Trace Minerals
The Trace Minerals
Main trace minerals (microminerals)
– Iron
– Copper
– Zinc
– Iodine
– Selenium
– Manganese
– Chromium
– Molybdenum
Less than 5g of in the body.
Daily needs less than 20mg.
Amount in plant foods depends on amount in soil.
Bioavailability can vary according to:
– Individual nutritional status
– Other foods eaten
– Form of the mineral
– Presence of other minerals
Minimal digestion required for absorption
– Some are recycled (such as iron).
Roles of Trace Minerals
Most function as Co-Factors!
Form part of an Enzyme Complex
Metalloenzymes: An enzyme that contains a metal
ion cofactor (for activity)
Many Also:
– Assist Hormone functions
– Provide structure of Bones and Teeth
– Maintain health of Red Blood Cells
– Component of Antioxidants
Deficiencies and Toxicity - difficult to determine.
Recommended intakes UL’s difficult to establish.
Iron (Fe)
Most abundant mineral on Earth and the most
abundant trace mineral in the body
Iron deficiency = most common nutrient
deficiency in world.
Iron-deficiency anemia common in women and children
80% of iron
consumed in
foods
Two forms of iron:
Heme iron
Non-heme iron
Heme Iron
Heme Iron is in
Hemoglobin and
Myoglobin and
Cytochromes
Found in animal foods
Meat, poultry, fish
Ferrous iron Fe2+
Glycated Hemoglobin = HbA1c (sugar coated Hb!)
Advanced Glycation End-products (AGE’s)
Diabetes Mellitus = higher glycated Hb’s – this is assoc with:
Cardiovascular Disease, Nephropathy and Retinopathy.
Heme
containing
cytochrome!
Iron Absorption and Transport
Non- heme Iron is in
Plant foods - Grains, vegetables
Ferric iron Fe3+
Absorption-Transport mechanism
of iron is tightly controlled to
prevent toxicity.
Iron Bioavailability
Factors:
Molecular form: = ferrous iron (Fe+2) or ferric iron (Fe+3)
Iron status of individual
Types of food eaten at the same time
Heme iron 2-3 X more bioavailable than non-heme iron.
Non-heme iron binds to:
– Oxalates (leafy vegetables)
– Polyphenols (tea and coffee)
Non-heme iron ↑ absorption:
– Vitamin C
– Meat, fish, and poultry (MFP) factor
Best Dietary
Sources of Iron
Hormone Hepcidin controls Iron absorption
Inhibits ferroportin from transporting iron out of the
enterocyte (gut cell) into the portal blood
Fe Stores:
Low iron stores increase intestinal iron absorption.
High iron stores decrease intestinal iron absorption.
Excess iron is excreted in the feces.
Iron Recycling
95% of iron in body recycled and reused!
*Iron from degraded hemoglobin is salvaged.
This is used to make new Red Blood Cells, incorporated
into enzymes, stored in ferritin
Most iron losses occur from bleeding.
E Metabolism - Part of cytochromes in mitochondria
Immune function – For production of lymphocytes
and macrophages
Protects cell membranes from free radical damage
Participates in oxidation-reduction reactions
Fe & Brain Function - helps enzymes of neurotransmitters
Dopamine, epinephrine, norepinephrine and serotonin.
Adult Females: 19-50: 18 mg/day, older: 8 mg/day
Adult Males: 8 mg/day
Vegetarians needs 1.8 times higher iron levels.
Those with Liver disease cannot
store as much iron in the body
Iron Toxicity
From supplements or in individuals with the
genetic disorder hemochromatosis too much
dietary iron absorbed.
Symptoms =
constipation, nausea, vomiting, and diarrhea.
UL: 45 mg/day
Accidental ‘overdose’ of supplements with iron
leading cause of poisoning deaths in children
under age 6.
Iron overload = Buildup of excess stores of iron
over years. Can damage organs and tissues
Hemochromatosis can cause overload.
May stimulate free radical production
Iron Deficiency
Iron-deficiency anemia
– Hemoglobin levels decrease
– Oxygen delivery to tissues diminished
Symptoms =
fatigue, weakness, ↓ability to fight infection.
Copper (Cu)
2 Forms of Copper in Body
– The oxidized form: Cupric (Cu2+)
– The reduced form: Cuprous (Cu+)
Absorbed in small intestine (based on ‘need’)
Very little stored in the body
Bioavailability is enhanced by Amino Acids.
Phytates, zinc, & other trace minerals ↓ bioavailability
Metabolic Functions of Copper
Metalloenzymes and Proteins component
oxidation reactions and reducing free radical damage
Part of enzyme that reduces iron to ferric form
Functions of Copper
• E Production
• Links the proteins collagen and elastin together
in connective tissue
• Synthesizes Melanin
• Part of superoxide dismutase, helping protect
against free radical damage
• Role in blood clotting & healthy immune system
Adults: 900 μg/day; UL: 10,000 μg/day
Copper Toxicity and Deficiency
Toxicity – causes stomach pains and cramps,
nausea, diarrhea, vomiting, and liver damage
Deficiency – Rare* - Fatigue and weakness
*Premature infants fed formulas
Genetic Disorders of Copper Metabolism
Menkes Disease
Copper transport disorder - Accumulation can cause:
developmental problems, osteoporosis, cardiovascular
disease and death.
Wilson's Disease
Prevents excretion of copper through the bile
Accumulation can cause liver and brain damage.
Zinc
2+
(Zn )
Very small amounts in almost every cell of body
Mostly bone & muscle
Involved in the function of more than 100
metalloenzymes, for protein synthesis
Absorption in small intestine, bound and stored
metallothionine.
Zinc in blood is bound to albumin.
Excess Zn is excreted in the feces.
Absorption is ↓ when:
1) High levels of non-heme iron are present
2) Phytates and diets high in fiber are consumed
Eating animal proteins ↑ Zn absorption.
Zinc Recycling
Part of Pancreatic Juices – reabsorbed by intestine.
• Zinc is recycled and reused by pancreas.
Zinc not reused is excreted in feces.
Small losses in urine, sweat, sloughed-off skin and hair
Functions of Zinc
Wound Healing
Maintains healthy Immune System
Acts as an antioxidant
Reduces inflammation
DNA and RNA synthesis - Turns genes on and off
Part of enzymes/proteins for skin repair
Enhanced Skin and Hair Cell Proliferation
Improves Taste Perception!
Reduces Macular Degeneration
Zinc Toxicity: UL 40 mg/day
Stomach pain, nausea, vomiting, and diarrhea
Excess can:
• Interfere with Copper absorption
• Suppress the immune system Adult Zn Needs:
• Lower HDL cholesterol
8 to 11 mg/day
Zn Deficiency:
Delayed growth in children; delayed sexual maturation
Hair loss, Skin rash
Loss of Appetite; Impaired sense of taste
Diarrhea
Impotence
Selenium (Se)
Seleno-proteins (enzymes) and Seleno-methionine (in diet)
Absorption based on ‘need’.
Stored in variety of tissues - Kidney maintain homeostasis
Metabolism of Selenium
Functions of Selenium
Se - Regulates Thyroid hormones
Antioxidant role - helps fight cancer
Glutathione Peroxidase:
Prevents free radical damage
Slows tumors and may reduce death rate from
lung, colon, and prostate cancer
Adults: 55 μg/day
Se Toxicity
UL: 400 μg/day => “Selenosis”
Brittle nails and hair, which may fall out
+ GI tract discomfort, skin rash, garlicky breath,
fatigue, nervous damage
Se Deficiency
May trigger Keshan disease (congestive cardiomyopathy)
Possible changes in thyroid hormone
Chromium (Cr)
Trivalent chromium (Cr3+) active form in food.
Very little chromium is absorbed.
Stored in a variety of tissues.
Excreted in the urine, ↑ with high sugar intake.
Functions of Cr
Increases insulin effectiveness in cells
May improve insulin's effects on metabolism
and storage of energy-yielding nutrients
May improve blood glucose levels in individuals
with Diabetes Mellitus or Pre-Diabetes
May prevent or improve Metabolic Syndrome
Food
Chromium
Source
(µg/100 g)
Mussel
128
Brazil nut
100
Oyster
57
Date (dried)
29
Pear
27
Brown shrimp
26
Wholemeal flour
21
Tomato
20
Mushroom
17
Broccoli
16
Barley
13
(wholegrain)
Hazelnut
12
Pork chop
10
Adults: 20 to 35 μg/day
Cr Toxicity - No known risks from foods or
supplements
May ↓ absorption, transportation, and utilization
of iron by binding to transferrin
Cr Deficiency
Rare in U.S. - May ↑ blood glucose and fatty acids
Iodine (I)
Iodide (ionic form) of iodine = essential mineral.
Metabolic Functions of Iodine
Thyroid gland traps iodide to make hormone
thyroxine (T4), which converts to
triiodothyronine (T3).
Functions of Iodine
Thyroid Hormones Regulate:
– Metabolism - Basal Metabolic Rate (BMR)
– Reproduction
– Energy Production in the TCA cycle
– Nerve, Muscle, and Heart Function
Adults: 150 μg/day: UL: 1,100 μg/day
Amount consumed in food depends on the amount of
iodine in soil, water, and fertilizer used to grow foods.
I Toxicity
Impairs thyroid function and ↓synthesis and release of
thyroxine
I Deficiency
Simple Goiter: Enlarged thyroid gland
Secondary Goiter – from Goitrogens: Substances in food
that reduce the use of iodine by thyroid gland, resulting
in goiter: Rutabagas, cabbage, soybeans, and peanuts
Iodine Toxicity and Deficiency
Deficiency
During pregnancy
Damage to brain of the
developing baby
Cretinism
(congenital hypothyroidism)
Abnormal sexual development
Mental retardation
Dwarfism
Manganese (Mn)
Part of, or activates, many enzymes in body
Mostly found in bones and accessory organs of
the digestive tract.
Metabolic functions
Cofactor for a variety of metallo-enzymes for
Metabolism of Carbs, Fats and Amino Acids
Formation of bone matrix
Helps build cartilage supporting the joints
Mn Daily needs - Adults: 1.8 to .3 mg/day
Food Sources:
Whole grains
Nuts
Legumes
Tea
Vegetables
Fruits
Mn Toxicity
– Exposure to environmental pollutants
Symptoms:
Damage to Nervous System
Symptoms resembling Parkinson's Disease
Mn Deficiency - Rare
– Phytates, calcium, and iron can ↓absorption.
– Rash and scaly skin
Molybdenum (Mo)
Function: Cofactor for many metallo-enzymes
Involved in metabolism of certain Amino Acids
Oxidation-Reduction reactions
Daily needs: Adults: 45 μg/day
Foods:
Legumes, grains,
Nuts, Dairy products
Leafy green vegetables
Mo Toxicity
Shown to cause reproductive problems and kidney
disorders in animals
UL: 2 mg/day
Mo Deficiency
Not seen in
healthy individuals