Chapter 13 NUTR

Chapter 13

The Trace Minerals

© 2009 Cengage - Wadsworth

The Trace Minerals--An
Overview
• Trace minerals are needed in very
small 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.


Overview
• Food Sources
Depends on soil and water
composition
Depends on processing
Bioavailability
Wide variety of unprocessed foods


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.


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
• Iron Roles in the Body
 Ferrous iron is reduced and has a net
positive charge of two.
 Ferric iron is oxidized and has a net positive
charge of three.
 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

• 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
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%


Iron

Absorption-Enhancing Factors
– MFP factor enhances the absorption of
nonheme iron.
– 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-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

Individual Variation
• Dietary factors
• Health status
• Stage in life cycle
• Iron status


Iron

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
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.


Iron

Iron Balance
• The absorption, transport, storage,
recycling, and loss of iron must be
regulated in order to maintain iron
balance.
• Hepcidin is a hormone that inhibits the
absorption and transport of iron to keep
blood levels within normal ranges.


Iron
• 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

• 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 Deficiency and Pica
• Generally found in women and children from low-
income groups
• Eating ice, clay, paste, and other nonfood
substances
• Eating nonfood substances will not correct the
deficiency.

Iron

• Iron Toxicity
Iron Overload
• Hemochromatosis is generally a genetic
disorder that enhances iron absorption
and may be caused by a lack of hepcidin.
• 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 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

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 is a special protein that
holds zinc in storage.


Zinc

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

Zinc Transport
• Transported by the protein albumin
• Binds 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: 4 mg/day
• AI Women: 3 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.


• 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


• 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?


Chapter 13 NUTR

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Chapter 13 NUTR