99% of Calcium is found in bone, 1% serves an intracellular messengers.
Most of that 99% of calcium in bone is found in bone with Phosphorous. Calcium in cells bind to proteins eliciting direct action of the proteins- like troponin-C in muscle for muscle movement), along with phosphorous, Calcium also helps activate other proteins like enzymes for blood clotting.
Calcium requires two mechanisms for absorption, one of these requires Vitamin D. Other vitamins that improve absorption include Vitamin E, Vitamin C, Phosphorous, Potassium and Magnesium.
Many other compounds or lifestyle factors help increase the excretion of Calcium. Excretion of Calcium is normal, however, if you supplement too much calcium at a time OR if these factors below are involved- the levels of excretion are not healthy because the calcium is not getting absorbed into your bones. You begin to lose bone after age 30, minimal amounts initially. This can lead to osteoporosis, which can be incredibly painful and cause fractures leading to eventual death ( immobilization, severity). These other factors for osteoporosis include:
- high sodium intake ( even normal intake at 2300mg/day causes you to excrete an additional 40mg of calcium/day)
-amenhoria and/or eating disorders ( because these both cause estrogen levels to drop severely, we want estrogen because it has a positive effect on bone density)
-post-menopausal women ( for same reasons above: estrogen levels drop in menopause, causing a decrease in bone density, decrease in calcium absorption)
- low physical activity ( weight bearing pulls muscles from bone, ultimately strengthening the bone and surrounding muscles).
-low calcium, vitamin D intake
-Steroids such as Prednisone * I am actually asking my prof. more about this, so I will update what I find *
-decreased sun exposure ( because the absorption of calcium requires vitamin D, if you decrease your sun exposure the chemical in your skin that converts uv rays to vitamin D will not convert)
- Higher intakes of Protein. I found this interesting because we went over two research studies that showed various results when supplementing protein and calcium and vitamin D in postmenopausal women.
In elderly women that were not getting enough calcium to start, the study found that adding in higher doses of protein actually increased secretion of Calcium ( decreasing absorption and thus bone density).
However, if the calcium intake was already sufficient, the added protein actually helped increase bone calcium absorption and decrease its secretion.
Fortunately for us, many natural diets include plenty of other vitamins and compounds that counteract the loss of calcium when consuming high protein diets.
This still makes me want to take calcium supplements BIG TIME! I used to take tums all the time, but now I eat lots of yogurt and calcium containing foods. If you do supplement calcium, do not consume more than 500 mg at a sitting because your body can only absorb that much at one time. The rest will be literally, ( excreted in your urine) and flushed down the toliet !