I do not recommend calcium from coral. The chemistry of coral it is not that much different from oyster shell, which is a lot cheaper. Both coral and oyster shells contain minerals and trace minerals extracted from the water. In addition, both coral and oyster shell are composed primarily of calcium carbonate, which is one of the least absorbed forms of calcium available. Its popularity among manufacturers is only due to calcium carbonate being the cheapest form of supplemental calcium available.
Coral is a colony of living animals, called polyps. As fish respirate they release carbon dioxide into the water, which reacts with calcium to form calcium carbonate. The polyps extract the calcium carbonate from the water to cement themselves to a hard surface. New polyps then cement themselves to the old dead polyps and the cycle continues causing the coral to grow. In the process other minerals are extracted from the water. The primary component of coral though still remains calcium carbonate.
The big problem with calcium carbonate is that it is very alkaline and neutralizes acids. With the big push to alkalize this may sound good at first. Parts of the body need to be acid though and excess alkalinity (alkalosis) is a dangerous condition.
The biggest concern here is the stomach, which definitely needs to be acidic. The stomach needs to be acidic actually for several reasons. For instance in order to digest proteins the body uses an enzyme called pepsin. Pepsin cannot work without sufficient stomach acid being present. When stomach acid is in short supply partially digested proteins can be absorbed triggering off allergic responses. Certain vitamins such as vitamin B6, B12 and folate cannot be absorbed from the gut either unless there is sufficient stomach acid. Stomach acid levels naturally decline though with age, which is why deficiencies of these vitamins are common in the elderly. Without these vitamins a process known as methylation is reduced leading to increased risk of heart disease, allergies, low immunity, decreased energy, etc. Another problem is that many minerals cannot be absorbed unless there is sufficient stomach acid or food acids present or unless they are pre-acidified. By neutralizing stomach acid, carbonates actually interfere with the absorption of minerals such as calcium and the even more importantly silica.
Silica is the most important nutrient for bone health. It is also essential for healthy hair, nails, teeth, tendons, ligaments, arteries, etc. Silica deficiencies are also responsible for wrinkle formation since silica is essential for elastin formation, which helps keep the skin from sagging leading to wrinkles.
Another very important purpose of stomach acid is to control the growth of microbes such as bacteria and Candida fungi in the stomach since most are killed or controlled by acidity. Therefore, as stomach acid levels decline the risk of infection increases. For example, the most common cause of heartburn is a lack of stomach acid leading to increased fermentation in the stomach. This is in part due to increased time the food remains in the stomach, but also from microbial overgrowth in the stomach as acid levels decrease. Fermentation leads to gas formation that puts pressure on the stomach’s lower esophageal sphincter (LES) muscle. The resulting pressure tires out the LES muscle at the top of the stomach and it gives way allowing the gas to escape up the esophagus. When this happens, traces of acid go with the gas causing the heartburn. Unfortunately the medical community is still stuck on the long outdated idea that excessive stomach acid causes heartburn and they do not bother to read their own medical texts. Excessive stomach acid, a condition known as hyperchlorrhydria, is considered extremely rare. Yet antacids and acid blockers, which cover up the symptoms while making the underlying problem worse are the second largest selling drug class. One of these compounds commonly used to neutralize stomach acid is calcium carbonate, such as Tums. As with Tums, coral again is primarily calcium carbonate. Stomach acid is the first thing the carbonate in the coral is going to come into contact with. This neutralizes the stomach acid and the carbonate gets used up in the process leaving no carbonate to alkalize the blood unless taken in excessive amounts. Because stomach acid is so important, this is a real bad idea! The best way to get around this problem is to get your minerals from food or herbs. Minerals in plants are naturally chelated, which means they are bound to proteins. Being bound to proteins the body will accept these sources like foods and the proteins help chaperone the minerals into the body where they are separated and can do their job without neutralizing the stomach acid.
There are actually different chemical compositions in the corals taken from above the water and below the water. The below water coral has more nutrients. This is in part due to what else is in it. The below water coral is actually coral sand dredged from the bottom. Therefore, it not only is the broken down coral being sucked up but also any little plants and animals in the sand. The above water coral has been weathered and leached of many of its minerals.
In short, there are better choices for calcium than coral. For instance, if you want a great source of calcium and trace minerals then you could use Atlantic kelp, which not only contains these minerals but also vitamins, which are not found in coral. Seaweeds contain algins, which bind with heavy metals such as those found in the coral and the seaweeds themselves. By binding with the heavy metals algins pull these heavy metals from the body. Coral and colloidal minerals from shale deposits being sold as “plant derived” cannot do this.