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Good Sources of Calcium

Good-Sources-Calcium | Review ArticleGood sources of calcium seemingly abound, from sardines to calcium-infused juices. However, the calcium bioavailability of those foods can vary.  Ideally, you should define good sources of calcium as foods that are rich in a calcium form that is also highly absorbable.

Below are some examples of foods rich in calcium, listed on the National Institutes of Health (NIH) calcium fact sheet:        

Food Calcium (mg)
Yogurt, plain, 8 ounces  415
Sardines, canned with bones, 3 ounces 324
Cheddar cheese, 1.5 ounces  306
Milk, nonfat, 8 ounces 302
Mozzarella, part skim, 1.5 ounces 275
Orange juice, calcium-fortified, 6 ounces 200
Salmon, pink, canned, with bone, 3 ounces 181
Cottage cheese, 1% milk fat, 1 cup 138
Spinach, ½ cup 120
Kale, 1 cup  90

Is Calcium Really Being Absorbed?
Foods rich in calcium are NOT always  good sources of calcium for absorption.  Take raw good-sources-calcium | Articlespinach; it’s obviously rich in calcium, plus you benefit from all the other vitamins and minerals found in leafy greens. However, Robert Heaney, MD found in a 1990 article published in Calcified Tissue International that only about 1% of calcium from spinach was absorbed using a double isotope test model. That compared with a 33% calcium absorption rate from milk.  The reason -- the calcium in spinach is calcium oxalate, which is nearly impossible for the body to breakdown.   Note: some people believe that cooking spinach may remove or change the oxalate form.

Calcium supplements, by definition, are almost always good sources of calcium. The most commonly used calcium in supplements is calcium carbonate. It’s inexpensive and contains more elemental calcium per gram than other forms. Carbonate is found in antacids, many leading supermarket supplements, breakfast cereals, and ocean-sourced calciums (such as algae or coral supplements).

However, like spinach, calcium carbonate is not absorbable under certain conditions. One is achlorhydria, or the inability to produce stomach acid.  Research suggests that achlorhydria is found in older adults, particularly those 60+.  If a calcium carbonate capsule or tablet (non-chewable) is consumed without food, it will be malabsorbed in people with achlorhydria. This highlights the fallacy of only focusing on good sources of calcium. Similar malabsorption has been found in people who take calcium carbonate pills between meals while on certain acid blockers.

More Absorbable Calcium Supplements
Which calcium forms are highly absorbable?  Two studies suggest that calcium carbonate and calcium citrate are absorbed about the same when taken with foods, based on a certain absorption model. Other researchers –using different techniques – found citrate more absorbable.  Using multiple absorption models, Takuo Fujita, MD found that the AAACa calcium in AdvaCAL was highly bioavailable compared to calcium carbonate, calcium lactate and calcium citrate malate. He also found that AdvaCAL increased bone density in studies whereas calcium carbonate did not.  

Because of the debate on the accuracy and reliability of different absorption models, good-sources-calcium | Articleit’s hard to make a definitive list of highly absorbable calcium forms.  However, this much can be said. A calcium, like AdvaCAL, that significantly increases bone density should be classified among the good sources of calcium .