Calcium is essential not only for the formation and strength of bones, but it also fulfills other important functions in your body. Calcium is needed for blood clotting, blood pressure control, enzyme activation, contraction and relaxation of muscles (including the heart), and nerve transmission.
Along with this mineral you need vitamin D to maintain levels of calcium in your body. Without vitamin D, dietary calcium is poorly absorbed from the intestines. Vitamin D also strengthens the immune system. Although vitamin D is found naturally in only a few foods, products such as milk, yogurt, cereal and orange juice are fortified with the vitamin; this is how many people meet their vitamin D requirement. Vitamin D is also produced in the body with exposure to sunlight.
Many experts are concerned about the growing problem of vitamin D deficiency in the United States. People 50 and up are at risk for a deficiency because their bodies aren’t able to produce as much of the vitamin as they age. Dark-skinned people and those who live in northern parts of the United States, where sunlight is reduced, also make less vitamin D and are at risk for a deficiency. Most people eventually need to take a calcium/vitamin D supplement to meet their daily recommended intake.
Protection against osteoporosis
An adequate intake of calcium and vitamin D helps protect against the development of osteoporosis, which causes bones to become porous, brittle and susceptible to fractures. While postmenopausal women are at highest risk, men are also susceptible to osteoporosis, particularly after age 65.
When blood levels of calcium are too low, calcium is released from your bones (99 percent of the calcium in your body resides in your bones). Your bones are constantly broken down and rebuilt throughout your life. This turnover becomes a problem only when calcium loss in the urine outpaces calcium intake, because the body must then sacrifice bone to maintain blood calcium levels for other crucial functions. Over time, a deficit in dietary calcium can result in osteoporosis.
Here’s how to make sure you get what you need every day:
1. Increase your intake of calcium-rich foods. After age 50, women’s calcium requirement increases to 1,200 mg per day to maintain bone mass and prevent osteoporosis. Men should consume 1,200 mg per day after age 70. Foods rich in calcium include dairy products such as milk, yogurt and cheese. Aim for three cups per day. Choosing fat-free or low-fat dairy products will minimize your intake of cholesterol and saturated fats. Nondairy sources of calcium include calcium-fortified juices, and canned salmon with the bones.
2. Ask your doctor if you should take a calcium supplement. It’s best to meet your calcium requirements with food, but if you cannot consume enough through your diet, you may want to take a calcium supplement. However, it’s important to talk to your doctor first. Some recent studies suggest that calcium supplements—but not calcium-containing foods—may increase the risk of cardiovascular disease.
The most common calcium supplements are calcium carbonate and calcium citrate. Calcium citrate is better absorbed than calcium carbonate in people who have decreased stomach acid (as can occur with aging) and can be taken on an empty stomach, but it can be more expensive. Calcium carbonate must be taken with food to ensure full absorption.
When buying a calcium supplement, consult the label to see how much elemental calcium it contains; this is defined as the amount of calcium available for absorption from each tablet. Forty percent of a calcium carbonate tablet consists of elemental calcium, and 20 percent of a calcium citrate tablet is elemental calcium. Therefore, a 500-mg calcium carbonate tablet will provide 200 mg of elemental calcium, and you need to take five to six tablets to reach your daily requirement. Since calcium citrate products have less elemental calcium than calcium carbonate supplements, you’ll need to take more pills. Check with your doctor to make sure you’re taking the right dose (not too much or too little).
3. Avoid taking all of your calcium at once. Calcium—whether obtained from supplements or dietary sources—is best absorbed when consumed several times a day in amounts of 500 mg or less.
4. Get enough vitamin D. The recommended daily intake for vitamin D is 600 international units (IU) for adults under age 71 and 800 IU for those 71 and over. Fortified foods and beverages such as milk, soy milk and margarine are good sources of vitamin D. The vitamin also occurs naturally in a few foods, including fish, liver and egg yolks. Getting 10 to 15 minutes of sunlight without wearing sunscreen several times a week is another way to meet your vitamin D requirement. (This shouldn’t increase your risk of skin cancer if you don’t exceed the recommended time frame. But if you have had skin cancer in the past, check with your doctor before doing this.) Most older adults cannot get enough vitamin D through food and sunlight and need to take a supplement; discuss with your doctor the best way for you to meet your needs.
5. Be sure your calcium and vitamin D intake isn’t too high. Be careful not to exceed a maximum daily limit of 4,000 IU of vitamin D and 2,000 mg of calcium. As more people take supplements and eat foods that have been fortified with these nutrients, it’s possible that some could be consuming too much. Excessive calcium from dietary supplements has been associated with kidney stones, and too much vitamin D can damage the kidneys.