The recommended daily allowance (RDA) is 700 to 800 mg (0.7 to 0.8 g) per day. Some people remain in balance on lower intakes. The WHO recommends only 400 to 500 mg per day for adults. Because of increased calcium excretion higher in high protein diets, a higher calcium intake is recommended. For pregnant and lactating women, 1200 mg daily is advised; and 1200 to 1500 mg for women over 50.

After age 40, the calcium requirement increases as the efficiency of intestinal calcium absorption progressively declines. Postmenopausal women and most elderly men must increase their intake 50% to adapt to changing needs and to avoid negative balance.

Calcium is found almost exclusively in three classes of foods - milk and milk products, green vegetables, and a some fish and shellfish. In terms of calcium per 100 kcalories, green vegetables seem to be an excellent source. However, there is an uncertainty as to its absorption from green vegetables.

Milk is an excellent source, because of its calcium absorbability. However, to obtain 1500 mg of calcium from milk, it will require an intake of more than 5 cups, providing about 90 calories per cup of nonfat milk - or 450 calories per day. Alas, to the calorie-counting dieter.

FOOD ITEMS

Calcium
per serving (mg)

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100 KCal (mg)

CORAL CALCIUM
There is a recent calcium supplement craze, feeding off osteoporosis fears. It is Coral Calcium, label-embellished with "mariine-grade, above-sea" and "superior to below-sea coral" with experts and proponents from both coral sea-levels flooding the cyberspace search engines.

Calcium is an essential mineral, and coral calcium (calcium carbonate) is one form of its many sources. To date, there has not been any studies proving superioriry of coral calcium to other forms of calcium supplements.

Two debunking website articles: "Coral Calcium debunked" and "Coral Calcium: The Joke's On You."

CALCIUM SUPPLEMENTS DIFFER IN BIOAVAILABILITY, SIMPLE ACID TEST SHOWS
Calcium supplements differ in bioavailability. The stomach absorbs some better than others. Dr. Michael Hollick, director of the Bone Healthcare Clinic at the Boston Medical Center, suggested a simple test to gauge the ability of the stomach for calcium supplement absorption. Mix the calcium preparation in white vinegar. In 20 minutes, if it hasn't dissolved in white vinegar, it's not likely to dissolve in your stomach either.

VEGANS DON'T NEED DAIRY FOR GOOD BONE HEALTHDespite the vegan's dairy-free diet, they are in surprisingly good bone health. A study by Heather Hinkley, Ph.d and colleagues of the British College of Osteopathic Medicine in London, was done on 20-40 year-old women, followed for a minimum of 5 years, evaluated with broadband ultrasound attenuation of the calcaneum for bone mineral density assessment. There was no age-related decline in ultrasound attenuation among vegans. There was no statistical diffrerence between vegans and omnivores. The researchers speculate that a vegan diet may actually benefit bone health. 60% of vegans took calcium supplements which mave have contributed to the increased bone density. Also, the lack of dietary animal protein may be beneficial to the acid-base balance, with resulting less movement of bone mineral and decreased calcium excretion with preservation of bone integrity.