When you think of nutrition
and bone health, calcium naturally comes to mind. Although
getting sufficient calcium is essential to strong bones,
the amount you consume isn't the only issue. Your intake
of protein and fat also has a profound effect on calcium
metabolism.
The Role of Calcium
Calcium is the most plentiful mineral in the human body.
Most of it (99%) is stored in your bones and teeth-the
remainder is found in blood. When your calcium intake
isn't sufficient, your body may take this mineral from
your bones in order to maintain the necessary calcium
level in your blood.
You get calcium from the food you eat and, sometimes,
from supplements. The best dietary sources of calcium
are dairy foods. You also get calcium when you eat dark
green leafy vegetables (kale, collards, turnip greens,
and broccoli), soybeans, sardines and salmon, clams,
and oysters. How much calcium do you need each day?
Several years ago a panel from the National Institutes
of Health (NIH) established the following recommended
levels of calcium for optimum bone health, that is,
to reduce your risk of osteoporosis.
How much calcium do you need each day? Several years
ago a panel from the National Institutes of Health (NIH)
established the following recommended levels of calcium
for optimum bone health, that is, to reduce your risk
of osteoporosis.
Optimal Intake of Calcium at Different Ages
| |
Infant |
|
| |
Birth-6 months |
400
|
| |
6 months - 1 year |
600
|
| |
Children |
|
| |
1-5 years |
800
|
| |
6-10 years |
800-1,200
|
| |
Adolescents/Young
Adults |
|
| |
11-24 years |
1,200-1,500
|
| |
Men |
|
| |
25-65 years |
1,000
|
| |
Over 65 years |
1,500
|
| |
Women |
|
| |
25-50 years |
1,000
|
| |
Over 50 (postmenopausal) |
1,500
|
| |
 On
estrogens |
1,000
|
| |
Not
on estrogens |
1,500
|
| |
Over 65 years |
1,500
|
| |
Pregnant and nursing |
1,200-1,500
|
Adapted from reference 2
The Role of Protein
You can't assume that all the calcium you get in foods
and supplements is available to help build and maintains
bone. After all, calcium is constantly being excreted
by the kidneys
and lost from the body. The calcium that actually remains
in your body and is available to be utilized is key
to bone health.
Your protein intake from animal sources affects the
amount of calcium you excrete in urine. A high protein
diet increases calcium loss. The more protein
you eat above the amount required for normal body functioning,
the harder it is to maintain calcium balance (the amount
of calcium going into and leaving your body are equal).
If you ate only 50 grams of protein, it's estimated
that you could have a positive calcium balance-less
calcium being lost than being consumed-on as little
as 500-600 milligrams (mg) of calcium per day.
However, most Americans consume much more than 50 grams
of protein, which may help explain why the current calcium
recommendations for adults are much higher than 600
mg. On the other hand, protein intake below the amount
required by your body for normal functioning can also
be a risk factor for osteoporosis.
Hormone Status and Bone Health
Estrogen has a protective effect on bone. One reason
menopausal women are sometimes advised to use Estrogen
Replacement Therapy (ERT) or Hormone
Replacement Therapy (HRT) is to avoid the rapid
loss of bone mass that typically begins at menopause.
However, many women choose not to use ERT or HRT. One
survey of more than 7,500 American women (age 65 and
older) found that only 17.4% were currently using ERT,
27.2% had used it in the past but had discontinued the
therapy, and 55.4%- more than half the women- had never
used ERT.
This low usage of ERT and HRT isn't unique to American
women. A survey of HRT use was conducted in nearly 1,500
women (age 40-55) in France, Germany, Spain, and the
United Kingdom. The researchers found that about one-third
of perimenopausal
women and 13% of postmenopausal women were currently
taking HRT. Approximately one-fourth of postmenopausal
women reported taking HRT at one time.
References
View
bone health references list.
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