Calcium is important for bone health. See how much calcium you need and how to get it.

By Mayo Clinic Staff

Calcium is important for optimal bone health throughout your life. Although diet is the best way to get calcium, calcium supplements may be an option if your diet falls short.

Before you consider calcium supplements, be sure you understand how much calcium you need, the pros and cons of calcium supplements, and which type of supplement to choose.

Your body needs calcium to build and maintain strong bones. Your heart, muscles and nerves also need calcium to function properly.

Some studies suggest that calcium, along with vitamin D, may have benefits beyond bone health: perhaps protecting against cancer, diabetes and high blood pressure. But evidence about such health benefits is not definitive.

If you don't get enough calcium, you could face health problems related to weak bones:

  • Children may not reach their full potential adult height.
  • Adults may have low bone mass, which is a risk factor for osteoporosis.

Many Americans don't get enough calcium in their diets. Children and adolescent girls are at particular risk, but so are adults age 50 and older.

How much calcium you need depends on your age and sex. Note that the upper limit in the chart represents the safe boundary — it's not how much you should aim to get. If you exceed the upper limit, you may increase your risk of health problems related to excessive calcium.

Calcium: Recommended Dietary Allowance (RDA) for adults
Men Daily RDA Daily upper limit
19-50 years 1,000 mg 2,500 mg
51-70 years 1,000 mg 2,000 mg
71 and older 1,200 mg 2,000 mg
Women Daily RDA Daily upper limit
19-50 years 1,000 mg 2,500 mg
51 and older 1,200 mg 2,000 mg

Your body doesn't produce calcium, so you must get it through other sources. Calcium can be found in a variety of foods, including:

  • Dairy products, such as cheese, milk and yogurt
  • Dark green leafy vegetables, such as broccoli and kale
  • Fish with edible soft bones, such as sardines and canned salmon
  • Calcium-fortified foods and beverages, such as soy products, cereal and fruit juices, and milk substitutes

To absorb calcium, your body also needs vitamin D. A few foods naturally contain small amounts of vitamin D, such as canned salmon with bones and egg yolks. You can also get vitamin D from fortified foods and sun exposure. The RDA for vitamin D is 600 international units (15 micrograms) a day for most adults.

Even if you eat a healthy, balanced diet, you may find it difficult to get enough calcium if you:

  • Follow a vegan diet
  • Have lactose intolerance and limit dairy products
  • Consume large amounts of protein or sodium, which can cause your body to excrete more calcium
  • Have osteoporosis
  • Are receiving long-term treatment with corticosteroids
  • Have certain bowel or digestive diseases that decrease your ability to absorb calcium, such as inflammatory bowel disease or celiac disease

In these situations, calcium supplements may help you meet your calcium requirements. Talk to your doctor or dietitian to determine if calcium supplements are right for you.

Calcium supplements aren't for everyone. For instance, if you have a health condition that causes excess calcium in your bloodstream (hypercalcemia), you should avoid calcium supplements.

It's not definitive, but there may be a link between calcium supplements and heart disease. The evidence is mixed and more research is needed before doctors know the effect calcium supplements may have on heart attack risk.

A similar controversy surrounds calcium and prostate cancer. Some studies have shown that high calcium intake from dairy products and supplements may increase risk, whereas another more recent study showed no increased risk of prostate cancer associated with total calcium, dietary calcium or supplemental calcium intakes.

Until more is known about these possible risks, it's important to be careful to avoid excessive amounts of calcium. As with any health issue, it's important to talk to your doctor to determine what's right for you.

Several different kinds of calcium compounds are used in calcium supplements. Each compound contains varying amounts of the mineral calcium — referred to as elemental calcium. Common calcium supplements may be labeled as:

  • Calcium carbonate (40 percent elemental calcium)
  • Calcium citrate (21 percent elemental calcium)
  • Calcium gluconate (9 percent elemental calcium)
  • Calcium lactate (13 percent elemental calcium)

The two main forms of calcium supplements are carbonate and citrate. Calcium carbonate is cheapest and therefore often a good first choice. Other forms of calcium in supplements include gluconate and lactate.

In addition, some calcium supplements are combined with vitamins and other minerals. For instance, some calcium supplements may also contain vitamin D or magnesium. Check the ingredient list to see which form of calcium your calcium supplement is and what other nutrients it may contain. This information is important if you have any health or dietary concerns.

When looking at calcium supplements, consider these factors:

Amount of calcium

Elemental calcium is key because it's the actual amount of calcium in the supplement. It's what your body absorbs for bone growth and other health benefits. The Supplement Facts label on calcium supplements is helpful in determining how much calcium is in one serving. As an example, calcium carbonate is 40 percent elemental calcium, so 1,250 milligrams (mg) of calcium carbonate contains 500 mg of elemental calcium. Be sure to note the serving size (number of tablets) when determining how much calcium is in one serving.

Tolerability

Calcium supplements cause few, if any, side effects. But side effects can sometimes occur, including gas, constipation and bloating. In general, calcium carbonate is the most constipating. You may need to try a few different brands or types of calcium supplements to find one that you tolerate the best.

What prescriptions you take

Calcium supplements can interact with many different prescription medications, including blood pressure medications, synthetic thyroid hormones, bisphosphonates, antibiotics and calcium channel blockers. Depending on your medications, you may need to take the supplement with your meals or between meals. Ask your doctor or pharmacist about possible interactions and which type of calcium supplement would work for you.

Quality and cost

Manufacturers are responsible for ensuring that supplements are safe and claims are truthful. Some companies have their products independently tested by U.S. Pharmacopeial Convention (USP),  ConsumerLabs.com (CL) or NSF International (NSF). Supplements that bear the USP, CL or NSF abbreviation meet voluntary industry standards for quality, purity, potency, and tablet disintegration or dissolution. Different types of calcium supplements have different costs. Comparison shop if cost is a factor for you.

Supplement form

Calcium supplements are available in a variety of forms, including tablets, capsules, chews, liquids and powders. If you have trouble swallowing pills, you may want a chewable or liquid calcium supplement.

Absorbability

Your body must be able to absorb the calcium for it to be effective. All varieties of calcium supplements are better absorbed when taken in small doses (500 mg or less) at mealtimes. Calcium citrate is absorbed equally well when taken with or without food and is a form recommended for individuals with low stomach acid (more common in people over 50 or taking acid blockers), inflammatory bowel disease or absorption disorders.

Dietary calcium is generally safe, but more isn't necessarily better, and excessive calcium doesn't provide extra bone protection.

If you take calcium supplements and eat calcium-fortified foods, you may be getting more calcium than you realize. Check food and supplement labels to monitor how much total calcium you're getting a day and whether you're achieving the RDA but not exceeding the recommended upper limit. And be sure to tell your doctor if you're taking calcium supplements.

Aug. 05, 2015