Calcium intake is below the EAR for an estimated 40-50% of Americans, particularly older adults, postmenopausal women, and adolescent girls. Important nuance: serum calcium is tightly regulated by drawing from bones, so chronic dietary inadequacy primarily shows up as bone loss (osteoporosis, osteomalacia) rather than abnormal blood levels. Acute hypocalcemia (blood calcium <8.5 mg/dL) is usually caused by medical conditions, not diet.
Common symptoms
Most chronic calcium inadequacy is silent until a fracture occurs
Acute hypocalcemia: muscle cramps and spasms (especially hands, face)
Tingling around the mouth or in fingertips and toes
Trousseau and Chvostek signs (clinical hypocalcemia indicators)
Seizures (severe acute hypocalcemia)
Heart rhythm disturbances (severe cases)
At-risk groups
Postmenopausal women (estrogen loss accelerates bone resorption)
Older adults (decreased intake plus reduced absorption)
Adolescent girls (peak bone-building years; intake often falls short)
People with vitamin D deficiency (vitamin D required for calcium absorption)
People with lactose intolerance who don't substitute calcium-rich foods
Vegans not consuming fortified foods
People with hypoparathyroidism or kidney disease
People on long-term proton pump inhibitors or corticosteroids
People who've had bariatric surgery
When to see a doctorBone pain, muscle cramps, or a fracture from a minor fall warrants medical evaluation including bone density scan (DEXA) and possibly serum calcium, vitamin D, and PTH testing. For chronic prevention, focus first on dietary calcium plus adequate vitamin D and weight-bearing exercise. Excessive supplemental calcium (>1,500 mg/day) has been linked to kidney stones and possibly cardiovascular concerns — food sources are preferred.