Why? Maybe the wrong amount of calcium? Pretty much the same amount of calcium was used in both the studies. Compliance? Well in the urinary calcium tests that they did on the women who were taking it, it looked like at least those patients were taking the calcium they should be. They did pill counts for most people, and it seemed like compliance was okay. Poor definitions in the meta-analysis? That's always a problem; meta-analyses can get you in trouble that way. Is a supplement the same as dietary calcium? That's a really interesting point because there's some studies in the cardiovascular literature illustrating that calcium given in dairy products may have different effects than if it's given in pills, so that's possible. On the other hand and I think this is the one that is probably true is that maybe it's good for some people, but it's good for people who have a very low calcium intake. We tried to look at that in the NIH study by doing urinary calcium tests but even the women who have low urine calcium got nothing when compared to what you find in South American countries. The people who have done these calcium studies, especially people in South America are really convinced that it's useful. They actually have data on some of the children of mothers who took calcium and it looks like their blood pressure might also be lower. They're currently in the process of putting together a fairly large trial of 9,000 women from areas in which calcium intake is known to be low.