Calcium, the major constituent of the structural framework of bones, is the body’s most prevalent mineral. Approximately three pounds of a 160-pound man’s weight are calcium. For both men and women, 98% of the body’s calcium is found in the bones, 1% in the teeth, and the remaining 1% in soft body tissues, where it performs a variety of essential functions.
In addition to supporting the growth and continued strength of bones and teeth, calcium helps maintain cell membranes and the “cement” that holds cells together. It is essential to proper blood clotting, and it assists in regulating the transport of ions in and out of cells, thus making muscular contractions and relaxation possible.
The bones act as a calcium deposit for the rest of the body. Although they are commonly thought of as fixed, solid objects, bones continually lose and regain calcium. A network of hormones keeps the calcium level in blood and other bodily fluids at a constant level, depositing temporary excesses in the bones and removing calcium from the bones if it is needed elsewhere.
The richest food sources of calcium are milk and dairy products, including yogurt and hard cheeses. Canned sardines and salmon, caviar, almonds and Brazilian nuts, molasses, shrimp, soybeans, tofu, and green, leafy vegetables (particularly collard and dandelion greens and spinach) also are good sources, but oxalic acid in spinach renders much of the vegetable’s calcium insoluble and nonabsorbable.
A persistent calcium shortage leads to distorted bone growth in children and a softening and deterioration of bones in adults. Osteoporosis, a weakening of the bones, affects one in four women after menopause. An inadequate calcium supply occurs when too little is consumed, too much is lost, or not enough is absorbed. At the other extreme, an excess of calcium in the body has been shown to depress nerve function, cause drowsiness and extreme lethargy, and decrease iron levels.
A vitamin D deficiency interferes with the absorption of calcium through the intestinal tract. Calcium absorption is also impaired by excessive dietary fat and continued use of corticosteroids, the synthetic equivalent of hormones made in the adrenal gland. Patients with irritable bowel syndrome (IBS), for example, have been shown to be at risk of developing calcium deficiency due to malabsorption, cortisoid use, and vitamin D deficiency. As a result, IBS patients are at risk for metabolic bone diseases.
Lack of dietary calcium in adults can result in a condition known as osteomalacia, or softening of the bone. In contrast, those suffering from osteoporosis have a deficiency of both calcium and other minerals, as well as a decrease in the nonmineral framework (organic matrix) of bone. Taking calcium supplements has proved effective in reducing age-related bone loss. Currently, calcium citrate appears to be the best form of calcium supplement, both in terms of better absorption and decreased risk of developing kidney stones.
Calcium deficiencies also may be indirectly related to hypertension. Several studies show that people with hypertension consume a smaller amount of daily calcium than non-hypertensive people, and may benefit from calcium supplementation. Clinical studies have demonstrated that calcium supplementation may also lower blood pressure. According to Dr. Leon Chaitow in The Mind/Body Purification Program, people living in areas with a soft-water supply (water with increased lead levels) are at risk for hypertension, and this may be partly due to the fact that soft water is normally low in calcium and magnesium. Coffee, alcohol, and smoking reduce calcium levels in the body and are associated with an increased risk of developing osteoporosis.
Along with other nutrients, calcium has been used with moderate success to reduce the risk of angina and heart disease. It also is routinely prescribed by naturopaths for mild allergies. In addition, calcium has been used to reduce cholesterol. In one study, reported in the Encyclopedia of Natural Medicine, a daily administration of two grams of calcium carbonate (800 milligrams of elemental calcium) resulted in a 25% decrease in serum cholesterol in men with high cholesterol levels, over a period of one year.
Iron is an essential ingredient in all cells, particularly the oxygen-carrying cells of theblood and muscles, which use two-thirds of the iron requirement. Without iron, hemoglobin (the oxygen transport pigment of red blood cells) and myoglobin (the hemoglobin of muscle cells) cannot be formed, nor can certain vital enzymes.
Iron found in animal foods such as beef, liver, fish, and poultry is more readily absorbed than that found in milk, eggs, cheese, or vegetables such as spinach. Eating foods containing iron along with foods rich in vitamin C, such as citrus fruits, tomatoes, or green peppers, can enhance iron absorption. Several foods and beverages contain substances that inhibit iron absorption, including tea, coffee, wheat bran, and egg yolks. Overuse of antacids and calcium supplements also decreases iron absorption. These items should be restricted in the diets of individuals with iron deficiencies.
Iron deficiency, or anemia, can produce such symptoms as fatigue, listlessness, irritability, pallor, and shortness of breath, which reflect a lack of oxygen being delivered to tissues and a build-up of carbon dioxide. The problem most commonly occurs in infants, young children, adolescents, and women of child-bearing age, some of whom may need to take iron supplements.
Iron supplements are routinely given to pregnant and nursing women. However, they should not be taken without a physician’s recommendation based on one or more blood tests. Since iron is stored in the body and lost only through bleeding, it is possible to accumulate an excess of iron that can damage the liver, pancreas, and heart.
A 1986 study by the U.S. Department of Agriculture (USDA) has found that women who have below-normal iron supplies may start feeling cold before they experience tiredness, the usual side effect of iron-deficiency anemia. The USDA study concluded that all women of child-bearing age (roughly ages 1950) have iron intakes of only 61% of the Recommended Daily Allowance. Additionally, E. Pollitt, in the April 1976 Journal of Pediatrics, noted that iron deficiency is the second most common nutritional problem for all Americans after obesity.