Coral calcium

Coral calcium is a salt of calcium derived from fossilized coral reefs.

Chemistry
Coral calcium is composed primarily of calcium carbonate (CaCO3), with small amounts of magnesium and other trace minerals. Calcium carbonate from coral is similar to calcium carbonate from other sources, with varying amounts of trace minerals. Much attention has been given to calcium carbonate's ability to change the pH (or alkalinity) of water-based solutions to which it is added. With respect to pH and alkalinity, the calcium component is less important than the carbonate component, which is chemically similar to the bicarbonate in baking soda. Coral calcium is a source of calcium, which is an essential mineral for human life. Coral has a chemical structure that is very similar to the composition of human bone and is sometimes used as material in bone grafts.

Production
Coral grains are mined from fossilized coral beds on the coastline, and pumped from coral beds in shallow waters. Grains are then ground into a fine powder, and heat treated up to 1000 °F and/or ozonated depending on the grade. The final product is either bagged as powder, or mixed with silicon dioxide (an anti-caking agent), rice flour, and magnesium stearate which acts as a lubricant, then encapsulated and bottled for retail sale.

Health claims
Coral calcium has been promoted as an alternative treatment or cure for a number of health conditions, including cancer. There is no medical evidence to support these claims, and coral calcium has been identified by the United States Food and Drug Administration as a "Fake Cancer 'Cure' Consumers Should Avoid". The Federal Trade Commission prosecuted several individuals for making unsupported health claims about coral calcium, and the National Center for Complementary and Alternative Medicine has issued a consumer advisory regarding false and misleading marketing claims associated with coral calcium supplements.

Health and environmental concerns
Living coral reefs are endangered and cannot be harvested without significant damage to the ecosystem, and because of this, coral calcium is harvested by grinding up above-ground limestone deposits that were once part of a coral reef. Calcium from coral sources needs to be refined to remove pollutants of the source environment. It is marketed as a dietary supplement, but its benefits over other calcium supplements are unproven and biologically unlikely, and several marketers have been found guilty of fraud and were ordered to pay $20.4 million and to refrain from making unsubstantiated claims in the future. Additionally, coral near Okinawa has absorbed relatively high amounts of lead and mercury, leading to concern that these unregulated supplements may be contaminated. Further, coral takes millennia to grow, leading to environmental concerns.