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Transcript
MINERALS
Damion Francis MSc.
TMRI-ERU
Phosphorus
• 85% of phosphorus is located in bones
and teeth
• Remainder found in muscles, organs,
blood, and other fluids
• The mineral exist as an ion or in bound
form such as with phosphoprotein and
phospholipids
• majority of the phosphorus in the body is
found as phosphate (PO4)
Functions
• structural component of bone in the form of a
calcium phosphate salt called hydroxyapatite
• components of cell membranes
(phospholipids)
• All energy production and storage are
dependent on phosphorylated compounds
(ATP)
• maintain normal acid-base balance (pH)
Functions
• storage and transmission of genetic
information, in DNA and RNA
Metabolism
• Dietary phosphorus is readily absorbed in
the small intestine
• Excess is excreted by the kidney
• Regulation of blood calcium and
phosphorus levels is interrelated through
the actions of parathyroid hormone (PTH)
and vitamin D
• PTH increases urinary excretion of
phosphorus to balance calcium levels
Requirements
• RDA for phosphorus was based on the
maintenance of normal serum phosphate
levels in adults
• This represent adequate phosphorus
intake to meet cellular and bone formation
needs
• Requirement range from 700 – 1250
mg/day
Sources
• Phosphorus is found in most foods
• Dairy products, meat, and fish are good
sources
• phosphorus in all plant seeds (beans, peas,
cereals, and nuts) is present in a storage form
of phosphate called phytic acid or phytate
• Only about 50% of the phosphorus from
phytate is available to humans because we
lack the enzyme(phytases) that liberate it from
phytate
Toxicity
• The most serious adverse effect of abnormally
elevated blood levels of phosphate
(hyperphosphatemia) is the calcification of
non-skeletal tissues, most commonly the
kidneys
Deficiency
• The effects of hypophosphatemia may include
loss of appetite, anemia, muscle weakness,
bone pain, rickets (in children), osteomalacia
(in adults), increased susceptibility to infection,
numbness and tingling of the extremities, and
difficulty walking
Oral Implications
• Phosphorus deficiency has been
associated with incomplete calcification of
teeth
• Increased caries susceptibility during
development
• Increased vulnerability to periodontal
disease via effect on alveolar bone
Magnesium
• Magnesium plays important roles in the
structure and the function of the human
body
• The adult human body contains about 25
grams of magnesium.
• Over 60% of all the magnesium in the
body is found in the skeleton, about 27%
is found in muscle, while 6 to 7% is found
in other cells, and less than 1% is found
outside of cells
Function
• Activates more than 300 enzymes (energy
related)
• Regulates (Ca, K, and Na) transmission of
nerve impulses. Calcium contract muscles
and magnesium relax muscles
• Ensures proper DNA and RNA formation
and function
• Facilitates PTH secretion
Metabolism
• Healthy individuals absorbs 40-60%
magnesium consumed
• Absorption enhanced by calcium,
phosphorus and fat
• Longterm storage in the bones
• Kidney is the organ regulate magnesium
homeostasis
• 90% of filtered magnesium is reabsorbed
by the kidneys in response to salt and H20
reabsorption
Interactions
• High doses of zinc in supplement form appear to
interfere with the absorption of magnesium
• Calcitriol may increase the intestinal absorption of
magnesium to a small extent
• However, magnesium absorption does not seem to
be calcitriol-dependent as is the absorption of
calcium and phosphate.
• High calcium intake has not been found to affect
magnesium balance in most studies. Inadequate
blood magnesium levels are known to result in low
blood calcium levels, resistance to PTH, and
resistance to some of the effects of vitamin D
Oral Implications
• Magnesium deficiency related to increased
fragility of the alveolar bone
• Increase propensity for gingival
hypertrophy
Food Sources
• Magnesium is widely distributed in foods
• Most commonly found in plants containing
chlorophyll (dark green leafy vegetables)
• Whole grains and nuts are also a rich
source
• Animal products are lower in magnesium
Fluoride
• Fluorine occurs naturally in the Earth's
crust, water, and food as the negatively
charged ion, fluoride (F-)
• Fluoride is considered a trace element
because the daily requirement for
maintaining dental health is only a few
milligrams a day.
• About 95% of the total body fluoride is
found in bones and teeth
Fluoride
• its role in the prevention of dental caries
(tooth decay) is well established
• fluoride is not generally considered an
essential mineral element because
humans do not require it for growth or to
sustain life
• However, if one considers the prevention
of chronic disease (dental caries), an
important criterion in determining
essentiality, then fluoride might well be
considered an essential trace element
Function
• Fluoride is absorbed in the stomach and
small intestine
• Once in the blood stream it rapidly enters
mineralized tissue (bones and developing
teeth)
• At usual intake levels, fluoride does not
accumulate in soft tissue.
• The predominant mineral elements in
bone are crystals of calcium and
phosphate (hydroxyapatite)
• Fluoride's high chemical reactivity and
small radius allow it to either displace the
larger hydroxyl (-OH) ion in the
hydroxyapatite crystal, forming
fluoroapatite, or to increase crystal density
by entering spaces within the
hydroxyapatite crystal.
• Fluoroapatite hardens tooth enamel and
stabilizes bone mineral
Mechanism of action on Teeth
Preeruptive Sytemic Effects
– Fluoride is incorporated into developing
tooth’s mineralized structure
– Fluoride being more reactive exchange
with hydroxyl (OH) group in
hydroxyapatite (Ca10[PO4]6[OH]2) to
form fluoroapatite (Ca10[PO4]6F2) or a
mixed fluorohydroxyapatite
(Ca10[PO4]6FOH)
– The fluoride ion makes apatite crystals
less soluble and more resistant
Mechanism of action on Teeth
• Presence of fluoride in dental enamel
increase resistance to demineralization
after eruption
• Systemic fluoride during tooth formation is
no longer believed to provide the most
important benefit I preventing dental caries
Mechanism of action on Teeth
Posteruptive Effects
– Benefits of fluoride occurs primarily in fluid
phase at the tooth surface
– Fluoride decreases demineraization when
tooth is exposed to organic acids and for
increasing remineralization rate
– Interference in the formation and function of
dental plaque microorganism
– Increase rate of posteruptive maturation
– Improve tooth morphology (preeruptive)
Nutrient Interactions
• Calcium and magnesium form insoluble
complexes with fluoride decreasing
fluoride absorption when present in the
same meal
• Absorption of fluoride in the form of
monofluorophosphate (unlike sodium
fluoride) is unaffected by calcium
• diet low in chloride (salt) has been found
to increase fluoride retention by reducing
urinary excretion of fluoride
Requirements
• The Food and Nutrition Board (FNB) of the
Institute of Medicine recommendations for
fluoride intake in 1997
• inadequate data to set a RDA, instead
Adequate Intake levels were based on
estimated intakes (0.05 mg/kg of body
weight)
• shown to reduce the occurrence of dental
caries most effectively without causing the
unwanted side effect of tooth enamel
mottling known as dental fluorosis
Sources
• The fluoride content of most foods is low (less
than 0.05 mg/100 grams)
• Rich sources of fluoride include tea, which
concentrates fluoride in its leaves, and marine
fish that are consumed with their bones (e.g.,
sardines)
• Foods made with mechanically separated
(boned) chicken, such as canned meats, hot
dogs, and infant foods also add fluoride to the
diet
• Foods generally contribute only 0.3-0.6 mg of
the daily intake of fluoride