Which of the following best explains why the tolerable upper intake level (UL) for calcium is set lower for many older adults (≈2000 mg/day) than for younger adults (≈2500 mg/day)?

• A. Calcitonin secretion increases with age, so any more than 2000 mg/day will always cause severe hypocalcemia in older adults
• B. Age-related decreases in renal function and greater susceptibility to adverse effects (eg, hypercalcemia and kidney stones) make older adults more vulnerable to excess calcium intake
• C. Bone remodeling ceases in older adults, so additional calcium cannot be stored and instantaneously raises serum calcium above safe levels
• D. Older adults have a higher rate of intestinal calcium absorption that quickly produces toxicity at lower intakes

Answer: (B)