Calcium

• Calcium is the Key to Strong Bones
• Calcium Absorption Decreases With Aging
• Medications Can Interfere With Calcium Absorption
• Guidelines for Calcium Intake
• Dietary Sources of Calcium
• Calcium Supplements
  

Calcium is the Key to Strong Bones

Calcium is the major mineral in bone that makes it hard and strong. In order to reduce your risk for osteoporosis you need to maximize your bone mass as a young adult. As bone tissue is being dissolved and replaced, bone calcium is also being removed and replaced. As calcium is removed, it must be replaced by dietary calcium.

Calcium Absorption Decreases With Aging

Calcium is absorbed in the intestines. The intestines of very young individuals absorb about 75% of dietary calcium, this decreases to about 30 to 40% by adulthood. Older adults may absorb even less calcium from their diet. Postmenopausal women may absorb as little as 20% of dietary calcium (Wardlaw & Inslaw, 1996).

Medications Can Interfere With Calcium Absorption

Most older people do not get enough calcium from their diet. One reason is that certain medications can interfere with calcium absorption. For example:

• Corticosteroids (prescribed for conditions such as rheumatoid arthritis and ulcerative colitis) can decrease calcium absorption and increase calcium excretion in the urine.
• Thyroid hormone, when elevated, can interfere with calcium retention in the bones.
• Aluminum-containing antacids that are taken habitually cause excess loss of calcium in the urine.
• Certain anticonvulsants can cause a vitamin D deficiency which in turn affects calcium absorption.

The National Food and Nutrition Board of the National Academy of Sciences has established guidelines for calcium intake by age and gender. The upper limit for calcium is 2,500 mg a day because more than that can cause health problems. They recommend 1500 mg of calcium per day (about 5 glasses of milk) for older Americans. The average calcium consumption among American women is about 600 mg per day.

Dietary Sources of Calcium

The best sources of calcium are dairy products such as milk, cheese, and yogurt. Many vegetables (e.g., kale, collard, turnip, mustard greens) are good sources of calcium and calcium fortified foods include orange juice, bread, breakfast cereals and some snacks. An 8 ounce glass of milk contains 250 to 300 mg of calcium. Many people--especially African-Americans, Asians, and the elderly--do not have the lactase enzyme needed to digest milk. Fortunately, there are many lactose-free milk products, soy milk products (e.g., tofu), and calcium fortified orange juice that can be substituted. Sometimes, yogurt and cheese can be tolerated without problems.

Calcium Supplements

If you're not getting enough calcium in your diet then you may need calcium supplements. There are a lot of choices: calcium citrate, calcium carbonate, and calcium lactate. Older adults who have decreased stomach acidity should take either calcium carbonate with meals or calcium citrate between meals. Don't try to get all your calcium for the day all at once since your body cannot absorb more than 500 mg at one time.