Calcium balance during human growth: evidence for threshold behavior

Area of Science:

• Human Nutrition
• Calcium Metabolism
• Pediatric and Adult Physiology

Background:

• Calcium is essential for bone health and numerous physiological functions throughout life.
• Understanding the relationship between calcium intake and balance is crucial for establishing optimal dietary recommendations.
• Existing data on calcium balance across diverse age groups requires synthesis to identify critical intake thresholds.

Purpose of the Study:

• To analyze the relationship between calcium intake and calcium balance across a wide age spectrum (birth to 30 years).
• To determine threshold intakes where calcium balance plateaus, irrespective of further intake increases.
• To compare these threshold intakes with established US recommended dietary allowances (RDAs).

Main Methods:

• Pooled data from 519 individuals across 34 published reports.
• Analysis stratified by age groups from infancy to young adulthood.
• Utilized a two-component, split, linear-regression model to estimate threshold intakes and balances.

Main Results:

• Calcium balance showed a strong positive correlation with intake at lower levels across all age groups.
• At higher intakes, calcium balance values flattened, indicating a plateau effect.
• Estimated threshold intakes, where balance ceased to increase with intake, were consistently higher than US RDAs for all age groups studied.

Conclusions:

• Current US recommended dietary allowances for calcium may be insufficient to achieve optimal calcium balance in individuals from infancy through young adulthood.
• Higher calcium intakes are required to reach a plateau in calcium retention than currently recommended.
• This suggests a need for re-evaluation of calcium intake guidelines, particularly for growing and young adult populations.