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Calcium - The "Supernutrient"
Calcium
is the first nutrient approved by the FDA for the prevention
of a specific disease. The "supernutrient"
status of calcium stems from its potential to reduce the risk of
osteoporosis, hypertension, colon cancer and other diseases.
Calcium is
essential to life. Not only is it the principal mineral in bones and
teeth, but calcium is also involved in blood clotting and muscle
contraction, among other functions. All of these processes require
maintenance of a constant level of blood calcium. Bone is the body's
calcium reserve. When dietary calcium intake is low, skeletal reserves of
calcium are drawn upon. Any depletion of bone calcium results in a
corresponding reduction in bone's mechanical strength and eventually
increased fracture risk.
High Blood Pressure
(hypertension)
Since the
mid-1980s, there has been accumulating evidence that a dietary pattern low
in fat and rich in low-fat dairy foods, fruits and vegetables reduces
blood pressure. A blood pressure reduction occurs often within two
weeks that is comparable to that achieved with drugs. In addition, the
blood pressure-lowering effect of a low-fat diet is often independent of
sodium intake and changes in body weight. Researchers estimate that if the
general population were to adopt such a diet, the decrease in blood
pressure alone would reduce stroke by 27% and coronary heart disease by
15%.
Osteoporosis
It is important to
understand that bone is not a hard and lifeless structure; it is, in fact,
complex, living tissue. Our bones provide structural support for muscles,
protect vital
organs and store the calcium essential for bone density and strength.
Because bones are constantly changing, they can heal and may be affected
by diet and exercise. Until the age of about 30, you build and store bone
efficiently. Then, as part of the natural aging process, your bones begin
to break down faster than new bone can be formed. In women, bone loss
accelerates after menopause, when your ovaries stop producing estrogen -
the hormone that protects against bone loss.
Think of your
bones as a savings account.
There is only as much bone mass in your account as you
deposit. The critical years for building bone mass are from prior to
adolescence to about age 30. Some experts believe that young women can
increase their bone mass by as much as 20 percent - a critical factor in
protecting against osteoporosis. A balanced diet rich
in calcium and vitamin D,
combined with weight-bearing exercise is highly recommended.
Colon Cancer
A
protective role for calcium against colon cancer is demonstrated in
several different types of scientific studies. Extensive data indicate
that calcium reduces abnormal cell proliferation in the colon. A recent
investigation of over 800 adults at risk for colon cancer because of
removal of adenomatous polyps (i.e., precursors of colon cancer) from the
colon found that adding 1200mg calcium per day to their diet reduced colon
polyp adenomas by 19 to 24%.When patients at risk of colon cancer consumed
an additional 800mg calcium per day from lowfat dairy foods (i.e., a total
dietary intake of 1500mg calcium per day), several early markers of colon
cancer were reduced. This beneficial effect was greater than expected from
the level of calcium provided. The researchers speculated that other
components in dairy foods may work together with calcium to produce
these positive effects.
Dietary Calcium
Calcium-rich foods include foods from the Milk
Group (e.g., milk, yogurt, cheese). Green leafy vegetables, calcium-set
tofu, shellfish, crustaceans and a few nuts are other calcium-containing
foods. Food sources of calcium are usually good sources of other essential
nutrients. This is why diets low in calcium are generally low in several
other essential nutrients. For individuals who cannot meet all of their
calcium needs from foods naturally containing this nutrient, fortified
foods (e.g., breakfast cereals, bread, pasta)
calcium supplements are advisable.
Supplement -
Calcium Carbonate - There are several
different forms of calcium available. Each form has a
different degree of solubility and absorption. Older people often have a
stomach acid deficit or take drugs such as Prilosec that block stomach
acid production. Individuals with insufficient stomach acid output have been
shown to absorb only about 4% of calcium carbonate supplements. Even
people with normal levels of stomach acid only absorb about 22% of calcium
carbonate supplements. Most commercial calcium preparations (including
"oyster shell" calcium) and OTC anti-acid products contain
lower-cost calcium carbonate.
Supplement -
Calcium Citrate
Malate - A form of calcium called calcium
citrate is more effective at getting
into the bloodstream. While people with insufficient stomach acid output
absorb only
about 4% of calcium carbonate supplements, they can absorb
up to 45% of calcium citrate supplements. While calcium citrate is superior to
most commercial
calcium supplements, there is another form of calcium that has even better
solubility
and absorption. When
the chelating agent malic acid is added to calcium
citrate, calcium citrate malate is created, a compound that is 10 times more
soluble than calcium citrate.
Recommendations
- The government has established new goals for the daily intake of
calcium for men and women. Called AI (Adequate Intake), the figures
below supplant the old RDA (Recommended Daily Allowance) and represent
the amount of daily calcium that all individuals in the following age
groups should try to meet: For men and women ages 50 to 70: 1,200 mg a day. For men and women ages 19 to 50: 1,000 mg a day.
- Your body can't absorb more than about 500 mg of
calcium at a time, so divide a daily dose of 1,000 mg, for example, into
two doses of 500 mg and take them at different times of the day.
- In addition, when calculating your dose, make sure to look at the
amount of "pure" or "elemental" calcium, not just the weight of each
pill. The packaging will usually provide this information. For example,
a 600 mg calcium carbonate tablet contains 240 mg of elemental calcium.
- The absorption of zinc, iron, and magnesium may be hindered by
calcium, particularly when calcium is taken in high doses. Take a
multimineral supplement to ensure balanced absorption of these other
nutrients.
- Calcium carbonate may cause gas and constipation in some cases. If
this happens, switch to calcium citrate. This should resolve the
problem.
- Take calcium with food--it's best absorbed that way. Orange juice
and other foods with calcium citrate mixed right in can now easily be
found on grocery store shelves.
- Avoid calcium supplements made from bone meal, oyster shells, or
dolomite; they may contain high levels of lead.
- People over age 65 are advised to use calcium citrate because they
may not have enough stomach acid to absorb calcium carbonate.
- Don't consume calcium within one to three hours of taking an
antibiotic such as doxycycline, minocycline, or tetracycline. It may
decrease the absorption of the drug.
- If you use thiazide diuretics, consult your doctor before taking
calcium supplements. When taken together, they can cause dangerously
high calcium levels in the body, possibly resulting in kidney failure.
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Sources: |
| 1. University of Oregon
Health Sciences |
| 2. Columbia University
College of Physicians & Surgeons |
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Vision & Health Newsletter courtesy of:
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Dr. Philip Smith & Associates
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1855 1st Ave #100 San Diego, CA 92101
619-297-4331 |
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