The extent of a focal tendon abnormality was intrasubstance in none (0%) of 16 patients with full-thickness tears, one (20%) of five patients with bursal surface partial-thickness tears, two (20%) of 10 patients with articular surface partial-thickness tears, and two (15%) of 13 patients with tendons without tear.
1 Adequate Intake (AI), where no RDA has been established, but the amount established is somewhat less firmly believed to be adequate for everyone in the demographic group.  Tolerable upper intake levels (UL), to caution against excessive intake of nutrients (like vitamin A) that can be harmful in large amounts.
'When the supplement enters the blood, the body takes phosphate out of the bones to stick it to the calcium. The bones end up with less phosphate and no added calcium, so the calcium supplement is actually making the bones weaker.'. NO - they are not a waste of time and money. The main argument for using supplements is that we don't get enough nutrients from food - recommended daily allowances (RDAs) are just measurements of the minimum needed to prevent a physiological deficiency, rather than to maintain optimal health.