A FREQUENTLY ASKED QUESTION in the vitamin aisles of health-food stores is, "What kind of calcium should I take?" Given the growing problem of osteoporosis, it's not surprising that most of the questioners are women.
Although women often take more calcium, men should make sure they also get sufficient amounts because they lose bone calcium at about the same rate as women. Blood lipid profiles and levels of LDL cholesterol also improve in men taking calcium supplements. Special attention should also be given to supplements for adolescents. Peak skeletal mass, developed during adolescence, is the best insurance against later development of osteoporosis.
Your daily diet impacts absorption of bone-building nutrients: for instance, every ounce of meat requires 24 mg of calcium to digest. In addition to meat, carbonated beverages are high in phosphorus, a mineral that interferes with bone formation. People who drink a lot of soda will have parathyroid levels at the high side of normal, which can slow the rate at which new bone is formed. Too much alcohol, caffeine, and salt can also increase the risk for bone loss.
And don¹t forget that calcium supplementation is only half the story. You need magnesium, as well, and in some incidences, vitamin D and other bone-building minerals.
Best Known Mineral Calcium is the most prevalent mineral in the body, totaling about 1200 grams in an adult. Although it represents only about 0.1 percent of total body weight, calcium plays an active role within every cell and all bodily fluids. About 99 percent of body calcium stores are found in bones and teeth in a complex known as hydroxyapatite, a crystalline substance composed of calcium, phosphorus, magnesium, and trace minerals including boron, copper, and zinc.
Like other minerals, calcium is always bound to another molecule called a ligand. Minerals are reactive elements with positive charges that bind to anything negatively charged. Ligands, being negatively charged, provide an electrically stable molecule when they are attached to minerals.
We think of bones as hard solid structures, and while they support the body, the skeleton represents a depository from which other tissues can draw needed minerals. So-called "soft tissues" (blood, lymph, and organs) all contain calcium‹much of it in free or ionized form. While soft tissue calcium makes up only one percent of the body¹s total, it provides the necessary positive charge to activate hundreds of important enzymatic reactions. These include cellular membrane transport, neuromuscular activation, hormonal activity and blood clotting
Bone is a dynamic material, constantly exchanging its minerals
with the blood. When bones pick up more calcium than they
release, bone is formed. When the soft tissues need calcium, the
opposite happens and calcium gets 
resorbed in the body. Throughout life, a balance
between bone formation and resorption must be maintained. The
best insurance for maintaining healthy calcium balance is to take
calcium supplements.
Other Minerals
Magnesium is the second most abundant intracellular mineral, after potassium. This critical mineral activates over 300 enzymes, the most important being those that produce energy. Magnesium also helps activate amino acids in the brain and central nervous system, assists hormone and protein synthesis and breakdown of DNA (the body¹s reproductive material). A probable contributor to both insulin resistance and impaired insulin secretion, magnesium deficiency is implicated in diabetes and obesity.
Deficiency of magnesium was once considered rare. However, recent findings suggest that many individuals have marginal magnesium levels. Sometimes called "nature¹s calcium channel blocker," magnesium balances calcium in muscle contraction and relaxation. If levels of magnesium are low, muscle cramping, nerve tension, coronary and cerebral blood vessel spasms can occur. Since magnesium and potassium balance one another within the cell, magnesium and potassium are often supplemented together.
Total body magnesium content is about 25 grams and half of this is stored in bone. Sometimes called "alkaline earth" elements, calcium and magnesium belong to the same chemical family. While they can compete with one another for uptake and absorption into tissues, these minerals also help one another work more effectively. The competitive/co-operative relationship of calcium and magnesium makes it imperative that they are both taken as supplements‹and most formulas supply both. It¹s a good idea to make sure your daily multiple provides trace minerals in addition to your calcium and magnesium supplement. The amounts needed are small in comparison to calcium and magnesium, so it¹s not difficult to fit daily required amount into a multiple formula.
Which Supplement Forms?
The most common form of calcium (and the least expensive) is calcium carbonate, an inorganic source mined from deposits throughout the world.
Tori Hudson, ND, professor of gynecology at the National College of Naturopathic Medicine in Portland, Oregon, advises choosing supplements with calcium chelates or refined calcium carbonate for absorption. Avoid supplements using bone meal, dolomite, and unrefined calcium carbonate, which contain lead. Or choose calcium citrate malate (CCM), originally developed to fortify orange juice and now available as a dietary supplement. CCM contains a ligand complex of carbonate, citrate, and malate in specific ratios, (Shils,152) shown in some studies to be more stable and better absorbed than calcium carbonate alone.
Calcium hydroxyapatite is another supplement form. Since it provides calcium, phosphorus, magnesium and trace minerals, many people choose this form because it contains all the minerals found in bone. However, studies at Creighton University in Omaha found hydroxyapatite was even less well absorbed than calcium carbonate, possibly due to the particular hydroxyapatite tested.
The best forms of magnesium to take are amino acid chelated or citrate. Magnesium oxide, an earth mined inorganic form, may be mixed with chelated or citrate forms because the yield of elemental magnesium is the greatest in the oxide form.However, magnesium oxide by itself can cause loose stools in some people. That's why combinations are best.
Most calcium and magnesium supplements contain twice the amount of calcium. However, dietary calcium is much more plentiful and based on recent findings, experts recommend equal amounts of both. More companies are offering this ratio, but you may have to buy separate bottles to obtain the forms mentioned above. Regardless of the form of minerals you choose, all are best taken with meals.
Since there is competition between calcium and magnesium, some healthcare providers recommend taking them at different times of the day, but for most of us, this isn¹t terribly practical and if you're taking amino acid chelated forms, it's not necessary. If you choose separate supplements, take calcium in the morning and magnesium in the evening, since magnesium is an excellent relaxant.
Anyone with hypertension, diabetes, or hormone imbalances can benefit from taking 50 percent more magnesium than calcium‹for up to three months. You will find you have more energy and less tension. Magnesium has been a favorite supplement for treating pre-menstrual syndrome among naturopathic physicians and be useful if you suffer from this condition.
And Vitamins?
Vitamin D is a key determinant in the maintenance of calcium and phosphorus levels within blood serum. Photosynthesized in the skin from ultra-violet B, this fat-soluble vitamin D is transformed into a steroid hormone in the kidneys. If you live in the northern tier of states where sun exposure is limited during winter months, consider adding vitamin D to your supplement program, as very little is available from foods other than fish liver oil.
The Food and Nutrition Board recommends 200 IU of vitamin D daily for infants through age 50. Up to 70, the recommendation is 400 IU, while those over 71 should take 600 IU. While young people may get enough vitamin D through fortified dairy products and grain beverages, most adults, especially past middle age, can benefit from supplementing with vitamin D. "Vitamin K is going to be the Œnew¹ bone-building vitamin, according to George Kessler, DO, clinical instructor in medicine at the Albert Einstein College of Medicine at Cornell University. This vitamin draws calcium to the bones and helps keep it there, making it useful in both bone formation and in slowing bone loss. Manufactured by healthy bacteria in the intestinal tract, vitamin K is lost when you take antibiotics, but this beneficial flora can be restored by taking probiotics such as acidophilus. In addition, research has found that taking more than 100 mcg of vitamin K daily was useful in preventing hip fractures among older women NOT taking hormone replacement therapy.§