Aside from its well-known role in bone health, calcium is important for cardiovascular health, nerve transmission, muscle movement and hormone regulation, all of which are carried out by the calcium present in your blood. When your blood calcium runs low, your body will try to absorb more calcium from the diet, reduce calcium excretion through the kidneys, and mobilize more calcium from your bones to normalize. Chronic dietary calcium inadequacy slowly drains the calcium reservoir in your bones and leads to osteoporosis.
Who Needs a Calcium Supplement?
The populations at risk of calcium inadequacy may require calcium supplementation. These individuals either do not take in enough dietary calcium, have difficulty obtaining, retaining or mobilizing calcium, or have increased demand for calcium that is difficult to meet with diet alone. For example, vegetarians who exclude dairy products and people who have lactose intolerance may not get enough calcium through diet. Growing children, adolescents, pregnant and lactating women need more calcium to support the growing bones, and dietary calcium may not be sufficient. Calcium supplementation is indicated for these at-risk groups.
Choosing a Calcium Supplement
Calcium supplements come in two major forms: calcium carbonate and calcium citrate. If you don't have stomach problems, choosing calcium carbonate will give you more calcium for the weight. As calcium carbonate requires stomach acid for absorption, take calcium carbonate with food or a glass of orange juice, recommended by the University of Maryland Medical Center. If you have a condition that reduces stomach acid production, such as gastric atrophy, calcium citrate is a better choice. It is less dependent on the stomach acid and you can take it on empty stomach so it won't interfere with the absorption of iron and zinc from food.
Calcium Supplement Side Effects
Calcium supplements can cause constipation, gas and bloating. These effects are more common with calcium carbonate supplement, according to the Office of Dietary Supplements. Take the supplement with six to eight cups of water a day to prevent constipation. Calcium supplementation is associated with increased risk of prostate cancer and kidney stones. The effects appear to be unique to the supplements because dietary calcium protect against kidney stones, as reviewed by the Office of Dietary Supplement. Based on these considerations, the Institute of Medicine sets the upper tolerable level of calcium at 2,500 mg daily for adults aged 19 to 50 and 2,000 mg for the elderly over the age of 50.
Other Considerations
Your body can only absorb up to 500 mg calcium at one sitting. Spread out your calcium intake throughout the day in smaller doses can maximize the absorption. If you are taking calcium citrate, you should avoid aluminum-containing antacids as calcium citrate increases the absorption of aluminum, which can be toxic, especially when you have underlying kidney disease that impairs the removal of this mineral from the body. Choose a calcium supplement that also contains vitamin D. Without vitamin D, calcium is not well-absorbed and may even be harmful. Calcium-only supplement increases the risk of heart attack and fractures, according to Harvard University.
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