What You Should Know About Calcium

Why Is Calcium Important?

Calcium is a mineral that is essential for life, yet the majority of Americans do not get adequate calcium on a daily basis. Calcium plays an important role in building stronger, denser bones early in life and keeping bones strong and healthy later in life.

About 99 percent of the calcium in our bodies is found in our bones and teeth. In addition to building and maintaining healthy bones, calcium allows blood to clot, nerves to send messages, muscles to contract and other body functions.

Each day, our bodies lose calcium through skin, nails, hair, sweat, urine and feces. The human body cannot produce calcium on its own. That's why it's important to try to get enough calcium through the foods we eat. When the diet does not have enough calcium for our body's needs, calcium is taken from the bones.

Reading Food Labels

Sources of Calcium

Food remains the best source of calcium. Dairy products are high in calcium, while certain green vegetables and other foods contain calcium in smaller amounts.

For people who have trouble digesting dairy products because of lactose intolerance, lactose free dairy products and lactase enzyme pills are also available.

Calcium-fortified foods and calcium supplements are helpful for people who are unable to get enough calcium in their diets. Some juices, breakfast foods, soymilk, cereals, snacks, breads and bottled water have calcium that has been added. If you drink soymilk that is fortified with calcium, be sure to shake the container well as calcium can settle to the bottom.

Daily Calcium Recommendations

According to NOF recommendations:

• Adults under age 50 need a total of 1,000 mg of calcium from all sources and 400-800 IU of vitamin D daily.
• Adults 50 and over need a total of 1,200 mg of calcium from all sources and 800-1,000 IU of vitamin D daily.

People who get the recommended amount of calcium from foods do not need to take a calcium supplement. These individuals, however, still may need to take a vitamin D supplement.

Getting too much calcium may increase the chance of developing kidney stones in some people. According to most experts, the safe upper limit for total daily calcium intake from all sources is 2,000 - 2,500 mg.

Substances That Interfere with Calcium Absorption

There are several substances that can interfere with the body's ability to use calcium, including:

Foods with high amounts of oxalate and phytate reduce the absorption of calcium contained in those foods. Spinach, rhubarb and beet greens are examples of foods that are high in oxalate. While these foods can be an important part of a healthy diet, they are not good sources of calcium.

Legumes, such as pinto beans, navy beans and peas, are high in phytate. You can reduce the phytate level in beans or legumes by soaking them in water for several hours, discarding the water, and then cooking them in fresh water.

100% wheat bran is a food that provides fiber but is also high in phytate. It is the only food that appears to reduce the absorption of calcium in other foods eaten at the same time (for example, eating wheat bran cereal with milk). If you are taking calcium supplements, you may want to take them two or more hours before or after eating any foods with 100% wheat bran.

A diet that is too high in animal protein, sodium, and caffeine can decrease calcium absorption. A person’s daily calcium needs increase when they get too much protein and sodium. You can offset the calcium loss from caffeinated drinks such as coffee and tea by adding milk or extra calcium to your diet. If you consume any foods or drinks that may interfere with calcium absorption, you may want to take your calcium supplements at a different time of day.

Calcium Supplements

The amount of calcium needed from a supplement depends on how much you obtain from your food. If you get enough calcium from the foods you eat, then you don’t need to take a supplement. Taking more calcium than you need in supplements does not have added benefits.

Calcium exists in nature only in combination with other substances called compounds. Several different calcium compounds are used in supplements, including calcium carbonate, calcium citrate, calcium lactate and calcium phosphate. These compounds contain different amounts of elemental calcium, which is the actual amount of calcium in the supplement.

It is important to read the product label carefully to determine how much elemental calcium is in the supplement and how many doses or pills to take. When reading the label, pay close attention to the “amount per serving” and “serving size.”

Many people ask which calcium supplement they should take. The best supplement is the one that meets a person’s needs based on tolerance, convenience, cost and availability. Calcium supplements are available without a prescription in a wide range of preparations (including chewable and liquid) and in various strengths.

*NOF does not have specific vitamin D recommendations for these age groups. These are the recommendations of the American Academy of Pediatrics.

A Simple Way to Add Calcium to Many Foods

A single tablespoon of nonfat powdered milk contains about 50 mg of calcium. Try adding some to:

• Puddings
• Homemade cookies
• Breads or muffins
• Soups or gravy
• Casseroles

About two-to-four tablespoons can be added to most recipes!

Combination Products

Calcium supplements are also available in combination with vitamins and other minerals. Although vitamin D is necessary for the absorption of calcium, it does not need to be taken at the same time as a calcium supplement.

Minerals such as magnesium, phosphorus and vitamin K are also important for bone health, but are usually obtained by eating a well balanced diet. Most experts only recommend that people take multivitamins or supplements only when they are unable to get enough nutrients from foods.

Purity

Calcium supplements prepared from unrefined oyster shell, bone meal or dolomite may contain lead or other toxic metals. Choose supplements that are known brand names with proven reliability for these types of supplements.

If you are not familiar with the brand, look for labels that state "purified" or have the USP (United States Pharmacopeia) symbol. The "USP Verified Mark" on the supplement label means that the USP has tested and found the calcium supplement to meet certain standards for purity and quality. Because applying for the USP symbol is voluntary, many fine products may not display this symbol. The USP symbol is helpful when you don't know the brand.

Absorbability

The body easily absorbs most brand name calcium products. Calcium supplements need to dissolve in the stomach for calcium to absorb. Chewable and liquid supplements dissolve well because they break down before entering the stomach. The USP symbol on the label also lets you know that the supplement will break down and dissolve so that the body can use it.

Calcium, whether from diet or supplements, is best absorbed when taken in amounts of 500 – 600 mg or less. Taking your calcium all at once, however, is better than not taking it at all. Try to get your calcium-rich foods and/or supplements in smaller amounts throughout the day, preferably with a meal. Most calcium supplements should be taken with food. Eating food produces stomach acid that helps your body to absorb calcium. Supplements of calcium citrate absorb well taken at any time.

Tolerance

Side effects from calcium supplements, such as gas or constipation may occur. If increasing fluids and fiber in your diet does not solve the problem, try another type or brand of calcium. It may require trial and error, but fortunately there are many choices.

When starting a new calcium supplement, it may be better tolerated if you start with a smaller amount. For example, start with 200-300 mg of calcium a day for a week, and drink an extra 6-8 ounces of water with it. Then gradually add more calcium each week.

Calcium Interactions

Talk with your healthcare provider or pharmacist about possible interactions between prescription or over-the-counter medications and calcium supplements. Here are a few examples:

• Calcium supplements may reduce the absorption of the antibiotic tetracycline.
• Calcium supplements should not be taken at the same time as iron supplements.
• Thyroid hormones should not be taken within four hours of calcium supplements to prevent interactions (unless directed otherwise by a healthcare provider or pharmacist).
• Medications that need to be taken on an empty stomach should not be taken at the same time as a calcium supplement.

Also, consider calcium citrate supplements over other calcium supplements if you take proton pump inhibitors (PPIs) such as Prevacid®, Prilosec® and Nexium®. Because these medications block stomach acid, your body may better absorb calcium citrate which does not need stomach acid for absorption.

Summary

Most studies show that low calcium intake is associated with low bone mass, bone loss and higher fracture rates (broken bones). Getting enough calcium is one of the many things people can do to help reduce bone loss. People who get plenty of calcium during their lifetime may still be at risk for bone loss and osteoporosis due to a variety of factors. These factors include vitamin D deficiency, genetics (family history), physical inactivity, smoking, alcohol abuse, and certain medications and medical disorders known to cause bone loss.