Eating a diet that contains adequate amounts of calcium and vitamin D is key to maintaining strong bones. Muscles and nerves need calcium to work; when your diet doesn’t include enough calcium, your body takes the calcium it needs from your bones. Many Americans don’t consume enough dietary calcium or vitamin D, which the body needs to absorb calcium.
Foods such as milk, yogurt, and cheese are good sources of calcium. Low-fat and fat-free milk and yogurt contain the same amount of calcium as full-fat varieties, with fewer calories. Spinach and sweet potatoes also contain calcium, but the body absorbs the calcium in these foods less efficiently than it absorbs the calcium in milk. (You would need to eat 8 cups of cooked spinach to obtain the same amount of calcium found in an 8-ounce glass of milk.) Many products such as breakfast cereal and orange juice are fortified with calcium.
Because the body can absorb only about 500 mg of calcium at a time, it’s best to spread your calcium intake throughout the day. For example, try to eat at least one calcium-rich food at each meal. Adding a few tablespoons of nonfat powdered milk to soups, gravy, puddings, and home-baked bread and cookies is an easy way to add calcium to food (1 tablespoon adds 52 mg of calcium).
If you just can’t eat enough calcium-rich foods to get to 1,000 or 1,200 mg per day, talk to your doctor about taking a calcium supplement. If you decide to take a supplement, be sure to check whether it should be taken with food.
The Vitamin D Difference
Your body needs vitamin D to absorb calcium. The skin manufactures vitamin D when exposed to sunlight. Exposing the hands, arms, and face to the sun for 10 to 15 minutes two to three times a week without sunscreen enables the body to make enough vitamin D to meet its needs. Fair-skinned people make more vitamin D than dark-skinned people. Clothing, air pollution, window glass, the use of sunscreen, and the natural process of aging—all reduce the skin’s ability to make vitamin D.
People who spend a lot of time outdoors or who live at southern latitudes can usually make enough vitamin D through the skin to meet the body’s needs. Elderly people as well as people who don’t spend much time outdoors, who always use sunscreen, or who live at northern latitudes may need to take vitamin D supplements. Few foods naturally contain vitamin D, although some foods such as milk and breakfast cereal are fortified with it (see chart).
Recommended Calcium Intake*
|Children and adolescents|
|6 months-1 year||270|
|51 and older||1,200|
|Pregnant or breast-feeding women|
*National Academy of Sciences, 1997
Source: National Osteoporosis Foundation Web site. Available at http://www.nof.org/prevention/calcium.htm. Accessed October 3, 2007
Examples of Food Sources of Calcium
|Serving Size||Calcium (mg)||Calories|
|Squash (acorn or butternut, baked)||32||90|
|Sweet potato (baked)||32||90|
|Chick peas (canned)||38||142|
|Kidney beans (canned)||34||103|
|Fruit and fruit juice|
|Raspberries (fresh)||1 cup||27||60|
|Orange juice||8 ounces||22||112|
|Orange juice (calcium fortified)||300||112|
|Fish and shellfish|
|Rainbow trout||3 ounces||75||135|
|Sardines (with bones, canned)||4 pieces||242||100|
|Tuna (light, canned in water)||3 ounces||10||99|
|Blackstrap molasses||1 tablespoon||172||47|
|Soy milk (calcium fortified)||8 ounces||150–300*||108–130*|
*Varies by brand
Source: Calcium Content of Common Foods. Harvard University Web site. Available at: http://www.huhs.harvard.edu/HealthInformation/CalciumContent.htm. Accessed October 3, 2007.
Recommended Vitamin D Intake*
|Children and adolescents|
|Adults (including women who are pregnant or breast-feeding)|
|51 and older||800-1,000|
Source: Dietary Supplement Fact Sheet: Vitamin D. Office of Dietary Supplements, NIH Clinical Center, National Institutes of Health Web site. Available at: http://ods.od.nih.gov/factsheets/vitamind.asp#h3. Accessed October 3, 2007.
Tags: Nutritional Know-How