If calcium is soluble, it dissolves easily in water or stomach acid. (In fact, it is not uncommon for calcium supplements to be close to 100 percent soluble.) Calcium dissolves in the stomach and is absorbed through the lining of the small intestine into the bloodstream. Once in the bloodstream, calcium builds bone, regulates the expansion and contraction of the blood vessels, and performs other important functions.
Here are key factors that can affect how well your body is able to absorb the calcium you take in.
- A diet high in phytic acid — Found in the bran coating of whole grains, phytic acid binds calcium and other minerals, making them insoluble and not absorbable in the intestines. Your calcium then passes out of the body without being absorbed. If you typically consume a lot of whole-grain bread and cereal, you may want to try calcium-fortified products.
- High levels of sodium — Excessive salt can interfere with calcium absorption. Read more about salt and the health of your bones.
- Insufficient vitamin D — Vitamin D is critical to regulating calcium absorption.
- Coffee (and tea) consumption — The caffeine in coffee, tea, as well as most sodas acts as a mild diuretic, so that valuable calcium is excreted before the body can make use of it. Consuming these drinks in small quantities is relatively harmless, but excessive use can lead to reduced absorption.
- Smoking — Studies of smokers show reduced bone mass. The reason is not well understood, but it appears that smoking interferes with the absorption of calcium in the intestines. PLEASE STOP SMOKING.
- Celiac Disease — This health condition is an inherited autoimmune disease characterized by gluten intolerance. It often goes undiagnosed in both children and adults. Celiac disease changes the lining of the intestine and impacts absorption of fat-soluble vitamins and minerals, such as vitamin D and calcium. If you have celiac disease, it is a significant risk factor for osteoporosis.
Other factors, such as an inactive lifestyle and a diet that features a large amount of meat, may also affect your ability to absorb calcium. American Bone Health suggests that you discuss these factors with your healthcare provider and evaluate your own diet and lifestyle for areas where you can make improvements.
Posted: 9/28/2016; Revised: 03/04/20.
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