Functions

Calcium is the most abundant mineral in our bodies. Ninety nine percent of the calcium in our bodies is found in bones and teeth,bound to phospate and magnesium, the other one percent is in the serum, bound to albumin. The calcium in the bloodstream is involved in the formation of new bones and teeth, it controls muscle contractions, helps transmit nerve impulses, plays a role in blood clotting, and also is involved in the secretion of hormones. It is a very tightly regulated bloodstream element.

Thirty to forty percent of dietary calcium is absorbed. It is bound to oxalates and phytates in plant foods.

Uses

Osteoporosis, muscle cramping

Deficiency

Deficiencies of calcium are relatively common; they cause a decrease in bone density which may lead to osteoporosis, particularly in thin Caucasian or Asian women. A malabsorption of calcium leads to rickets, a bony deformity.

Deficiencies may be caused by sedentary lifestyle, impaired absorption, a low calcium diet, increased blood pressure. Alcohol and smoking increases the loss of calcium.

Antagonists

High levels of fat reduce absorption as do phytates, a class of compounds found in dietary fiber and oxalates which are found in leafy greens. Low stomach acid reduces absorption.

Co-factors

Blood levels are tightly regulated by calcitonin, a hormone, parathyroid hormone and vitamin D. Absorption is enhanced by low blood levels and by moderate exercise.

Drug Interactions

Some diuretics, corticosteroids and antidepressants can lead to calcium deficiency. Calcium supplements may decrease the effectiveness of tetracycline antibiotics; the anticonvulsant, phenytoin; and aspirin; and should not be taken at the same time as any of these drugs.

Dose

RDA: Adult: 1000 mg, 14-18 y old 1300 mg, over 50 y 1200 mg. Pregnant: 1000 mg Lactating: 1000 mg

Calcium supplements take various forms. Most common is calcium carbonate, which is poorly absorbed. Calcium glucoranate or calcium citrate are better options for supplementation. Calcium and magnesium must be supplemented together!

Toxicity

Excess calcium may cause constipation or kidney stones.

Sources

Dairy products; Salmon, sardines, oysters, herring; Seaweed; Dark green leafy vegetables; Broccoli; Dried beans and peas; Nuts and seeds; Sprouts; Soybeans, tofu, tempeh; Brewer's yeast; Blackstrap molasses; Whole grains; Herbs such as borage, lamb's quarters, wild lettuce, amaranth, nettles, campion, burdock, and yellow dock leaves.