Calcium is not normally low in the bloodstream because there is a large reservoir of calcium in the bones. As long as the parathyroid glands are working normally, calcium levels are maintained in the blood. There are a few causes of low blood calcium that are not related to parathyroid hormone. The kidneys play a large role in blood calcium regulation, so kidney failure can cause calcium deficiency in the blood. You may recall that vitamin D is needed for calcium absorption. If vitamin D levels are abnormally low, then blood calcium may also be low. In cases of severe alcoholism, low magnesium levels can cause bone loss. The cells in bones that dissolve calcium out of bones, osteoclasts, become unresponsive to parathyroid hormone without enough magnesium.
Calcium Depletion from Excess Sodium
Excess dietary sodium can impact calcium levels in the body. Americans eat an average of five grams of excess sodium each day. This is the average amount above the upper intake levels. This extra sodium flushes an extra 86 mg of calcium out of the body through the kidneys each day. The most likely mechanism for this urinary loss is the competition between calcium and sodium for reabsorption in the tubules of the kidney.
If this extra 86 mg of calcium is absorbed from food sources in the intestines, then about 287 mg of extra dietary calcium is needed to account for this loss. Why is so much dietary calcium needed to replace smaller losses of urinary calcium? This is because calcium absorption from the intestines is not very efficient. Only about 30 percent of dietary calcium is absorbed from the intestines in adults (pregnant women and growing children are able to absorb about 50 percent of the calcium in food).
In some cases, the extra calcium lost in urine caused by excess sodium intake is not available from the food in the intestines. When dietary calcium is not available, this 86 mg of calcium must be removed from the bones. It is estimated that as much as one percent of the bones of adult women can be lost each year for every gram of excess sodium consumed daily. With sufficient dietary calcium, this bone loss can be prevented.
Calcium Depletion from Excess Protein
Americans regularly consume more protein than they need. On the average, women take in 24 extra grams per day and men take in an average of 44 extra grams per day of protein. This is the amount of protein consumed in excess of the RDA values of 46 grams for women and 56 grams for men. It is not uncommon for Americans to consume 100 grams of excess protein in a day.
As the intake of protein rises above the need for protein, the amount of calcium lost in urine also rises. It has been estimated that 1.75 mg of calcium is lost for each extra gram of protein consumed. Using this estimate, based upon 24 grams of excess protein, 42 mg of calcium may be lost each day because of excess protein consumption by the average American woman. With a 30 percent rate of absorption, this results in an extra dietary need of 140 mg of calcium.
For the average American man with 44 grams of excess protein, the amount of extra dietary calcium needed works out to be 257 mg. If 100 grams of excess protein are eaten, the amount of dietary calcium needed to offset the protein is 583 mg. On days of heavy protein consumption, bones may need to give up calcium unless extra calcium is consumed.
Extra calcium needed because of excess protein intake averages 140 mg for women and 257 mg for men.
The consumption of excess protein is thought to increase the amount of acids that must be neutralized by blood buffers. Protein eaten in excess of our needs is burned for energy. Calcium can be lost when it is used to neutralize the acids in blood that result from burning protein. Most of the phosphate in urine in America
comes from excessive protein intakes. The phosphate forms a complex with calcium and the calcium is lost in the urine. Small amounts of calcium may also be lost as a result of the phosphoric acid in some soft drinks and the diuretic action of coffee.
Calcium Depletion from Excess Sodium
Excess dietary sodium can impact calcium levels in the body. Americans eat an average of five grams of excess sodium each day. This is the average amount above the upper intake levels. This extra sodium flushes an extra 86 mg of calcium out of the body through the kidneys each day. The most likely mechanism for this urinary loss is the competition between calcium and sodium for reabsorption in the tubules of the kidney.
If this extra 86 mg of calcium is absorbed from food sources in the intestines, then about 287 mg of extra dietary calcium is needed to account for this loss. Why is so much dietary calcium needed to replace smaller losses of urinary calcium? This is because calcium absorption from the intestines is not very efficient. Only about 30 percent of dietary calcium is absorbed from the intestines in adults (pregnant women and growing children are able to absorb about 50 percent of the calcium in food).
In some cases, the extra calcium lost in urine caused by excess sodium intake is not available from the food in the intestines. When dietary calcium is not available, this 86 mg of calcium must be removed from the bones. It is estimated that as much as one percent of the bones of adult women can be lost each year for every gram of excess sodium consumed daily. With sufficient dietary calcium, this bone loss can be prevented.
Calcium Depletion from Excess Protein
Americans regularly consume more protein than they need. On the average, women take in 24 extra grams per day and men take in an average of 44 extra grams per day of protein. This is the amount of protein consumed in excess of the RDA values of 46 grams for women and 56 grams for men. It is not uncommon for Americans to consume 100 grams of excess protein in a day.
As the intake of protein rises above the need for protein, the amount of calcium lost in urine also rises. It has been estimated that 1.75 mg of calcium is lost for each extra gram of protein consumed. Using this estimate, based upon 24 grams of excess protein, 42 mg of calcium may be lost each day because of excess protein consumption by the average American woman. With a 30 percent rate of absorption, this results in an extra dietary need of 140 mg of calcium.
For the average American man with 44 grams of excess protein, the amount of extra dietary calcium needed works out to be 257 mg. If 100 grams of excess protein are eaten, the amount of dietary calcium needed to offset the protein is 583 mg. On days of heavy protein consumption, bones may need to give up calcium unless extra calcium is consumed.
Extra calcium needed because of excess protein intake averages 140 mg for women and 257 mg for men.
The consumption of excess protein is thought to increase the amount of acids that must be neutralized by blood buffers. Protein eaten in excess of our needs is burned for energy. Calcium can be lost when it is used to neutralize the acids in blood that result from burning protein. Most of the phosphate in urine in America
comes from excessive protein intakes. The phosphate forms a complex with calcium and the calcium is lost in the urine. Small amounts of calcium may also be lost as a result of the phosphoric acid in some soft drinks and the diuretic action of coffee.
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