Importance
of CALCIUM
Calcium is important
for overall health. Almost every cell in our body uses calcium in some way.
Some areas where our bodies use calcium is in our nervous system, muscles,
heart and bone. Our bones store calcium in addition to providing support for
our bodies. In fact, 99% of the body’s calcium is found in bones and teeth (the
other 1% is found in cells, blood, and other body fluids). As we age, we absorb
less and less calcium from our diet, causing our bodies to take more and more
calcium from our bones. Over time this aging process can cause or contribute to
osteopenia (reduced bone mass or density) or osteoporosis (bones become brittle
and fragile from loss of bone tissue), which is a more severe form of
osteopenia.
Function
Calcium is one of the most important minerals for the human
body. Calcium helps form and maintain healthy teeth and bones. Despite its
static appearance, bone is constantly being formed and broken down. This
process, called remodeling, is the resorption (breaking down) of existing bone
and deposition of new bone to replace that which has been broken down. Proper levels of calcium over a lifetime can
help prevent osteoporosis.
Calcium helps your body with:
- Building
strong bones and teeth
- Clotting
blood
- Sending
and receiving nerve signals
- Squeezing
and relaxing muscles
- Releasing
hormones and other chemicals
- Activation
of enzyme reactions
- Keeping
a normal heartbeat
In general, from birth until about age 20, the bones are in
a phase of active growth. This stage is characterized by an increase in bone
length and bone width. Shaping of the growing bones, called modeling, also
occurs at this time. Between the ages of 12 and 30, the rapid phase of bone
dimensional growth tapers off and consolidation occurs with the attainment of
peak bone mass. It is generally accepted that peak bone mass or maximum bone density
and strength occurs by age 30. Beginning in the 40s or later, resorption of
existing bone starts to exceed formation of new bone, resulting in a net loss.
Calcium also is important for the development of teeth.
Teeth, like bones, are calcified tissues. The teeth begin to form in the first
few months of fetal life and the mineralization process continues into late
adolescence. An adequate intake of calcium, in addition to phosphorus, protein,
fluoride, and vitamins A, C, and D, is needed for proper development of tooth structures.
Calcium and calcium-rich dairy products such as milk and cheese may help
protect against dental caries and periodontal diseases.
Food Sources
CALCIUM AND DAIRY PRODUCTS
Many foods contain calcium, but dairy products are the best
source. Milk and dairy products such as yogurt, cheeses, and buttermilk contain
a form of calcium that your body can absorb easily.
Whole milk (4% fat) is recommended for children ages 1 to 2.
Adults and children over the age of 2 should drink low-fat (2% or 1%) or skim
milk and other dairy products. Removing the fat will not lower the amount of
calcium in a dairy product.
- Yogurt,
most cheeses, and buttermilk are excellent sources of calcium and come in
low-fat or fat-free versions.
- Milk
is also a good source of phosphorus and magnesium, which help the body
absorb and use calcium.
- Vitamin
D is needed to help the body use calcium. Milk is fortified with vitamin D
for this reason.
OTHER SOURCES OF CALCIUM
Green leafy vegetables such as broccoli, collards, kale,
mustard greens, turnip greens, and Chinese cabbage are good sources of calcium.
Other sources of calcium that can help meet your body's
calcium needs:
- Salmon
and sardines canned with their soft bones
- Almonds,
Brazil nuts, sunflower seeds, and dried beans
- Blackstrap
molasses
Calcium is added to several food products, such as orange
juice, soy milk, ready-to-eat cereals, and breads. These are a very good source
of calcium for persons who do not eat a lot of dairy products or who are on a
vegan diet.
Ways to make sure you receive or absorb the calcium in your
diet:
- Cook
foods in a small amount of water for the shortest possible time to keep
more calcium in the foods you eat.
- Be
careful about what you eat with calcium-rich foods. Certain fibres, such
as wheat bran and foods with oxalic acid (spinach) can bind with calcium
and prevent it from being absorbed.
DIETARY SUPPLEMENTS
Calcium is also found in many multivitamin-mineral
supplements. The amount varies depending on the supplement. Dietary supplements
may contain only calcium or calcium with other nutrients such as vitamin D.
Check the label on the Supplement Facts panel to determine the amount of
calcium. Calcium absorption is best when taken in amounts of no more than 500
mg at a time, excess of this will be excreted from the body. This can be taken
twice daily to reach the 1000mg daily allowance.
Two commonly available forms of calcium dietary supplements
include citrate and carbonate.
- Calcium
citrate- It is taken up well by the body on a full or empty stomach.
- Calcium
carbonate- It is absorbed better by the body if taken with food.
Other types of calcium in supplements and foods include
lactate, gluconate, and phosphate.
Side Effects
Increased calcium
for a limited period of time does not normally cause side effects. However,
receiving higher amounts of calcium over a long period of time raises the risk
of kidney stones in some people.
Those who do not
receive enough calcium over a long period of time can develop osteoporosis.
Other disorders are also possible.
Persons with lactose
intolerance have trouble digesting lactose, the sugar in milk. Over-the-counter
products are available that make it easier to digest lactose. You can also buy
lactose-free milk at most grocery stores.
Tell your health
care provider about any dietary supplements and medicines you take. Your
provider can tell you if those dietary supplements might interact or interfere
with your prescription or over-the-counter medicines. In addition, some
medicines might interfere with how your body absorbs calcium.
Recommendations
The preferred source
of calcium is calcium-rich foods such as dairy products. Some people will need
to take calcium supplements.
The Recommended
Dietary Allowance (RDA) for vitamins and minerals reflects how much of each
vitamin or mineral most people should get each day. The RDA for vitamins and
minerals may be used to help create the goal for each person.
How much calcium you
need depends on your age and gender. Other factors, such as pregnancy and
illnesses, are also important.
Infants (Adequate
Intake)
- 0 - 6 months: 200 milligrams per day
(mg/day)
- 7 - 12 months: 260 mg/day
Children and
Adolescents
- 1 - 3 years: 700 mg/day
- 4 - 8 years: 1,000 mg/day
- 9 - 18 years: 1,300 mg/day
Adults
- 19 - 50 years: 1,000 mg/day
- 50 - 70 years: Men - 1,000 mg/day; Women
- 1,200 mg/day
- Over 71 years - 1,200 mg/day
Pregnancy and
Breast-feeding
- 14 - 18 years: 1,300 mg/day
- 19 - 50 years: 1,000 mg/day
Up to 2,500 - 3,000
mg a day of calcium from dietary sources and supplements appears to be safe for
children and adolescents, and 2,000 - 2,500 mg a day appears to be safe for
adults.
Note: Vitamin D is needed to
help the body absorb calcium. When choosing calcium supplements, look for ones
that also contain vitamin D.
References:
-
Medline Plus “Calcium in the Diet” US National
Library of Medicine.
-
Department of Medicine “Why is Calcium Important
“University of Wisconsin School of Medicine and Public Health.
-
National Dairy Council “Major Functions of
Calcium in the Body”
