a high capacity for calcium absorption.
• A mean daily calcium intake of approximately 1300 mg is suggested to maximize net calcium absorption (Va-u) in this population.