GLOSSARY

Calcium Reference Table

US/Canadian adult mineral references, generally age 19-50; adult values are male / female. Magnesium values shown are age 19-30.

Calcium is essential for bone structure and cellular signaling; food calcium and free blood calcium are different measurements.

Most body calcium is in bones and teeth; a smaller pool supports signaling, contraction, secretion and coagulation. Bone strength also depends on energy, protein, vitamin D, hormones and mechanical loading. For an athlete at risk of bone stress injury, the whole nutrition and training context matters more than assuming one calcium tablet provides complete protection against injury.

Dairy, fortified plant drinks, calcium-set tofu and fish eaten with bones can supply calcium, but amounts and uptake differ. Check fortification and shaking instructions; plant drinks are not all enriched. Athletes avoiding dairy need an actual replacement assessed by consumed portions. A white beverage or adequate protein content does not guarantee calcium adequacy within the daily diet.

Calcium uptake uses regulated vitamin-D-dependent active transport and passive pathways. Serving amount, compound and meal context matter; fractional absorption need not remain constant as intake rises. High oxalate can limit availability from some vegetables, so spinach is not simply equivalent to a low-oxalate source. Supplements are evaluated by elemental amount, tolerance, timing and interacting medicines together.