Transcript Trace Minerals

Trace Minerals
The Trace Minerals--An Overview
► Trace
minerals are needed in very small
(trace) quantities in the human body. They
perform many essential functions important
to health.
► Toxic levels can easily be reached with the
use of supplements.
► Humans can get the amounts of trace
minerals needed by consuming a wide
variety of foods.
The Trace Minerals--An Overview
► Food




Sources
Depends on soil and water composition
Depends on processing
Bioavailability
Wide variety of unprocessed foods
The Trace Minerals--An Overview
► Deficiencies
 Severe deficiencies of some minerals are easy
to recognize, while others can be difficult to
diagnose.
 Mild deficiencies are easily overlooked.
 Deficiencies have wide-reaching effects.
 Deficiencies affect all ages, but in children, they
can affect growth.
The Trace Minerals--An Overview
► Toxicities
 Do not exceed Tolerable Upper Intake Levels.
 FDA does not limit amounts in supplements.
 Do not exceed 100% Daily Values.
► Interactions
 Common and coordinated to meet body needs
 Can lead to nutrient imbalances
Iron
► Iron
is an essential nutrient found in the body as a
part of hemoglobin and myoglobin.
► Iron is used for energy metabolism and enzyme
activity.
► Special proteins assist with iron absorption,
transport, and storage.
► Both iron deficiency and iron toxicity cause
damage so balance is important.
► Heme iron is better absorbed but nonheme iron
absorption can be enhanced.
Iron Roles in the Body
 Cofactor in oxidation-reduction reactions
 Utilization of energy in cell metabolism
 Part of the protein hemoglobin which carries
oxygen in the blood
 Part of the protein myoglobin in the muscles
which makes oxygen available for muscle
contractions
Iron Absorption and Metabolism
 Iron Absorption
►The
protein ferritin stores iron in the mucosal
cells lining the digestive tract.
►Transfers iron to mucosal transferrin.
►Transfers iron to blood transferrin
►Transports iron to the cells
►Excreted and replaced as needed
Iron in food
Mucosal cells in the
intestine store excess
iron in mucosal ferritin
(a storage protein).
If the body
does not
need iron
Iron is not absorbed and is
excreted in shed intestinal
cells instead. Thus, iron
absorption is reduced when
the body does not need iron.
If the body
needs iron
Mucosal ferritin releases iron to
mucosal transferrin (a transport
protein), which hands off iron to
another transferrin that travels
through the blood to the rest of
the body.
Stepped Art
Fig. 13-1, p. 443
Iron Absorption and Metabolism
 Heme and Nonheme Iron
►Heme
iron
 Found in foods that are from the flesh of
animals (meat, poultry, and fish)
 Represents only 10% of a days iron
consumption, but has an absorption rate
of 25%
►Nonheme iron
 Found in plant-derived and animal-derived
foods
 Has an absorption rate of 17%
Only foods derived
from animal flesh
provide heme, but
they also contain
nonheme iron.
Key:
Heme
Nonheme
Heme accounts for about
10% of the average daily
iron intake, but it is well
absorbed (about 25%).
Nonheme iron accounts
for the remaining 90%,
but it is less well
absorbed (about 17%).
All of the iron in
foods derived from
plants is nonheme
iron.
Stepped Art
Fig. 13-2, p. 444
Iron Absorption and Metabolism
 Absorption-Enhancing Factors
 MFP factor
 When nonheme iron is consumed with
vitamin C at the same meal, absorption of
iron increases.
 Citric acid and lactic acid from foods, HCl
from the stomach, and sugars enhance
nonheme iron absorption.
Iron Absorption and Metabolism
 Absorption-Inhibiting Factors
►Phytates and fibers from legumes, grains, and rice
►Vegetable proteins in soybeans, legumes, and nuts
►Calcium in milk
►Tannic acid and other polyphenols in tea, coffee,
grains, oregano, and red wine
 Dietary Factors Combined
►Difficult to assess iron absorption with meal
consumption
►Most relevant factors are MFP factor and vitamin C
in enhancing absorption and phytates in inhibiting
absorption
Iron Absorption and Metabolism
► Individual
Variation
►Dietary
factors
►Health status
►Stage in life cycle
►Iron status
Iron Absorption and Metabolism
► Iron
Transport and Storage
►Surplus
is stored in bone marrow, spleen,
and liver
►Hemosiderin
is a storage protein used when
concentrations of iron are extremely high.
►Storing
excess iron is a protective measure
because iron can act as a free radical.
Iron Absorption and Metabolism
 Iron Recycling
►The liver and spleen dismantle red blood
cells and package iron into transferrin.
►Transferrin carries iron in the blood.
►Bone marrow incorporates iron into
hemoglobin and stores iron as ferritin.
►Iron-containing hemoglobin carries
oxygen in the blood.
►Iron is lost when bleeding occurs and
through the GI tract.
Some losses
via sweat, skin,
and urine
Transferrin carries
iron in blood.
Some iron
delivered to
myoglobin of
muscle cells
Liver (and spleen) dismantles
red blood cells, packages
iron into transferrin, and
stores excess iron in ferritin
(and hemosiderin).
Some losses
if bleeding
occurs
Bone marrow incorporates
iron into hemoglobin of red
blood cells and stores
excess iron in ferritin
(and hemosiderin).
Iron-containing
hemoglobin in
red blood cells
carries oxygen.
Stepped Art
Fig. 13-3, p. 445
Iron Deficiency
► Iron
deficiency is the most common
nutrient deficiency.
 Iron-deficiency anemia can affect individuals in
many stages of life.
 Vulnerable Stages of Life
► Women
in reproductive years due to menstruation
► Pregnant women due to the needs of the infant,
increases in blood volume, and loss of blood during the
birthing process
► Infants and young children due to rapid growth
► Teenagers due to rapid growth in males and
menstruation in females
Iron Deficiency
 Blood Losses
►Can be from non-obvious sources such as a
bleeding ulcer
►Malaria
and parasites
►Giving
a pint of blood results in a loss of
about 2.5 mg iron.
►Menstruation
Iron
► Iron
Deficiency
 Assessment of Iron Deficiency
►Stage
1 – Iron stores diminish; measured by
serum ferritin
►Stage
2 – Transport iron decreases; measured
by transferrin saturation
►Stage
3 – Hemoglobin production declines;
erythrocyte protoporphyrin accumulates and
hematocrit declines. Hemoglobin and
hematocrit are late indicators of iron status.
Iron
► Iron
Deficiency
 Iron Deficiency and Anemia
►Iron
deficiency is when there is depletion of
the body’s iron stores.
►Iron-deficiency
anemia is the severe depletion
of iron stores. Also called microcytic (small)
hypochromic (pale) anemia.
►Symptoms
include fatigue, weakness,
headaches, apathy, pallor and poor resistance
to cold temperatures.
Iron
► Iron
Deficiency
 Iron Deficiency and Behavior
►Energy metabolism is impaired.
►Neurotransmitter
synthesis is reduced.
►Physical
work capacity and mental
productivity are reduced.
►Symptoms
of a deficiency may be confused
with behavioral issues.
Iron
► Iron
Toxicity
 Iron Overload
►Hemochromatosis is generally a genetic
disorder that enhances iron absorption.
►Iron
overload can also be caused by:
 Repeated blood transfusions
 Massive doses of supplemental iron
 Rare metabolic disorders
Iron
► Iron
Overload
 Hemosiderosis may develop from excessive iron
where there are large deposits of hemosiderin in
the liver, heart, joints, and other tissues.
 Symptoms of iron overload include apathy,
lethargy, and fatigue.
 Problems include liver tissue damage and
infections.
 Higher risk of diabetes, liver cancer, heart
disease, and arthritis
 More common in men then in women
Iron
► Iron
Toxicity
 Iron and Heart Disease – may be a link to high
iron stores
 Iron and Cancer – may be a link with free
radical activity resulting in damage to DNA
 Iron Poisoning
►UL for adults: 45 mg/day
►Accidental supplement poisoning in children
►Symptoms include nausea, vomiting,
diarrhea, constipation, rapid heartbeat, weak
pulse, dizziness, shock, and confusion
Iron
► Iron
Recommendations and Sources
 Recommended Iron Intakes (2001 RDA)
►RDA
Men: 8 mg/day for adults 19-50 years of age
►RDA Women: 18 mg/day for adults 19-50 years of
age
►RDA Women: 8 mg/day for adults over 51 years of
age
►Vegetarians need 1.8 times as much iron because of
low bioavailability.
Iron
► Iron
Recommendations and Sources
 Iron in Foods
►Red meats, fish, poultry, and shellfish
►Eggs
►Legumes
►Grain products (whole-grain, enriched, and
fortified breads and cereals)
►Dark greens and dried fruits
 Iron-Enriched Foods
►Often added to grain foods
►Not absorbed as well
Iron
► Iron
Recommendations and Sources
 Maximizing Iron Absorption
►Bioavailability
is high in meats, fish, and poultry.
►Bioavailability is intermediate in grains and legumes.
►Bioavailability is low in vegetables.
►Combined effect of enhancing and inhibiting factors
Iron
► Iron
Contamination and Supplementation
 Contamination Iron
►Iron cookware takes up iron salts.
►Acidic foods and long cooking times increase
uptake of iron salts.
 Iron Supplements
►Best absorbable form is ferrous sulfate or an
iron chelate
►Take on empty stomach and with liquids other
than milk, tea, or coffee
►Vitamin C enhances food iron absorption, not
supplement absorption.
►Side effect of constipation
Zinc
Zinc is important in a multitude of chemical reactions
in the body.
► The best sources of dietary zinc are protein-rich
foods.
► Zinc from pancreatic secretions is also available for
absorption.
► Phytates and fiber can bind zinc, therefore limiting
absorption.
► A special binding protein monitors the absorption of
zinc.
► Zinc deficiency symptoms include growth retardation
and sexual immaturity.
►
Zinc
► Zinc
Roles in the Body
 Supports the work of metalloenzymes
►Helps
to make parts of DNA and RNA
►Manufactures heme for hemoglobin
►Assists in essential fatty acid metabolism
►Releases vitamin A from liver stores
►Metabolizes carbohydrates
►Synthesizes proteins
►Metabolizes alcohol
►Disposes of damaging free radicals
Zinc
► Zinc
Roles in the Body
 Involved in growth, development, and immune
function
 Affects platelets in blood clotting and wound
healing
 Needed to produce the retinal form of vitamin A
 Affects thyroid hormone function
 Influences behavior and learning performance
 Taste perception
 Wound healing
 Sperm development
 Fetal development
Zinc
► Zinc
Absorption and Metabolism
 Zinc Absorption
►Rate
of absorption depends on zinc status;
when more is needed, more will be absorbed.
►Phytates
and fiber bind zinc and reduce
absorption.
►Metallothionein
zinc in storage.
is a special protein that holds
Zinc
► Zinc
Absorption and Metabolism
 Zinc Recycling
►Enteropancreatic
circulation – travels from the
pancreas to the intestines and back
►Losses occur in the feces, urine, shedding of skin,
hair, sweat, menstrual fluids, and semen.
Zinc in food
Mucosal cells in
the intestine store
excess zinc in
metallothionein.
The pancreas uses
zinc to make digestive
enzymes and secretes
them into the intestine.
If the body
Zinc is not absorbed
does not
and is excreted in shed
need zinc
intestinal cells instead.
Thus, zinc absorption is
reduced when the body
does not need zinc.
If the body
needs zinc
Metallothionein releases
zinc to albumin and
transferrin for transport
to the rest of the body.
Stepped Art
Fig. 13-6, p. 453
Zinc
► Zinc
Absorption and Metabolism
 Zinc Transport
►Transported
►Binds
by the protein albumin
to transferrin
►Excessive
iron and copper can lead to a zinc
deficiency and excessive zinc can lead to an
iron and copper deficiency.
Zinc
► Zinc
Deficiency
 Not widespread
 Occurs in pregnant women, young
children, the elderly, and the poor
 Symptoms of deficiency
►Growth
retardation
►Delayed sexual maturation
►Impaired immune function
►Hair loss, eye and skin lesions
►Altered taste, loss of appetite, and delayed
wound healing
Zinc
► Zinc
Toxicity
 UL for Adults: 40 mg/day
 Symptoms
►Loss
of appetite
►Impaired immunity
►Low HDL
►Copper and iron deficiencies
►Vomiting and diarrhea
►Exhaustion
►Headaches
Zinc
► Zinc
Recommendations and Sources
 Recommended intakes (2001 RDA)
► RDA
Men: 11 mg/day
► RDA Women: 8 mg/day
 Zinc in foods
► Shellfish,
meats, poultry, milk, and cheese
► Whole grains and legumes
► Zinc
Supplementation
 Developing countries use zinc to reduce incidence of
disease and diarrhea.
 Zinc lozenges for the common cold are controversial and
inconclusive.
Iodine
► Iodide
is an essential component of the
thyroid hormone that helps to regulate
metabolism.
► Iodine deficiency can cause simple goiter
and cretinism.
► The iodization of salt has greatly reduced
iodine deficiency in the United States and
Canada.
Iodine
► Iodide
Roles in the Body
 Component of two thyroid hormones (T3 and
T4)
 Regulates body temperature, growth,
development, metabolic rate, nerve and muscle
function, reproduction, and blood cell
production.
Iodine
► Iodine
Deficiency
 Simple goiter is the enlargement of the thyroid
gland caused by iodine deficiency. Goiter is
enlargement of the thyroid gland due to
malfunction of the gland, iodine deficiency or
overconsumption of goitrogens.
 Goitrogen (antithyroid) overconsumption –
naturally occurring in cabbage, spinach, radishes,
rutabaga, soybeans, peanuts, peaches, and
strawberries.
 Cretinism is a congenital disease characterized
by mental and physical retardation and
commonly caused by maternal iodine deficiency
during pregnancy.
Iodine
► Iodine
Toxicity
 UL 1100 μg/day
 Symptoms include underactive thyroid gland,
elevated TSH, and goiter.
 Supplement use, medications, and excessive
iodine from foods
Iodine
► Iodine
Recommendations and Sources
 Recommendations (2001 RDA) – Adults: 150
μg/day
 Sources
►Iodized
salt
►Seafood
►Bread and dairy products
►Plants grown in iodine-rich soils
►Animals that feed on plants grown in iodine-rich soils
Selenium
► Selenium
is an antioxidant nutrient
associated with protein foods.
► It may provide some protection against
certain types of cancer.
► Selenium Roles in the Body
 Defends against oxidation
 Regulates thyroid hormone
Selenium
► Selenium
Deficiency
 Keshan disease – a pre-disposition to heart
disease where a virus causes the cardiac tissue
to become fibrous
 Prevalent in regions of China because the soil is
low in selenium
Selenium
► Selenium
and Cancer
 May protect against certain forms of cancer
 Inconclusive evidence and more research is
needed
 Food sources are better than supplements.
Selenium
► Selenium
Recommendations and Sources
 Recommendations (2000 RDA) – Adults: 55
μg/day
 Sources include seafood, meat, whole grains,
and vegetables (depends on soil content).
Selenium
► Selenium
Toxicity
 UL for Adults: 400 μg/day
 Symptoms
►Loss
and brittleness of hair and nails
►Skin rash, fatigue, irritability, and nervous system
disorders
►Garlic breath odor
Copper
► Copper
is a component of several enzymes
associated with oxygen or oxidation.
► Copper deficiency is rare.
► There are some diseases associated with
excessive intakes.
► Food sources of copper include legumes,
whole grains, and seafood.
Copper
► Copper
Roles in the Body
 Absorption and use of iron in the formation of
hemoglobin
 Part of several enzymes
 Some copper-containing enzymes are
antioxidants.
 Required for many metabolic reactions
Copper
► Copper
Deficiency and Toxicity
 Deficiency is rare in the U.S.; however, symptoms
include anemia and bone abnormalities.
 In Menkes disease, copper cannot be released into the
circulation.
 Toxicity
► UL
for Adults: 10,000 μg/day (10 mg/day)
► In Wilson’s disease, copper builds up in the liver and brain.
► Excessive intake from supplements can cause liver damage.
Copper
► Copper
Recommendations and Sources
 Recommendations (2001 RDA) – Adults: 900
μg/day
 Sources
►Seafood,
nuts, seeds and legumes
►Whole grains
►In houses with copper plumbing, water can be a
source.
Manganese
► Manganese
is a cofactor for several enzymes
involved in bone formation and various metabolic
processes.
► Deficiencies are rare and toxicities are associated
with environmental contamination.
► Manganese is found in many foods.
► Manganese Roles in the Body
 Cofactor for several enzymes
 Assists in bone formation
 Pyruvate conversion
Manganese
► Manganese
Deficiency and Toxicity
 Deficiency symptoms are rare.
 Phytates, calcium and iron limit absorption.
 Toxicity occurs with environmental
contamination.
 UL for Adults: 11 mg/day
 Toxicity symptoms include nervous system
disorders.
Manganese
► Manganese
Recommendations and Sources
 Recommendations (2001 AI)
►AI
Men: 2.3 mg/day
►AI Women: 1.8 mg/day
 Sources
►Nuts
►Whole
grains
►Leafy vegetables
►Tea
Fluoride
► Fluoride
makes bones stronger and teeth
more resistant to decay.
► The use of fluoridated water can reduce
dental caries.
► Excess fluoride causes fluorosis—the pitting
and discoloration of teeth.
Fluoride
► Fluoride
Roles in the Body
 Formation of teeth and bones
 Helps to make teeth resistant to decay
 Fluorapatite is the stabilized form of bone and
tooth crystals
 Fluoride and Dental Caries
►Widespread
health problem
►Leads to nutritional problems due to issues with
chewing
Fluoride
► Fluoride
and Toxicity
 Tooth damage called fluorosis – irreversible pitting and
discoloration of the teeth
 UL for Adults: 10 mg/day
 Prevention of fluorosis
► Monitor
fluoride content of local water supply.
► Supervise toddlers during tooth brushing.
► Watch quantity of toothpaste used (pea size) for toddlers.
► Use fluoride supplements only if prescribed by a physician.
Fluoride
► Fluoride
Recommendations and Sources
 Recommendations (1997 AI)
►AI
Men: 3.8 mg/day
►AI Women: 3.1 mg/day
 Sources
►Fluoridated
drinking water
►Seafood and tea
Chromium
► Chromium
is an essential nutrient that enhances
insulin’s action.
► It is widely available in unrefined foods.
► Chromium Roles in the Body
 Enhances insulin action
 Low chromium levels can result in elevated blood sugar
levels.
 Glucose tolerance factors (GTF) are small organic
compounds that enhance insulin’s action and some
contain chromium.
Chromium
► Chromium
Recommendations and Sources
 Recommendations (2001 AI)
► AI
Men: 35 μg/day
► AI Women: 25 μg/day
 Sources
► Meat,
especially liver
► Whole grains
► Brewer’s yeast
► Chromium
Supplements
 Claims about reducing body fat and improving muscle
strength remain controversial.
Molybdenum
► Molybdenum
is a cofactor in several enzymes.
► It is needed in minuscule amounts.
► It is available in legumes, grains, and organ
meats.
► Molybdenum functions as a cofactor for several
enzymes.
► No deficiency symptoms
► No reported toxicity symptoms in humans
Molybdenum
► Recommendations
(2001 RDA)
 Adults: 45 μg/day
 UL Adults: 2 mg/day
► Food
sources include legumes, grains, and
organ meats.
Other Trace Minerals
► Much
of the research on other trace
minerals is from animal studies.
► Humans need very small amounts.
► Determining exact needs, functions,
deficiencies, and toxicities is difficult.
► Some key roles of these other trace
minerals have been identified.
Other Trace Minerals
► Nickel
is a cofactor for certain enzymes.
► Silicon is used in bone and collagen formation.
► Vanadium is for growth, development, and
normal reproduction.
► Cobalt is a key component of vitamin B12.
► Boron may be key in brain activities.
► Arsenic is useful in some types of leukemia.
Contaminant Minerals
► Contaminate
minerals are also called heavy
metals.
► These include mercury, lead, and
cadmium.
► These minerals enter the food supply
through soil, water, and air pollution.
► They disrupt body processes and impair
nutrition status.
Contaminant Minerals
► Lead
toxicity symptoms in children
Learning disabilities in children
Low IQ
Behavior problems
Slow growth
Dental caries
Iron-deficiency anemia
Sleep disturbances like night walking, restlessness, and
head banging
 Nervous system disorders and seizures
 Slow reaction time and poor coordination
 Impaired hearing







Contaminant Minerals
► Lead
toxicity symptoms in adults
 Hypertension
 Reproductive complications
 Kidney failure
Phytochemicals and
Functional Foods
Phytochemicals and Functional
Foods
►
Phytochemicals are nonnutrient compounds.
►
Only a few of the thousands of phytochemicals have
been researched.
►
There are many questions and few answers about
their role in human health.
►
Foods that provide health benefits beyond those of
nutrients are now called functional foods.
►
Some have an identified role in disease prevention.
The Phytochemicals
► The
phytochemicals give foods taste,
aroma, color, and other characteristics.
► Defending against Cancer
 Phytoestrogens mimic estrogen
►Found
in soybeans, legumes, flaxseeds, whole
grains, fruits and vegetables
►Antioxidant activity
►Slow the growth of breast and prostrate
cancer
►Supplements may stimulate the growth of
cancers that depend upon estrogen.
The Phytochemicals
► Defending
against Cancer
 Lycopene
►Powerful
antioxidant
►Inhibits the growth of cancer cells
►Found in tomatoes and cooked tomato products,
apricots, guava, papaya, pink grapefruits, and
watermelon
 Five servings of fruits and vegetables are
recommended every day.
The Phytochemicals
► Defending
against Heart Disease
 Flavonoids in foods
►Powerful
antioxidants
►Protect against LDL cholesterol oxidation and
reduce blood platelet stickiness
►Lowers risk of chronic diseases
►Found in whole grains, legumes, soy,
vegetables, fruits, herbs, spices, teas,
chocolate, nuts, olive oil, and red wines
The Phytochemicals
► Defending
against Heart Disease
 Carotenoids in foods especially lutein and lycopene
►Lower risk of heart disease
►Found in fruits and vegetables
 Phytosterols
►May protect against heart disease
►Inhibit cholesterol absorption
►Lower blood pressure
►Act as antioxidants
►Found in soybeans and other vegetables
►Lignans, found in flax seed, are converted to
phytosterols by intestinal bacteria.
The Phytochemicals
► The
Phytochemicals in Perspective
 Difficult to assess one food and its benefits
alone
 Actions of phytochemicals are complementary
and overlapping
Functional Foods
► Foods
as Pharmacy
 Margarine enhanced with a phytosterol may
lower cholesterol.
 May be more useful in prevention and mild
cases of disease.
 Drugs are used for severe cases of disease.
Functional Foods
► Unanswered
Questions
 Research is lagging behind food manufacturers.
 Consumer questions to ask
►Does
it work?
►How much does it contain?
►Is it safe?
►Is it healthy?
Functional Foods
► Future
Foods
 Use of gene research
 Can we design foods to meet exact health
needs of each individual?
 Can farmers grow the “perfect” foods?