Is it true that after age of 70+ taking calcium supplement is no longer useful ?

Not true: Calcium with vitamin d requirement increases in the elderly. Less exposure to sunlight and low dietary intake often leads to low levels of vitamin d and less calcium available to maintain the strength of bones. This can progress to osteoporosis which is a major cause of hip joint and spinal fractures in the elderly. Hip fracture often is the terminal event for an elderly individual.