We all know what calcium is. It's that hard, whitish mineral substance that makes up the bulk of our teeth and bones. Some of us may also remember that calcium, in it's pure form, is a chemical element closely related to sodium and potassium, though not quite as active.

From a physiological standpoint, the role that sodium and potassium play in our lives may appear to be more subtle because we can't see what they do, but calcium has it's more subtle aspects, too.

Calcium is needed to help bind cells into organs, to transmit nerve impulses that control our muscles, and to release the chemicals that pass along signals between nerves.

Calcium aids in the production of hormones and enzymes and in controlling their activity, these include things such as regulating digestion, energy release, fat metabolism, and even saliva production. Calcium is also needed for cells to grow and for blood to clot.

And calcium supplements have been shown to reduce the risk of colon cancer in men, the symptoms of PMS in women, and the blood pressure of teens.

When we think of sources of calcium, most of us will immediately think of milk, but milk isn't really a very good source, even if we ignore homogenization and how that changes it, and the cattle-fed antibiotics and hormones that milk contains.

Fortunately, calcium is everywhere, though how much a given food source contains can very widely. Calves start their lives drinking milk but soon turn to eating grass -- vegetation -- the source of most of that bony mass on which they stand. Of course, they have to eat grass and hay and corn in huge quantities to get that way.

Calcium, Kids, Soft Drinks & pH

That today's children are drinking too many soft drinks is an issue of some concern for a variety of reasons. We'll look at those related to calcium, here.

Studies have shown that teen-aged girls who consume cola beverages are three times as likely to suffer bone fractures as those who don't, and that the more athletic among them are five times as likely to suffer bone fractures as teen girls who don't drink cola.

If you look at the label of Coke or Pepsi, you'll see phosphoric acid listed among the ingredients. Dr. Pepper contains phosphoric acid, too. Ginger Ale and many others list citric acid. Mountain Dew lists lactic acid. And of course, all list carbonated water which is carbon dioxide dissolved in water or carbonic acid.

pH is a way of determining the acidity or alkalinity of a solution by measuring the concentration of hydrogen ions it contains. If it has a low pH it is acidic. If it has a high pH it is alkaline. The pH scale ranges from 1-14 with 7 being neutral. As far as body chemistry is concerned, we need to maintain a slightly alkaline pH of 7.4 to stay healthy.

Eating enough fruits and vegetables is one way we help keep our system alkaline. Fruits and vegetables will, for example, help buffer acid meat proteins.

Minerals can also help neutralize acids. To buffer the acidic effects of anything we consume, minerals such as sodium, potassium, magnesium, and calcium are pulled from our system.

Now here's where this gets interesting.

To prevent damage to the urinary tract, anything with a pH lower than about 5 can't be excreted by the kidneys.

A 12 ounce can of cola with a pH of 2.8 to 3.2 would require some 100 liters of urine to bring it up to a pH of 5. That's more than 26 gallons of urine!

Since that isn't going to happen, what the body does is go the mineral route, first with easily accessible sodium potassium and carbonate, and later with magnesium and calcium. To bring the pH up to 5, it uses the mineral equivalent of 4 Tums tablets, drawn from the body, mostly from the bones.

Coke machines in schools may supply districts with needed funds, but there are many health issues at stake not the least of which is bone fractures now and osteoporosis later on, for teen-aged girls who drink cola.

The Truth About Coral Calcium

You've probably heard of coral calcium. Maybe you've even seen it sold through TV infomercials.

Unfortunately, most of its notoriety is based on highly exaggerated claims.

No, coral calcium is not a miraculous cure-all for some 200 diseases. And saying that it can extend life to 120 years is a transparently false conclusion based on a longevity study of Okinawans, the residents of the Ryukyu Islands, an island chain south of Japan from which virtually all coral calcium that's now being sold originates.

But promotional hype aside, coral calcium can be an important nutritional supplement for some very good reasons.

Coral calcium is very absorbable form of calcium.

Coral calcium contains magnesium. Magnesium aids in the absorption of calcium but magnesium is a mineral most of us get too little of.

Coral calcium contains 72 other minerals. Some of these are very important trace minerals that are generally absent from our food supply.

Coral calcium can alkalize your body and help keep your pH level where it should be for good health.