Calcium supplements represent a valid help in case of reduced intake of the mineral with the diet or increased need. For this reason they are especially recommended for people who are allergic or intolerant to milk and dairy products, during pregnancy and breastfeeding, and for women in the postmenopausal period.
Not all calcium supplements are created equal. In fact, within them we do not find elemental calcium but its salts (calcium phosphate, calcium carbonate, calcium gluconate, etc.). We are in fact talking about a very reactive element, which is combined with other substances for technical and functional needs; depending on the compound with which it is associated, for example, the solubility in water, the bioavailability and the percentage on tot grams change. Even in nature, calcium is never present in the elemental state but is found in various compounds, generically called calcium salts.
We must therefore be aware that by ingesting one gram of a calcium salt, for example calcium carbonate, one does not take one gram of elemental calcium, but much less (in this specific case 0.4 grams, ie 400 mg). This very important consideration is often naively or "slyly" ignored even by the manufacturers of calcium supplements themselves. On the contrary, a serious product that respects the regulations in force, shows the quantity of elemental calcium on the label, converting it based on the raw material used. In this regard, the wording "calcium carbonate 2500 mg" is equivalent to "calcium (carbonate) 1000 mg" while if we find on the label the words "calcium carbonate 1000 mg" we are faced with a product with a 2.5 times elemental calcium content lower than the previous ones; the brackets, therefore, make the difference.
Below is a simple calculation module to find out the quantity of elemental calcium contained in x grams of a given raw material (to enter decimals use the point and not the comma, eg 5.5 and not 5.5).
Recommended Intake Levels of Calcium (mg / day) LARN, 1996
Football *
* Elementary calcium
Supplement
Elementary Ca
Calcium carbonate
40%
Calcium citrate
21%
Dibasic calcium phosphate
23%
Tribasic calcium phosphate
38%
Calcium lactate
13%
Calcium gluconate
9%
Calcium carbonate and calcium citrate are the most common preparations used in calcium supplements, since those gluconates and lactates contain a lower percentage of elemental calcium and are more expensive. However, some of these forms find space in the pharmaceutical field; calcium chloride is for example used intravenously as a cardiotonic and in the presence of severe hypocalcemia.
Calcium carbonate, in particular, contains the highest percentage of elemental calcium and its intake is recommended in conjunction with meals, because gastric juices increase its bioavailability by breaking up the tablet; it can also be taken on an empty stomach while sipping a citrus juice, for example to avoid that a meal rich in fiber (whole grains and vegetables) limits its absorption. In addition to being the most common preparation used in calcium-based supplements, it is frequently included in the composition of antacid drugs.
Calcium citrate, on the other hand, contains less elemental calcium but is more easily absorbed on an empty stomach (it is indicated in the presence of hypochlorhydria or hypoacidity). With the same elemental calcium, it has a cost up to two times higher than calcium carbonate on the finished product.
To increase the absorption of the mineral, calcium is sometimes associated with vitamin D (cholecalciferol), for the same reason the daily dose is often divided into two doses, generally at the main meals.
Finally, it is important not to exceed the recommended doses and ask your doctor or pharmacist for advice on any contraindications or interactions with medicines taken at the same time (for example, calcium supplements can alter the absorption of tetracyclines, decreasing their effect).
