Olympian, I think you may have misunderstood what I was trying to say, or I may not have been clear. First of all, as far as the space question goes, the reason the astronauts' bones wasn't absorbing calcium was that they weren't putting stress on the bones (no gravity) and thus the bones began to lose density, while at the same time not pulling calcium out of the blood because they weren't under any stress and had no need to repair. To some extent it's a moot point because we're talking about planet earth here. It is true that your body can absorb only a certain amount of calcium at a time--according to most studies anywhere from 300-500 mg every meal, and the rest will be excreted.
The question of calcium supplements came up here in reference to someone who has shin splints or stress fractures. In this case their body is going to have a greater demand for calcium due to the stress placed on the bone. If you ever get a bone scan, what they do is inject you with a mildly radioactive isotope of calcium in order to see where it goes, because if you have a stress fracture or other point of weakness, it is going to concentrate there. In other words, putting excessive stress on your skeleton (ie the bones in your lower leg) is going to increase your demand for calcium. I agree with Olympian 100% in that the average person has little need for calcium supplements. However, someone who is putting a lot of stress on their lower legs by running, kicking the muay thai bag, whatever, is going to benefit by upping their calcium intake, whether by eating more dairy products or taking supplements. That's all I meant--sorry if there was any confusion.
By the way, I have gotten stress fractures in my lower legs before, and the doctor had me supplementing my normal diet with 500 mg of calcium pills at every meal. And it worked.
Moto
The question of calcium supplements came up here in reference to someone who has shin splints or stress fractures. In this case their body is going to have a greater demand for calcium due to the stress placed on the bone. If you ever get a bone scan, what they do is inject you with a mildly radioactive isotope of calcium in order to see where it goes, because if you have a stress fracture or other point of weakness, it is going to concentrate there. In other words, putting excessive stress on your skeleton (ie the bones in your lower leg) is going to increase your demand for calcium. I agree with Olympian 100% in that the average person has little need for calcium supplements. However, someone who is putting a lot of stress on their lower legs by running, kicking the muay thai bag, whatever, is going to benefit by upping their calcium intake, whether by eating more dairy products or taking supplements. That's all I meant--sorry if there was any confusion.
By the way, I have gotten stress fractures in my lower legs before, and the doctor had me supplementing my normal diet with 500 mg of calcium pills at every meal. And it worked.
Moto