Calcium

Calcium is the body's most abundant mineral, concentrated in bones and teeth, which serve as a reservoir. It is also essential for muscle contraction, nerve transmission, blood clotting, and hormone signaling. When dietary calcium is inadequate, the body draws on bone, weakening it over time and raising osteoporosis and fracture risk.

Recommended intake (Institute of Medicine):

• Adults 19–50: 1,000 mg/day.
• Women 51+ and men 71+: 1,200 mg/day (men 51–70 remain at 1,000 mg).
• Tolerable upper limit: 2,500 mg/day for adults 19–50; 2,000 mg/day for 51+.

Calcium absorption depends on adequate vitamin D (see vitamin-d). Rich sources include dairy, fortified plant milks, canned fish with bones, tofu set with calcium, and leafy greens. At-risk groups include postmenopausal women, older adults, and people avoiding dairy without fortified replacements. Weight-bearing and resistance exercise complements calcium and vitamin D in building and preserving bone (see bone-tissue). Calcium is best obtained from food; supplements help fill genuine gaps but very high supplemental doses confer no extra benefit.

• Most abundant body mineral; bone reservoir plus muscle/nerve/clotting roles.
• RDA 1,000 mg/day (19–50); 1,200 mg/day women 51+ and men 71+.
• Upper limit 2,500 mg/day (19–50), 2,000 mg/day (51+).
• Absorption requires vitamin D.
• At-risk: postmenopausal women, older adults, dairy-avoiders.

• vitamin-d — required for calcium absorption.
• minerals-overview — calcium among the key minerals.
• prenatal-postpartum — elevated needs in pregnancy/lactation.
• bone-tissue — calcium's structural role.