contain 20-30 times as much phosphorus as calcium. Molasses is fairly high in calcium, while some fruits, such as citrus, figs, raisins, and dried apricots, have modest amounts.

When the diet is high in phosphorus, we can lose extra calcium through the urine, resulting in calcium being pulled out of the bones. Phosphorus is very plentiful in meat foods and is of particular concern in soda pops that have added phosphoric acid (phosphate). This phosphorus-calcium imbalance may lead to kidney stones and other calcification problems, as well as increased atherosclerotic plaque. This issue is fairly complex and is under investigation. It is currently felt that the best calcium-phosphorus ratio in the diet is about 1:1.

Sunlight increases the manufacture of vitamin D in the body, and is like having an extra calcium source because vitamin D improves absorption of any available dietary calcium. Calcium supplements could be taken in the first couple of hours after sunbathing to improve utilization.

Dolomite and bonemeal (ground cattle bones) are good sources of calcium and magnesium. In recent years, however, both of these natural sources have been found to be contaminated with lead and other heavy metal toxicants. It is probably wise not to take these supplements in large amounts or over prolonged periods of time unless they are tested for contamination. Calcium found in "hard" water may also be an important source for maintaining body levels.

Functions: Calcium has some very important life-supporting functions; the best known is the development and maintenance of bones and teeth. Our need for calcium is critical during the growth years of infancy and childhood, but it is also important lifelong to keep our bones healthy. Exercise, vitamin D, and many other nutrients, such as phosphorus and magnesium, are also needed to maintain our skeleton. Bones are primarily calcium phosphate and a protein matrix. Tooth enamel is the hardest substance in the body, made up of 99 percent minerals, primarily calcium.

Bones are not only our most basic physical support structure, they are the main reservoir for calcium. Most minerals are in a state of dynamic activity and function, and even the calcium in bones is being added to and removed depending on the calcium balance in the body. The bones provide calcium to the blood and other tissues when we are not getting sufficient amounts from our diet. Vitamin D, parathyroid hormone, and calcitonin are responsible for maintaining this balance.

Circulating calcium also performs many other vital functions. Ionized (Ca++) calcium is needed for muscle contraction, as in muscular activity and in regulating the heartbeat. Heart function is mediated by several minerals: calcium stimulates contraction, magnesium supports the relaxation phase, and sodium and potassium are also important in generating the electrical impulse. Exercise can improve the circulation of calcium as well as that of all the other nutrients and thereby help the tone and function of the muscles, heart, and nervous system.

With regard to the nervous system, calcium is important in nerve transmission. Calcium ions influence nerve and cell membranes and the release of neurotransmitters. Calcium activates some enzyme systems, such as choline acetylase, which helps generate acetylcholine, an important neurotransmitter. Norepinephrine and serotonin are also affected by calcium. Calcium is said to be calming to the nerves, as higher concentrations tend to decrease nerve irritability.

Calcium plays an important role in the cells as well; it is necessary in cell division. Calcium is needed to activate prothrombin, which helps convert fibrinogen to fibrin and is essential to blood coagulation.

Uses: Calcium is one of the minerals most commonly prescribed by medical doctors (potassium is the other main one) because calcium deficiency is common and causes bone weakness through loss of bone calcium in the disease called osteoporosis. Osteoporosis is more common in the elderly population and occurs four times as often in women as in men. It can also occur at younger ages with chronic dietary insufficiency of calcium or with early menopause. Good evidence shows that there is a relationship between decreased calcium intake and osteoporosis; lack of exercise also increases bone loss. Moderate daily exercise as well as supplementing calcium and vitamin D results in reduced to restore a positive calcium balance. The best way to combat osteoporosis is to prevent it with regular exercise, a calcium-rich diet not too high in phosphorus, calcium supplements, and for menopausal women considering estrogen therapy. Exercise can actually stimulate bone renewal by improving bone uptake of calcium and other minerals.

Osteoporosis (the term literally means "porous bones") is actually a loss of bone mass as the result of the loss of both minerals and protein; this differs slightly from osteomalacia, the bone problem seen in adults with vitamin D deficiency, which involves a softening of bones due to mineral loss alone. Rickets is the childhood equivalent of osteomalacia and is also caused by vitamin D deficiency. Extra calcium can help alleviate these problems somewhat, but the body needs supplemental vitamin D to get appreciable levels of calcium into the blood, tissues, and bones.

Calcium is the primary substance used in the prevention and treatment of osteoporosis, though estrogen used in menopausal hormone replacement therapy can reduce the likelihood of this disease in women. Since osteoporosis is found mainly in menopausal and postmenopausal woman, calcium is commonly seen as a treatment for problems of menopause. It does, in fact, reduce a number of the potential symptoms. Calcium not only helps the bones, especially when supplemented with magnesium and vitamin D, but may also reduce the headaches, irritability, insomnia, and depression sometimes associated with menopause. It is likely that a high percentage-as much as 70-90 percent-of bone fractures in people over 60 years of age are due to osteoporosis. These fractures are often more serious than an average fracture, because demineralized bones shatter when they break and take longer to heal. Actually, because osteoporotic fractures usually occur in the elderly and are so disabling, about one in six people dies within three months after sustaining them. Therefore, by helping to retard osteoporosis, calcium can prevent some fractures.

Osteoporosis is most common in elderly white women with a history of borderline calcium intake. Calcium is often drained from the bones during pregnancy and nursing and becomes hard to replace in later years, especially with reduced consumption of milk products and a lower calcium intake in general. Calcium supplementation can be helpful in reducing the leg cramps of pregnancy and the fatigue and depression after delivery. Children's leg cramps are usually reduced by giving them calcium and magnesium. Calcium supplements tend to stimulate retention of calcium and decrease urinary excretion.

Calcium is often helpful for menstrual problems, particularly menstrual cramps, irritability or apprehension, and muscle cramps that occur around menstruation. The recently recognized premenstrual syndrome is often helped in part with additional calcium, though magnesium supplementation may be even more important. In some cases, however, reducing calcium intake can be helpful. Generally, muscle cramps or leg and foot cramps can be helped by calcium and vitamin D. Also, some cases of hyperkinesis in children, when associated with calcium deficiency, may be helped by supplementation.

Other problems related to bone health affect the mouth, jawbone, and teeth. In some cases, calcium may be helpful for problems of loose teeth, gingivitis (gum inflammation), and periodontal disease. Usually 1,000 mg. of calcium supplemented in the diet along with a dietary intake of phosphorus ranging from 1,000-2,000 mg. is suggested.

Calcium is often used to reduce heart irregularity; along with magnesium, it helps regulate heart contraction and relaxation. Through increasing contractility, calcium can help in congestive heart failure. Additional calcium may protect us from the toxicity of cadmium, rubidium, or mercury exposure by competing for absorption. Proper calcium intake may reduce the incidence of colon and rectal cancers through forming insoluble soaps with some mild carcinogens produced in the body, including bile acids and free, ionized fatty acids. A good calcium-phosphorus ratio in the diet also reduces the risk of cancer in the large intestine.

Deficiency and toxicity: In general, a high calcium intake for brief periods does not cause any problems, as excesses are usually eliminated in the urine and intestines. With magnesium deficiency, though, high amounts of calcium or vitamin D can lead to calcification of the soft tissues or to kidney stone formation. It is possible that prolonged high amounts of calcium (higher than a 2:1 calcium-phosphorus ratio) and supplemental vitamin D can lead to abnormal calcification of long bones in children or to hypercalcemia (high blood calcium levels) and soft tissue calcification in adults, as well as a decrease in bone strength. Also, if the parathyroid glands are not functioning well, calcium can accumulate and cause problems.

Calcium itself is thought to be one of the concerns in atherosclerosis, forming part of the plaque laid down in the arteries. Guy Abraham, M.D., who is known for his work in premenstrual syndrome, expressed a real concern over routine calcium supplementation in our society as he feels it exacerbates the degenerative process in the blood vessels, kidneys, and other organs and tissues. It is possible that these problems of calcium excess are not specifically related to dietary calcium but rather to calcium's metabolism in relationship to the endocrine system. More research is clearly needed in this area. This potential toxicity concern makes me realize that it is important to be very aware of calcium metabolism and individual needs and to not just blindly supplement it as is so common recently.

Still, though, calcium deficiency is a more common concern in our culture than is excess calcium. This is especially true for the elderly, for alcoholics, for pregnant women, and for people with gastrointestinal disease. The "standard" American diet does not meet the normal calcium requirements; part of this problem is due to high phosphorus levels in the diet. Phosphorus is found in most foods, but soda pops, diet pops, meats, eggs, and processed foods such as lunch meats and cheese spreads contain especially high amounts. The ideal dietary phosphorus-calcium ratio is about 1:1. The ratio in the average American diet is often greater than 2:1 and sometimes even 4:1 or 5:1. At those levels, excess calcium is removed from bone and eliminated, blood levels are reduced, and there is bone demineralization. A diet high in phosphorus and low in calcium has been shown to cause bone loss and increase tissue calcification.

The skeletal system suffers most from calcium deficiency. Teeth minerals are more stable, though there is a possibility of poor dentition with insufficient calcium. Tooth loss, periodontal disease, and gingivitis can be problems, especially with a high phosphorus intake, particularly from soft drinks. All kinds of bone problems can occur with prolonged calcium deficiency, which causes a decrease in bone mass. Rickets in children, osteomalacia (decreased bone calcium) in adults, and osteoporosis (porous and fragile bones) can occur when calcium is withdrawn from bones faster than it is deposited. Fractures are more common with osteoporosis-almost eight million yearly in the United States are related to this prevalent nutritional deficiency disease. Although there must be loss in bone mass of almost 40 percent before it is visible by X-ray, the problem may be detected earlier through diet history or blood and nutritional tests. A program of regular exercise and calcium intake through diet and supplements, while limiting phosphorus intake, is a good way to prevent bone loss in the first place.