Calcium

Nutrient Reference Values for Calcium

Importance of Calcium

  • Role in Body: Essential for skeletal development and maintenance, neuromuscular function, and cardiac function.

  • Storage: Primarily stored in teeth and bones, providing structure and strength.

Health Implications of Calcium Deficiency

  • Osteoporosis: Associated with low calcium intake.

    • Common in Western cultures, especially in older Australians and New Zealanders.

    • Particularly affects postmenopausal women.

    • Increases the risk of bone fractures.

  • Bone Density Changes:

    • Bone mass increases significantly during childhood and adolescence.

    • After age 50 in men and menopause in women, bone density may decline.

Factors Affecting Calcium Balance

  • Calcium Intake vs. Absorption:

    • Balance between intake and absorption versus losses (skin, kidney, bowel).

    • Recent revisions have included sweat losses in intake recommendations.

  • Menopausal Changes:

    • Decline in intestinal absorption and increased urinary excretion lead to faster calcium loss.

  • Exercise: Plays a supportive role in maintaining bone health.

Calcium Supplementation Studies

  • Studies show varying results:

    • Up to 70% reduction in hip fractures with calcium supplements.

    • Other studies show no significant effect on reducing fractures or improving bone density.

  • Cautious Recommendations:

    • High calcium intake may slow bone loss in postmenopausal women but may not significantly reduce fracture risk.

Dietary Sources of Calcium

  • Rich Sources:

    • Predominantly found in milk and dairy products.

    • Other sources include bony fish, legumes, nuts, fortified foods.

  • Bioavailability Concerns:

    • Absorption varies; foods high in oxalates (e.g., spinach) have lower bioavailability.

    • Soy products can vary in calcium absorbability when compared to dairy.

Specific Intake Recommendations by Age Group

  • Infants:

    • 0-6 months: AI of 210 mg/day.

    • 7-12 months: AI of 270 mg/day (considering breastfed and complementary foods).

  • Children (1-8 years):

    • EAR for calcium set at 200 mg/day.

  • Adolescents (12-18 years):

    • Significant increase in calcium needs due to skeletal growth. RDI set at 1300 mg/day.

  • Adults:

    • EAR calculated at 840 mg/day covering basal needs and losses.

    • RDI: 1000 mg/day for men and premenopausal women; 1300 mg/day for postmenopausal women.

  • Pregnancy:

    • No additional need for calcium intake during pregnancy; maternal adaptation suffices for fetal needs.

  • Lactation:

    • Approximately 210 mg/day secreted in breast milk; no need for increased dietary calcium.

Upper Intake Levels and Safety

  • Tolerable Upper Intake Level (UL):

    • Set conservatively at 2500 mg/day for all population groups.

    • Risk of kidney stones at higher intakes must be considered.

    • Toxic effects mainly seen at extremely high doses, particularly from calcium supplements.

Conclusion

  • Adequate calcium intake is crucial for maintaining bone health across life stages.

  • Recommendations vary based on physiological needs and changes at different stages in life.