Why Antacids Are a Poor Source of Calcium

Why Antacids Are a Poor Source of Calcium

By Andrea Bartels CNP NNCP RNT
Registered Nutritional Therapist

26 Apr 2023

Why Antacids Are a Poor Source of Calcium

With all the prescription drugs and natural health products that people take throughout their day, it’s easy to understand why a product that serves more than 1 need is attractive.

Consider your common over-the-counter calcium-based antacid. It’s used as a remedy for heartburn, but also touted by doctors and manufacturers as a good source of calcium. Sure, it’s a high source of calcium…but is it an effective one?

An antacid consists of a highly alkaline mineral compound, such as calcium carbonate. (Some antacids contain other minerals compounds, but I’ll stay focused on calcium here today.)

Antacids neutralize acids and inactivate protein-digesting enzymes secreted by the stomach. In using an antacid, the irritation that causes the uncomfortable burning pain of heartburn subsides.

Let’s consider that the initial step to the digestion of proteins requires the secretion of hydrochloric acid and acid-dependent enzymes. The problem is, taking an antacid on top of food is like using a fire-extinguisher.  What happens? The fire goes out.  By alkalizing the stomach contents, the antacid makes the job of completing digestion a tough one.  

Without acid, protein and fat-containing food just sits in the stomach. If food doesn’t get completely digested, it can cause gas, pain and IBS-like symptoms.  It also means we won’t break down food proteins into individual amino acids so we can make new ones.  Vitamins like B12 and minerals like iron and zinc will also be harder to extract from food. This limits their absorption and can potentially lead to health problems down the road with daily, long-term use.

Since calcium carbonate is classified as a non-absorbable antacid, you can expect to absorb only a maximum of 15-30 percent of calcium from antacid formulations.  The rest of it will be excreted via the stool. But that’s not all. Long-term, acid-rebound is possible, where the stomach increases its acid output, leading to a vicious cycle of antacid or prescription PPI use to manage the problem.

Up to 20 percent of Canadians experience GERD-- acid reflux-- on a regular basis. While many are managing their condition with prescription medications, there are thousands more who self-medicate with over-the-counter calcium-based antacids like TUMS, Rolaids, Maalox. If you’re one of them, don’t depend on these for calcium. Save them for heartburn.

Consider adding a low-dose, more complete calcium complex for bone support: one that can be taken with meals, without interfering with digestion and absorption of nutrients.


Pure Lab’s Calcium Hydroxyapatite is an organically bound calcium complex with the built-in benefits of minerals and proteins that are naturally occurring in the bone matrix: bone growth factors, proteins, calcium, phosphorus and trace minerals.

Calcium Hydroxyapatite has greater bioavailability than calcium citrate and calcium carbonate, with more of each dose absorbed into circulation. 


Pure Lab’s Calcium Hydroxyapatite contains only high-grade, certified BSE-free Australian bovine bone meal as its source material. 

Each capsule contains 250 milligrams of pure elemental calcium. With this, your daily dose can probably be achieved in just 1 or two capsules per meal. Just be sure to consider your dietary calcium intake.   And remember, calcium hydroxyapatite can be taken with meals because it won’t interfere with digestion and absorption of nutrients.



Cleveland Clinic. “Calcium carbonate chewable tablets”. Accessed online March 6, 2023.

Farrell CP, Morgan M, Rudolph DS, et al. Proton Pump Inhibitors Interfere With Zinc Absorption and Zinc Body Stores. Gastroenterology Res. 2011;4(6):243-251.

Fedorak RN, Veldhuyzen van Zanten S, Bridges R. Canadian Digestive Health Foundation Public Impact Series: gastroesophageal reflux disease in Canada: incidence, prevalence, and direct and indirect economic impact. Can J Gastroenterol. 2010;24(7):431-434.

Garg V, Narang P, Taneja R. Antacids revisited: review on contemporary facts and relevance for self-management. J Int Med Res. 2022 Mar;50(3):3000605221086457.

Government of Canada. “Prescription medication use among Canadian adults, 2016 to 2019.” Accessed online on March 6, 2023.

Vinnakota RD, Brett AS. Iron Deficiency Anemia Associated With Acid-Modifying Medications: Two Cases and Literature ReviewAm J Med Sci. 2019;357(2):160-163. 



According to the Canadian Health Measures Survey, from 2016 – 2019, Canadian adults between the ages of 18 and 79 used at least one prescription drug in the month prior to the survey. In fact, 36 percent were using 2 or more drugs, and 24% were using 3 or more.


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