The Confusion Over Calcium

In the past Calcium has been a mineral largely taken for granted in our diet, with the notion that drinking milk was sufficient. Now it is the supplement of choice, being prescribed by doctors and nutritionists, or people are self-prescribing by recommendations made through research and the media. Over the past decade Calcium has become a well-known mineral responsible for such vital functions as building and maintaining healthy bones and teeth, controlling the conduction of nerve impulses and muscle contraction, including the heart muscle. It also aids in blood clotting, controlling cholesterol levels and B12 absorption. Currently calcium is most well known for the role it plays in preventing osteoporosis.
Unfortunately, despite supplementation, osteoporosis remains prevalent. Illustrating that the human body needs to be able to absorb and utilize the calcium that is being ingested. Researchers have turned towards supplements to try to identify how to best facilitate this, looking at the source, co-factors and environment. There are many forms of calcium currently available, such as calcium carbonate, calcium citrate, calcium gluconate, oyster shell, scallop shell, eggshell, milk products and the latest, coral calcium.

Absorb more.
As calcium is ingested, the acid in the stomach begins to break down the molecule into its atomic components. In the case of calcium carbonate, the components are elemental calcium and carbonic acid, which further breaks down into carbon dioxide. Once calcium is in its ionic state it can pass through the intestinal tract, into the bloodstream, and into the bones. It is this rate of calcium bioavailability, that determines how much of the ingested calcium can be used by the body. So the faster a supplement can achieve an ionic state, the faster it becomes available for absorption. Studies have shown that as long as the body absorbs enough calcium, the rate of absorption is not indicative of the quality of the calcium.

If the type of calcium does not make a huge difference to the bioavailability of a calcium supplement- what does?
The absorption and uptake of calcium are partly a function of pH. Acidity favors absorption while alkalinity hinders absorption. With normal healthy gastric function (which is acidic by nature) almost all forms of calcium become soluble and bio-available.
The levels of calcium in various products vary from 9 percent in calcium gluconate to nearly 40 percent in calcium carbonate. These levels of calcium do not appear to affect the bioavailability and absorption of the calcium. As supplements pass through the body, studies have shown there is little difference in bioavailability between all major types of calcium. When taken with meals, calcium carbonate has been shown to be as or more absorbable as five other forms of calcium, including calcium acetate, calcium lactate, milk, calcium citrate and calcium gluconate.

It matters less what kind of calcium you take than when you take it. Calcium taken with a meal is absorbed better than calcium taken without food. This has to do with the phosphate content of the food as well as the nutrients found in the food such as magnesium, vitamin D, proteins and lactose.

Equal in absorption, but what about quality?
In today's world the source of the calcium is an important consideration. Similar forms of calcium may come from different sources. For example, calcium carbonate can come from a variety of fossilized deposit sources: limestone, precipitated limestone, oyster shell, scallop shell, eggshell, fish bones and coral. The age of the deposit is the only major difference between the sources. Recent deposits mainly made up of oyster shells, scallops and corals, are subjected to all elements in the surrounding water, and with the state of the rivers and oceans becoming more polluted, it may be wise to seek a calcium supplement that is sourced from a high quality mine, that is further inland and much less susceptible to environmental pollutants.
Years ago calcium carbonate from bone meal or oyster shells was used in some supplements- but was later found to contain high levels of lead. Since then lead content is strictly monitored in calcium carbonate supplements. When addressing quality it is important to keep in mind that new calcium supplements, such as coral calcium, are not regulated in this fashion.