Transcript Calcium in the Diet

Chapter 11
MAJOR MINERALS
AND BONE HEALTH
Minerals in the Body
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Minerals are elements needed by the body in
small amounts for health and maintenance.
Major minerals are needed in the diet in
amounts greater than 100 mg per day or are
present in the body in amounts greater than
0.01% of body weight.
Trace minerals are required in the diet in
amounts less than 100 mg per day or are
present in the body in amounts less than
0.01% of body weight.
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Minerals
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Minerals in the Diet
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Calcium, Magnesium and Phosphorus Intake of
Canadians
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Mineral Talk
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Minerals are available in unprocessed foods, some processed
foods and dietary supplements.
To maintain health, minerals must be consumed in the correct
proportions.
Bioavailability is very important. For example, phytates can
limit the body’s ability to absorb calcium, zinc and iron.
DRIs for minerals are expressed as RDAs, EARs or AIs.
Because certain minerals can be toxic if taken in too high an
amount, ULs have been established.
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Minerals as Cofactors
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Calcium in the Diet
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Calcium in the Diet (continued)
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Intake of soft drinks is affecting the calcium intake of
teenagers. Canadian adolescent males (14–18 years)
consume an average of 376 ml/day of regular soft drinks
and adolescent girls consume 179 ml/day.
Milk intake declines with age.
Teenage boys consume 323 ml/day; girls, 222 ml /day.
Young men (19–30 years) consume 201 ml/day; young
women, 178 ml/day.
Men over 70 consume 136 ml/day; women, 136 ml/day.
Canada’s Food Guide recommends 3 servings of milk or
milk products/day to ensure adequate calcium intake.
(Intake as milk would be 750 ml/day).
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Calcium in the Diet (continued)
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Soft drinks are replacing milk, have no
calcium and are higher in sugar.
Low calcium intake early in life increases the
risk of osteoporosis and increases the
number of overweight and obese individuals.
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Calcium in the Diet (continued)
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You can determine if a packaged food is a good
source of calcium by looking at the label.
The Nutrition Facts panel lists the amount of calcium
in mg and as % of Daily Value.
The product label may have a nutrient content claim.
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Calcium in the Diet (continued)
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A multivitamin and mineral supplement will not
provide enough calcium to meet your needs.
Read labels to find a supplement that contains
calcium alone or calcium with Vitamin D (which aids
in absorption of calcium).
The form of calcium is also important. Calcium
carbonate should be taken with a meal, whereas
calcium citrate can be taken at any time.
Antacids that contain aluminum and magnesium
may actually increase calcium loss.
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Calcium Talk
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Calcium is the most abundant mineral in the body.
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Calcium provides the structure to bones and teeth and
has important regulatory roles.
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Calcium is absorbed by active transport and passive
diffusion, depending on the availability of the active form
of vitamin D.
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Bioavailability of calcium is decreased in the presence of
tannins, fiber, phytates and oxalates.
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Calcium accounts for 1–2% of adult body weight.
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Calcium’s Role in the Body
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99% of calcium in the body is found in solid
mineral deposits in the bones and teeth.
The remaining 1% is found in intracellular
fluid, blood and extracellular fluid.
Calcium found in the body’s fluid plays a role
in nerve transmission, muscle contractions,
blood pressure regulation and the release of
hormones.
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Regulation of Blood Calcium
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Calcium and Bone Health
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Risk Factors for Osteoporosis
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Osteoporosis
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Osteoporosis is a major public health
problem in Canada.
Two million Canadians over age 50 have
osteoporosis. Twice as many women as men
have the condition.
Osteoporosis is responsible for 80% of
fractures in people over 60 years of age.
Osteoporosis and fractures cost the
Canadian health care system $1.9 billion
annually to treat.
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Osteoporosis Risk
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Gender and Bone Mass
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Phosphorus in the Diet
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Phosphorus Talk
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Phosphorus makes up about 1% of an adult’s body.
85% of phosphorus in the body is found in the
bones and teeth.
Phosphorus is more readily absorbed than calcium.
Phosphorus is an important component of molecules
with structural or regulatory roles.
Phosphorus deficiency can lead to bone loss,
weakness and loss of appetite.
Phosphorus toxicity is rare, but can lead to bone
resorption.
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Magnesium in the Diet
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Magnesium Talk
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About 50-60% of magnesium in the body is found in bone,
where it is essential for the maintenance of structure.
Most of the remaining magnesium is present inside cells,
where it is the second most abundant intracellular ion, after
potassium.
Magnesium is a cofactor for over 300 enzymes. It is
necessary for the generation of energy from carbohydrate,
lipid and protein.
Magnesium deficiency is rare. When it does occur, especially
in individuals with alcoholism, malnutrition, kidney and GI
disease or in people taking diuretics, it may cause nausea,
muscle weakness and cramping, mental derangement and
changes in blood pressure and heartbeat.
Magnesium toxicity is rare. The UL for adults has been set at
350 mg from nonfood sources of magnesium.
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Sulfur Talk
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Dietary sulfur is found in protein foods and sulfurcontaining amino acids in vitamins.
Dietary sulfur is also found in nonfood additives, such as
sulfur dioxide, sodium sulfite and sodium bisulfite.
Sulfur-containing amino acids, such as methionine and
cysteine, are needed for protein synthesis.
The vitamins thiamin and biotin contain sulfur.
There is no recommended daily intake for sulfur.
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Summary of Calcium, Phosphorus, Magnesium
and Sulfur
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Copyright
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