Calcium absorption from supplements: carbonates v/s citrates

There  is much speculation over the use of calcium supplements. Some believe that calcium supplements cause more harm as they can lead to calcification of the arteries increasing risk of heart attack.  The concern is valid but if you take calcium from the right source, in the right quantity and right time then you can avoid such side-effects.

We present to you a brief overview of the absorption of calcium from its different forms.

Calcium carbonate :  The carbonate containing calcium supplements are heavy on the stomach and often cause constipation and bloating. Besides, they are insoluble in water and hence absorption is low (22% of CaCO3 is absorbed normally, dependent on gastric pH). Being carbonates (alkaline in nature), they alter the pH of the stomach thereby reducing the absorption of other nutrients such as iron which require acidic pH. However, these are the most common form of calcium supplements and also the cheapest.

Calcium citrate: It is the relatively more expensive form but does not require acidic conditions for its absorption.This can be particularly beneficial for those who have low stomach acids (achlorhydria) such as elderly, individuals suffering from reflux disease , etc. This form of calcium is absorbed  2.5 times faster than calcium carbonate, independent of gastric pH.  If calcium carbonates are causing excessive gastric problems, then it is better to try citrate forms.

Calcium citrate malate:   This is a calcium salt of citric acid and malic acid which releases calcium ions and citrate complex upon dissoultion. This form of calcium has excellent solubility which enhances calcium absorption (45% of Ca is absorbed from CCM). Calcium ions are absorbed directly into intestinal cells, and the citrate complex enters the body through paracellular absorption. Unlike other form of calcium supplements , Calcium citrate malate is recognized as a calcium source that does not increase the risk of kidney stones.

Choosing the right form of calcium can ensure that you are actually absorbing the calcium to maintain  healthy bones. In our next blog, read about the amount/quantity of calcium required though supplements.


Author: drpoojachhawcharia

Dr Pooja Chhawcharia is the Senior Nutritionist at eKincare with over 7 years of experience in Nutrition education, diet counseling and research. She is a Registered Dietician with the Indian Dietetic Association and Certified Diabetes Educator recognized by the International Diabetes federation . She is also interested in ancillary sciences such as Yoga and Naturopathy.

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