Transcript Nutrition11_Minerals

Major Minerals
Chapter 11
Major Minerals
• A major mineral is required in the diet and
present in the body in large amounts
compared with the trace minerals.
• Minerals are inorganic elemental atoms or
ions.
• Minerals are not changed during digestion or
when the body uses them.
Major Minerals
• Minerals are not destroyed by heat, light, or
alkalinity.
• Some minerals assist enzymes.
• Some minerals have structural roles.
Minerals In the Human Body
Minerals in Foods
• Foods from both plants and animals are
sources of minerals.
• Animal tissues contain minerals in the
proportions that animals need.
Minerals in Foods
• The mineral content of plants can vary
dramatically depending upon the minerals in
the soil where the plant is found.
• The maturity of the vegetable, fruit, or grain
can affect the mineral content.
Mineral Bioavailability
• The GI tract absorbs a much smaller
proportion of minerals than vitamins.
• Once absorbed, excess minerals are difficult
for the body to flush out.
• The body adjusts mineral absorption in
relation to needs.
Mineral Bioavailability
• Some minerals compete for absorption sites.
Megadosing with one mineral can impede
absorption of another.
• High-fiber diets reduce absorption of iron,
calcium, zinc, and magnesium.
• Phytate (a component of whole grains) binds
minerals and carries them out of the intestine
unabsorbed.
• Oxalate (found in spinach and rhubarb) binds
calcium, reducing its absorption.
Mineral Bioavailability
Sodium
• Sodium (Na) is an essential nutrient.
• Sodium is a component of sodium chloride
(table salt).
• Sodium in the diet is essential for normal body
function, but we shouldn’t eat too much salt.
• Major extracellular cation.
Sodium Functions
• Fluid balance. Maintains proper body water
distribution and blood pressure.
• Nerve transmission and muscle function.
• Control’s the body’s acidity.
Sodium Food Sources and
Recommended Intake
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Limit to 2,300 milligrams / day (DV)
Processed foods contribute the most sodium.
Table salt contributes some.
Sauces, pickled foods, salty meats, cheese, salted
snack foods, bouillon cubes, canned and instant
foods, and seasonings based on salt can all be high
sources.
• The GI tract absorbs nearly all dietary sodium.
• The kidneys excrete excess.
Sources of Dietary Sodium
Hyponatremia
• Hyponatremia – abnormally low sodium
concentrations in the blood due to excessive
excretion of sodium (by the kidenys),
prolonged vomiting, or diarrhea.
• Replacement of water without sodium.
Hyponatremia
• Symptoms of hyponatremia resemble
dehydration.
• Treatment involves replacement of fluids and
minerals through liquids and foods or
intravenous solutions if necessary.
Hyponatremia
• Severe hyponatremia causes extracellular fluid
to move into cells, causing them to swell.
• Brain cells swell – headache, confusion,
seizures, coma.
• Cancer, kidney disease, and heart disease can
cause hyponatremia.
Hypernatremia
• Hypernatremia – abnormally high sodium
concentrations in the blood due to increased
kidney retention of sodium or rapid ingestion
of large amounts of salt.
• Hypervolemia – an abnormal increase in the
circulating blood volume.
Hypernatremia
• Hypervolemia leads to edema (swelling) and a
rise in blood pressure.
• A healthy person with normal kidneys and
ample water intake rapidly excretes excess
sodium.
Hypernatremia
• Hypernatremia is seen in patients with
congestive heart failure and kidney disease.
• Eating too much sodium over a long period of
time can contribute to hypertension (high
blood pressure) in some people.
• Excess dietary sodium can contribute to
osteoporosis by increasing calcium loss in the
urine.
Exercise and Sodium Sensitivity
• A recent study sought to
examine if aerobic exercise
training in older people with
hypertension changes sodium
sensitivity with individuals
switching from sodium
sensitive to sodium resistant.
• The study was validated and
shows that that aerobic
training in older hypertensive
people can alter blood
pressure sensitivity.
ADA Dietary Guidelines for
Americans
• Consume less than 2,300 mg (approximately 1
teaspoon of salt) of sodium per day.
• Choose and prepare foods with little salt. At the
same time, consume potassium-rich foods, such as
fruits and vegetables.
• Key recommendations for Specific Population
Groups: Individuals with hypertension, blacks, and
middle-aged and older adults. Aim to consume no
more than 1,500 mg of sodium per day, and meet
the potassium recommendation (4,700 mg/day) with
food.
Potassium
• Major intracellular cation.
• If people with hypertension eat a diet rich in
potassium containing foods (fruits and
vegetables), their blood pressure often
improves.
Potassium Functions
• Muscle contractions
• Transmission of nerve impulses
• Helps regulate blood pressure
Potassium Food Sources and
Recommended Intake
• Fresh vegetables and fruits.
– Especially potatoes, spinach, melons, and
bananas.
• Fresh meat, milk, coffee, and tea also contain
some potassium.
Food Sources of Potassium
Hypokalemia
• Hypokalemia – low levels of blood potassium.
• Low intake can disrupt acid-base balance,
contribute to bone loss and kidney stones.
• Severe deficiency results from potassium
depletion (excessive losses).
– Prolonged vomiting, chronic diarrhea, laxative
abuse, use of diuretics.
• Risk factor for hypertension.
Hypokalemia
• People with poor diets, such as alcoholics and
individuals who suffer from anorexia nervosa
or bulimia nervosa, are at highest risk of
potassium deficiency.
• Athletes doing physical labor in high
temperatures have high water losses, so they
also risk potassium deficiency.
Hypokalemia Symptoms
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Muscle weakness
Loss of appetite
Confusion
Severe or rapid potassium depletion can
disrupt heart rhythms
Hyperkalemia
• Hyperkalemia – abnormally high blood
potassium.
• Malfunctioning kidneys or an excess of
intravenous potassium can cause
hyperkalemia.
• Hyperkalemia can slow and eventually stop
the heart.
Banana Facts
• You may know that bananas are high in
potassium, but did you also know that they
have an unusually high-carbohydrate content?
• Before ripening, a banana is almost entirely
starch. After ripening, certain varieties are
almost entirely sugar—as much as 20 percent
by weight.
Chloride
• Chloride (Cl-) – anion in table salt.
• Chlorine (Cl2) – poisonous gas – highly
reactive, used to treat water to kill bacteria
and other pathogens.
• Chloride is a major extracellular anion.
Chloride Functions
• Fluid balance.
• Combines with H+ to form HCl (hydrochloric
acid in the stomach).
• White blood cells use chloride to kill invading
bacteria.
• Assists in the transmission of nerve impulses.
Chloride Food Source
• Most of our chloride comes from salt.
• The kidneys secrete excess chloride and some
is lost in sweat.
• The only known cause of high blood chloride
is severe dehydration.
Hypochloremia
• Vomiting removes hydrochloric acid from the
stomach.
• Frequent vomiting (bulimia nervosa) can
cause a chloride deficiency.
• Frequent vomiting with inadequate fluid and
mineral consumption can lead to dehydration
and metabolic alkalosis (high blood pH).
Hypochloremia
• Metabolic alkalosis – abnormal pH of body
fluids usually caused by significant loss of acid
from the body or increased levels of
bicarbonate.
– Causes abnormal heart rhythm, substantial drop
in blood flow to the brain, decreased oxygen
delivery to the tissues, abnormal metabolic
activity.
– 5 percent rise in pH can be fatal.
Calcium
• About 1.5 to 2% of total body weight.
• Essential for healthy bones and teeth.
Calcium Functions
• Bones and tooth structure (99%) of calcium.
• Remaining 1% in blood and soft tissues.
– Muscle contraction.
– Nerve impulse transmission.
– Blood clotting.
– Cell metabolism.
Calcium Functions
Bone Structure
• Bone is made up of cells and an extracellular
matrix.
• Osteoblasts and osteoclasts continually
remodel our bones.
Bone Structure
• Osteoblasts secrete the collagen protein
matrix that forms the framework.
• Minerals in the form of hydroxyapatite
(calcium and phosphorus) surround the
collagen fibers.
• We achieve peak bone mass at around 30
years of age.
Calcium Food Sources
• Dairy products.
• Green leafy vegetables such as spinach have
high levels of calcium, but it is mostly bound
to oxalate and therefore cannot be absorbed.
• Chinese cabbage, kale, and turnip greens have
significant amounts of bioavailable calcium.
• Some food products are fortified with calcium.
Calcium Recommended Intake
• Adequate Intake (AI) for adults 19 to 50 –
1,000 milligrams per day.
• AI for adults aged 51 and older – 1,200
milligrams per day.
• AI for adolescents 9 to 18 – 1,300 milligrams
per day.
Regulation of Blood Calcium
• Circulating blood calcium performs many
essential functions; therefore, the body will
demineralize bone tissue to prevent even
minor changes in blood calcium.
• Three hormones regulate blood calcium:
– Calcitriol (active form of vitamin D)
– Parathyroid hormone
– Calcitonin
Regulation of Blood Calcium
• These hormones control intestinal absorption
of calcium, bone calcium release, and calcium
excretion by the kidneys.
• Inadequate calcium intake, high sodium
intake, excess caffeine, and other diuretics can
effect calcium balance by altering the
excretion of calcium in the urine.
Vitamin D (calcitriol – active form)
• Increases absorption of calcium into the
intestine.
• Increases the production of calcium binding
proteins in the small intestine.
Parathyroid Hormone
• Parathyroid Hormone (PTH) is secreted when
plasma calcium levels fall too low.
• PTH activates osteoclasts, which break down
bone and release calcium and phosphorus
into the blood.
• Increases kidney reabsorption of calcium.
• Increases phosphorus excretion.
• Stimulates calcitriol production.
Calcitonin
• The thyroid gland secretes calcitonin when
plasma calcium is too high.
• Acts in opposition to PTH.
• Weak effects on blood calcium.
• Inhibits formation and activity of osteoclasts.
• High calcitonin concentrations decreases PTH
production and thus decreases calitriol
production.
Calcium Absorption
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Between 25 to 75 percent of dietary calcium.
High during pregnancy and infancy.
Low during old age.
Requires adequate levels of vitamin D.
Inversely related to calcium intake.
Calcium Absorption
• Phytates (in nuts, seeds, grains) decrease absorption.
• Oxalates decrease absorption.
• High levels of phosphorus and magnesium decrease
absorption.
• Wheat bran decreases absorption (other dietary fibers
do not seem to decrease absorption).
• Low estrogen levels after menopause decrease
absorption.
• Calcium from supplements taken between meals and
at lower doses of 500 milligrams or less assists in
absorption.
Hypocalcemia
• Hypocalcemia – deficiency of calcium in the
blood.
• Rare because the body uses bone calcium to
maintain blood levels.
• Caused by kidney failure, parathyroid
disorders, and vitamin D deficiency.
Hypocalcemia
• Can cause muscle spasms, facial grimacing,
and convulsions.
• Chronic dietary deficiency causes
osteoporosis.
• Increased risk of hypertension, colon cancer,
and preeclampsia.
Hypercalcemia
• Major Causes
– Cancer
– Overproduction of PTH by the parathyroid gland
Hypercalcemia
• Clinical Signs and Symptoms
– Fatigue
– Confusion
– Loss of appetite
– Constipation
– Calcium may be deposited in the soft tissue where
it can impair organ function.
Excess Calcium Supplementation
• Excess calcium supplementation usually does
not result in hypercalcemia, but may cause
mineral imbalances by interfering with the
absorption of other minerals, such as iron,
magnesium, and zinc.
• Calcium supplements that contain citrate and
ascorbic acid enhance iron absorption, but
other forms cut iron absorption in half.
Phosphorus
• Widespread in the food supply.
• Phosphorus is the most abundant intracellular
anion.
Phosphorus Functions
• Phosphorus plays an important role in bone as
part of the mineral complex hydroxyapatite.
• Phosphorus helps activate and deactivate
enzymes in a process known as
phosphorylation.
• Essential component of ATP.
• Component of DNA, RNA, and phospholipids
in cell membranes and lipoproteins.
Phosphorus Food Sources and
Recommended Intake
• Phosphorus is abundant in the food supply.
• Foods rich in protein (milk, meat, eggs) are
also rich in phosphorus.
• Food additives in processed meats and sodas
contain phosphorus.
• RDA for adults is 700 milligrams per day.
Adolescents need about 1,250 milligrams per
day.
Hypophosphatemia
• Phosphorus is so abundant in foods that only
near-total starvation will cause a dietary
deficiency.
Hypophosphatemia
• Underlying disorders affect absorption or
excretion and cause hypophosphatemia.
– Hyperparathyroidism (often due to a tumor)
– Vitamin D deficiency
– Overuse of aluminum, magnesium, or calcium
containing antacids that bind phosphate.
Hypophosphatemia
• Clinical Signs and Symptoms
– Anorexia
– Dizziness
– Bone pain
– Muscle weakness
– Waddling gait
Hypophosphatemia
• Chronic
– Affects the musculoskeletal system causing muscle
weakness and damage including respiratory
problems due to poor diaphragm function.
• Long-standing
– Can cause rickets and osteomalacia
Hyperphosphatemia
• Causes
– Kidney disease
– Underactive parathyroid gland
– Too many vitamin D supplements
– Overuse of phosphorus containing laxatives
– Excessive dietary intake (i.e. too much soda)
Hyperphosphatemia
• Clinical signs and symptoms
– Excessive phosphorus can bind calcium
– Low calcium can cause nerve fibers to discharge
repeatedly without provocation. This can lead to
muscle spasms and convulsions.
– Excess phosphorus and not enough calcium can
lead to increased bone loss.
– Increased phosphorus intake may lead to
osteoporosis later in life.
Magnesium
• Magnesium (Mg)
• 50 – 60% is in bone, remainder distributed
between muscle and other soft tissues.
• Most resides in cells. Only 1% is extracellular.
Magnesium Functions
• Participates in more than 300 types of
enzyme-mediated functions.
• Assists in DNA synthesis.
• Assists in protein synthesis.
• Assists in energy production in the ETS and
glycolysis.
• Participates in muscle contraction.
• Participates in blood clotting.
Magnesium Recommended Intake
• RDA for adults 19 – 30 years 400 mgs / day for
men and 310 mgs / day for women.
• Ages 31-70 -- 420mg / day men 320 mg / day
women.
Magnesium Food Sources
• Dietary intake comes primarily from plants.
• Whole grains and vegetables such as spinach
and potatoes are goods sources.
• Legumes, tofu, and some seafood.
• Sesame seeds, cashews, almonds.
• Processed grains lose up to 80 % of the
magnesium and enrichment does not replace
Magnesium Food Sources
• “Hard” water can contain some magnesium.
• High-fiber diets often have a negative effect
on mineral absorption.
• High calcium intake from supplements can
interfere with magnesium absorption.
Hypomagnesemia Causes
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Kidney disease
Associated with alcoholism
Diuretic drugs
Prolonged diarrhea
Chronically poor diets
Mineral Deficiencies
• Deficiency in any of the three major
intracellular minerals (magnesium, potassium,
and phosphorus) usually is associated with
deficiencies of the other two.
Hypomagnesemia Clinical Signs
and Symptoms
• Healthy people whose diets are deficient in
magnesium usually have no signs or
symptoms for a few weeks because of the
large supply of magnesium stored in the bone.
• Short term deficiency:
– Loss of appetite, nausea, and weakness.
• Long-term deficiency:
– Muscle cramps, irritability, and confusion.
Hypomagnesemia Clinical Signs
and Symptoms
• Extreme:
– Death due to heart rhythm problems.
Hypermagnesemia
• Causes
– Uncommon in the absence of Kidney disease
– Use of magnesium containing antacids or laxatives
• Clinical Signs and Symptoms
– Nausea
– General weakness
Hypermagnesemia
• Physicians sometimes prescribe high doses
during pregnancy to stop premature labor
– Frequent monitoring is required to avoid toxicity
that can lead to respiratory paralysis
Sulfur
• Sulfur is not used alone as a nutrient.
• Sulfur is present in certain organic compounds
(vitamins biotin and thiamine and amino acids
methionine and cysteine)
• Disulfide bridges help proteins form their
tertiary and quartenary structures.
• Adequate protein intake ensures enough
sulfur. Deficiency is unknown in humans.
Hypertension
• Hypertension – high blood pressure.
• Major risk factor for heart disease, kidney
disease, and stroke.
• Genetic predisposition and high sodium diets.
• Excess weight tends to raise blood pressure.
• Exercise and weight loss tend to lower BP.
Hypertension
• Reducing alcohol tends to decrease BP.
• Diets rich in calcium, magnesium, and
potassium reduce blood pressure.
Osteoporosis
• Osteoporosis means “porous bone”.
• In osteoporosis, bone mass or density declines
and bone quality deteriorates.
Osteoporosis
• The bones become fragile and vulnerable to
fractures.
• Normal development and mineralization of
bones requires calcium, phosphorus, flouride,
magnesium, vitamin D, vitamin A, vitamin K,
and protein.