CALCIUM

Calcium is crucial to maintain life. Just about every cell in the body, including those in the heart, nerves and muscles, relies on calcium to function properly. Bones require calcium to maintain their strength. Calcium is found in three places in the body, the skeleton and teeth, cells and blood. Because calcium is so important, the body has a carefully regulated system to ensure that a good supply is always- and immediately-available. The body does it in three ways: it absorbs calcium directly from the food we eat, it takes calcium from our bones if there is not enough available. When this happens, the bones become less dense and more fragile. It slows down the amount of calcium that leaves the body in the urine by returning some to the blood stream where it remains available to organs and cells. The main goal of good calcium nutrition is to maintain an adequate supply so that our bodies do not have to dip into our only calcium reservoir- our bones.

The role of calcium in building stronger bones:

In childhood, calcium is necessary to grow a healthy skeleton to support a growing body. By age 20 in men and age 16 in women, bones typically stop growing in length and we are almost at our peak bone mass. The density of our bones at this point depends a lot upon our calcium intake as children and teenagers. The greater this peak bone mass, the less likely our bones are to become porous and fragile later in life.

Bone is living tissue, constantly renewing itself. Although bone is strong and relatively flexible, everyday wear and tear causes tiny structural defects, much like those that occur in the foundations of a building over time.

In our bodies, there are two groups of specialized cells that perform the work of a "maintenance crew."

Osteoclasts excavate any areas of crumbling or weakened bone and then osteoblasts fill in the crevices with material that calcifies to form new bone. This two-part process is called bone remodeling, and is completed every three to four months in a healthy young adult. As we age, the two groups of cells that form the maintenance crew become less efficient in working together - the osteoclasts remove old bone faster than the osteoblasts are able to rebuild it. In addition, calcium, like many nutrients, is absorbed less effectively as we age. In people who have relatively healthy bones, adequate calcium intake can help the remodeling process stay balanced. Studies of older adults show that adequate calcium intake can slow bone loss and lower the risk of fracture.

Important facts about calcium:

Calcium is so demanding that it refuses to work in the presence of some of the most common components of the traditional healthy diet. Certain kinds of fiber, for example, bind to the mineral and blocks its absorption. Excess protein also appears to interfere with calcium uptake and can actually increase calcium loss.

Calcium is finicky; your body can't absorb it in the presence of certain other substances--such as iron, another essential mineral.

Often the very foods that would seem to be good calcium sources also contain substances that keep you from absorbing the calcium they contain. Spinach, for example, like other leafy green vegetables, is high in calcium, but it also contains high levels of oxalic acid, a substance that interferes with calcium absorption. The result is that your body doesn't get much of the calcium in spinach at all.

Because most multivitamin supplements recommended for women contain iron, which inhibits calcium, you should take your multivitamin and your calcium supplement at separate times of the day.
Calcium is best absorbed if consumed in split doses throughout the day. Generally, our bodies can only absorb about 500 mg of elemental calcium at a time.
Aluminum-containing antacids, iron supplements and some prescription medications will interfere with absorption and retention of your calcium supplement and vice versa.
Consult with your doctor about the possibility of such an interaction.
Because calcium is so important, the body has a carefully regulated system to ensure that a good supply is always — and immediately — available when needed.
The body does this in three ways: It absorbs calcium directly from the food that you eat. This is the preferable way for the body to get calcium. It takes calcium from your bones if there is not enough available when it is needed. When this happens, the bones become thinner and more fragile. It slows down the amount of calcium that leaves the body in the urine by returning some to the blood stream where it remains available to organs and cells.

Special Considerations

Phosphorus is a mineral people get from eating protein rich foods such as meat and milk. Some soft drinks, such as colas, also contain phosphorus. While phosphorus is needed to form bones and teeth, medical studies have shown that too much phosphorus in the diet may upset the calcium balance in humans. A good guide is not to go over twice the RDA of protein, and to limit the intake of carbonated beverages

Fiber should be part of a healthy diet. There are certain types of fiber that can affect the amount of calcium the body absorbs. Rhubarb, spinach, chard, and beet greens contain oxalate, which may decrease the absorption of calcium. Phytic acid, found in wheat bran, combines with calcium and also decreases its absorption. Fiber, however, is very helpful to the digestive tract, so it is important to balance the level of calcium intake with the amount and type of fiber in the diet. A diet containing up to 35 grams of fiber per day should be adequate for healthy bowel movements, without adversely affecting calcium absorption.

Caffeine increases the loss of calcium through the kidneys and intestines. While a moderate amount of caffeine per day (300-400 mg) has only a small effect, more caffeine may cause a much greater loss of calcium. Therefore, avoid drinking more than three cups of regular coffee or other high caffeine beverages a day.

Excessive alcohol intake may lead to loss of calcium in the bone. Poor nutrition is often related to abuse of alcohol. It has also been shown that alcohol has a toxic effect on the formation of bone cells. Do not have more than one or two drinks per day. One drink would be 12 oz of beer, 5 oz of wine, or 1.5 oz of 80 proof distilled spirits.

Lifestyle can have an effect on the risk of developing osteoporosis. Cigarette smoking increases bone loss, and it may cause lower estrogen levels. Regular exercise, including moderate weight-bearing exercise, helps prevent bone loss and increases the total amount of bone in the body. This is especially important for the elderly who tend to become sedentary. Examples of weight-bearing exercises include walking, cross-country skiing, jogging, aerobic dancing, and weight-training. The use of estrogen replacement therapy is very helpful for women who are no longer producing estrogen. Estrogen replacement must be prescribed by a physician.

Food sources of calcium include milk and dairy products, which are the best sources of absorbable calcium. About 25% to 35% of the calcium in dairy products is absorbed in normal healthy people. Dark green leafy vegetables also contain moderate amounts of calcium, but their content of oxalate and fiber may cause less of the calcium to be absorbed. Whole grain flours contain more calcium than milled white flours; however, whole grain flours contain more fiber and phytic acid. Fish and tofu (processed with calcium) are also good sources of calcium. Foods such as orange juice, breakfast cereals, breads, milk, and yogurt are often fortified with calcium. Product labels should be checked for the amount of calcium the foods contain.

Calcium supplements may be necessary to get adequate calcium intake. A physician or registered dietitian should be consulted about the need for calcium supplements. Several different forms of calcium supplements are available. Calcium carbonate is generally recommended because it contains the highest percentage of absorbable calcium, 40%. Calcium citrate is 21% calcium; calcium lactate is 13%; and calcium gluconate is only 9% calcium. Bone meal and dolomite are not recommended because they may contain toxic substances such as lead, mercury and arsenic. Chelated calcium is expensive and has no advantage over other forms. Long-term ingestion of excessive amounts of calcium can lead to unhealthy side effects, but taking 1000 mg to 2000 mg of calcium a day should not produce any serious problems.

Is more calcium better?

If you consume more calcium than recommended, there is no proof that it will benefit your bones.
High calcium intakes consumed on a regular basis may be harmful. It is important to get your daily recommended daily calcium and not to consume more than 2500 milligrams of calcium per day. The adverse effects of excessive calcium intake may include high blood calcium levels, kidney stone formation and kidney complications.

taking too much calcium:

has been associated with a decreased iron absorption, with the possible side effect of anemia

will interfere with the absorption of zinc--important for both bone and immune system health

may interfere with the synthesis of vit K which is not only important for appropriate blood clotting, but also plays a key role in bone health

can cause kidney disorders in susceptible people, if you have a history of kidney stones, make sure your doctor knows this before you start a regimen of calcium supplements

will block the uptake of manganese and interfere with the absorption of magnesium, which is also important for bone health

Young People Get Osteoporosis Too

Is more calcium better?