Encyclopedia of Diets - A Guide to Health and Nutrition

cheddar cheese, 1.5 ounces: 305 mg

mozzarella cheese, 1.5 ounces: 372 mg

sardines with bones, canned in oil, 3 ounces: 324

salmon with bones, canned, 3 ounces: 181 mg

tofu, firm, made with calcium sulfate, 1/2 cup: 204 mg

pinto or red beans, cooked, 1/2 cup: 43 mg

white beans, cooked, 1/2 cup: 113 mg

bok choy, 1/2 cup cooked: 61 mg

spinach, cooked, 1/2 cup: 120 mg

bread, whole wheat, 1 slice 20 mg

orange juice, fortified, 6 ounces: 200–260 mg

instant breakfast drink, powder prepared with water,

105–250 mg

breakfast cereal, fortified, 1 cup: 100–1,000 mg

Although experts recommend that people meet as

many of their vitamins and minerals needs through diet

as possible, it is difficult for many people to get enough

calcium from food alone. This is especially true for

vegans, who eat no dairy products, adolescent girls

who are very calorie conscious and tend to avoid milk

and replace it with diet sodas, and people with lactose

intolerance who cannot easily digest dairy products.

Pregnant women and older individuals may also have

a hard time eating enough to meet their calcium needs.

People who do not get enough calcium through diet can

benefit from taking a dietary supplement containing

calcium.

Calcium supplements are available over-the-counter.

The most common supplements supply calcium in the

form of calcium carbonate or calcium citrate. Calcium

carbonate is usually the most economical calcium supple-

ment. People who are taking medications to reduce stom-

ach acid may more easily absorb calcium citrate. Some

supplements combine calcium andvitamin Dbecause

vitamin D helps the body absorb calcium. No calcium

supplement contains enough calcium meet the entire daily

adequate intake, because the pill would be too large to

swallow. In addition, the body absorbs calcium best in

doses of 500 mg or less. People who need more than 500

mg of supplemental calcium should divide the dose in half

to be taken morning and evening.

Calcium deficiency

Calcium deficiency, called hypocalcemia, can

occur because of inadequate calcium intake, excess

calcium excretion by the kidney (usually caused by

kidney damage), the inability to adequately absorb

calcium, or because of interactions between calcium

and some prescription drugs. People at highest risk of

calcium deficiency are teenagers, women past the age

of menopause, individuals who are lactose intolerant,

vegans, and people with kidney (renal) damage.

Calcium deficiency rarely shows up in blood tests

because calcium is withdrawn from the bones to main-

tain blood levels of calcium. The bones then become

less dense, weaker, and more likely to break. This con-

dition is calledosteoporosisand it is most noticeable in

the elderly who have a high rate of broken bones result-

ing from falls. Osteoporosis is a part of aging, but

eating a healthy diet high in calcium, getting adequate

vitamin D, and doing weight-bearing exercises regu-

larly can delay its onset. Severe calcium deficiency, is

usually caused by a medical condition rather than inad-

equate calcium intake. It causes symptoms such as

muscle cramps, tingling in the fingers, lethargy, convul-

sions, heart rhythm abnormalities, and death. These

symptoms can also be caused by many other diseases.

Calcium excess

Calcium excess is called hypercalcemia. It usually

results from poor kidney function (renal failure) or

from a malignantcancertumor. It can also be caused

by very large supplemental doses of vitamin D. Very

rarely is hypercalcemia caused by too much calcium

from food ordietary supplements.Highlevelsofcal-

cium interfere with the absorption of other minerals

such asiron,zinc,magnesium, and phosphorous. Peo-

ple with hypercalcemia usually have multiple medical

problems and are under the supervision of a physician.

Precautions

People of all ages, races, and gender need to be

alert to getting enough calcium in their diet. Building

strong, dense bones begins in childhood and adoles-

cence, even though the results cannot be seen until old

age. People mentioned above as being at especially

high risk of low dietary calcium intake should inves-

tigate taking a calcium supplement.

Interactions

Absorption of calcium is affected by several

conditions.

 Age. Infants absorb as much as 60% of the calcium

in their digestive system. This decreases to 15–20% in

adulthood, and even less in old age.

Pregnancy. Pregnancy increases the efficiency of cal-

cium absorption in the intestine to meet the demands

of fetal development.

Amount of calcium consumed. The more calcium con-

sumed at one time, the less efficient absorption

Calcium