To Your Health

Q. I've seen ads that say coral calcium is easily absorbed, comes with some naturally occurring trace minerals, and helps maintain the right acid-alkaline balance in the body. Is coral calcium really better than other calcium sources?

A. Television infomercials and scores of Web sites promote coral calcium as a dietary supplement. There is no argument that calcium is an essential mineral with abundant health benefits. It is especially important for bone health and may play a role in the prevention of colon cancer. It is one of several "macrominerals" which govern the acid-alkaline balance in the body.

The calcium supplied by coral is advertised as being in "ionic form and highly bioavailable." However, according to Takuo Fujita, M.D., of Osaka, Japan, the calcium from coral is calcium carbonate and may act no differently than calcium from other, less expensive, sources. Dr. Fujita, recognized as an expert on calcium, is the founder of Japan's Calcium Research Institute, past president of Japan's Osteoporosis Foundation, and author of over 400 scientific papers on calcium.

There is no evidence presented in the advertisements to support the claim that coral calcium is in ionic form and therefore more bioavailable (useful for your body). There is only one Japanese study with 12 subjects suggesting that the calcium of coral origin is somewhat better absorbed than calcium of calcium-carbonate origin. In numerous other scientific studies, including studies on humans, coral calcium is no more available to the body than other forms of calcium. Abundant research shows that calcium carbonate is only about half as bioavailable as calcium bound to an organic molecule such as citrate.

Promoters claim that coral calcium from Okinawa contains 12% magnesium. Mineral analysis of coral shows only about 2% magnesium, so the daily dose of coral contains roughly 10 mg of magnesium. Most coral-calcium sources are fortified to bring the calcium-to-magnesium ratio up to the recommended 2 to 1. Unless trace minerals are added, coral provides less than 1 mg of any trace mineral (iron, copper, zinc, manganese, etc.) in the recommended amount for 500 mg of calcium.

Unfortunately toxic minerals are also found in coral. The recommended daily dose of coral that provides 500 mg of calcium also has 17 micrograms of lead. The Centers for Disease Control and Prevention argue that the daily amount of lead should be set at 25 mcg per day, so using coral for your calcium supplement would furnish half your daily allowance of lead. Similarly, if you are otherwise careful to avoid aluminum in your diet, coral-calcium supplements would double your aluminum intake. Unless natural calcium sources, such as coral, bone meal, and dolomite, are carefully processed, lead and other toxic minerals will come along with the calcium. In contrast, the calcium bound to organic molecules supplies virtually no toxic minerals.

Cost is one of the factors which people use to decide which nutritional supplement to buy. Coral calcium costs 60 cents per day or more, considerably higher than the best absorbed form of calcium (calcium citrate-malate) at 40 cents per day. The cost of calcium-carbonate tablets can be even less, 5 cents per day.

Coral calcium is a legitimate calcium source, but other forms have demonstrated better absorption at a more reasonable price.