Transcript
The Trace Minerals
“Of special interest to...” symbol key: = Hot Topic = Personal Health
= Health Care Professionals = Science Majors
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.
A. Food Sources
Depends on soil and water composition
Depends on processing
Bioavailability
Wide variety of foods
B. Deficiencies
Mild deficiencies are easily overlooked.
Severe deficiencies are easy to recognize.
Deficiencies have wide-reaching effects.
Affects all ages
C. Toxicities
A person should not exceed Upper Level Recommended Intakes.
A person should not exceed 100% Daily Values.
FDA does not limit amounts in supplements.
Interactions
Common and coordinated to meet body needs
Can lead to nutrient imbalances
Iron
Iron is found in the body as part of the oxygen-binding proteins 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.
A. 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
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
Utilization of energy in cell metabolism
B. Iron Absorption and Metabolism
Iron Absorption
The protein ferritin stores iron in the mucosal cells. The mucosa is the lining of the digestive tract.
Transfers iron to mucosal transferrin.
Transfers iron to blood transferrin
Transports iron to the cells
Excreted and replaced as needed
Heme and Nonheme Iron
Heme iron
Foods that are flesh of animals
10% of days consumption
Absorption rate of 25%
Nonheme iron
Plant-derived and animal-derived foods
Absorption rate of 17%
Absorption-Enhancing Factors
MFP factor
Vitamin C
Citric acid and lactic acid from foods
HCl from stomach
Sugars
Absorption-Inhibiting Factors
Phytates and fibers from grains and vegetables
Oxalates from spinach, beets and rhubarb
Calcium and phosphorus from milk
EDTA (food additive)
Tannic acid and other polyphenols in tea and coffee
Dietary Factors Combined
Difficult to assess with meal consumption
Most relevant factors are MFP factor, Vitamin C and phytates
Individual Variation
Dietary factors
Health status
Stage in life cycle
Iron status
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 Recycling
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 with bleeding and through the GI tract.
C. Iron Deficiency
Vulnerable Stages of Life
Women in reproductive years
Pregnant women
Infants and young children
Teenagers
Blood Losses
Giving a pint of blood loses about 2.5 mg iron
Menstruation
Bleeding ulcers
Malaria and parasites
Assessment of Iron Deficiency
Stage 1 - Iron stores diminish; measure serum ferritin
Stage 2 – Transport iron decreases; measure transferrin saturation
Stage 3 – Hemoglobin production declines; erythrocyte protoporphyrin accumulates and hematocrit declines
Iron Deficiency and Anemia
Iron deficiency is depleted iron stores.
Iron-deficiency anemia is the severe depletion of iron stores. Also called microcytic hypochromic anemia.
Symptoms include fatigue, weakness, headaches, apathy, pallor and poor resistance to cold temperatures.
Iron Deficiency and Behavior
Energy metabolism is impaired.
Neurotransmitter synthesis is reduced.
Physical work capacity is reduced.
Mental productivity is reduced.
Iron Deficiency and Pica
Habit of eating ice, clay, paste, and other nonfood substances
Generally in women and children from low-income groups
D. Iron Toxicity
Iron Overload
Hemochromatosis is generally a genetic disorder that enhances iron absorption.
Repeated blood transfusions
Massive doses of supplemental iron
May cause hemosiderosis
Symptoms include apathy, lethargy, and fatigue
Problems include liver tissue damage and infections
Higher risk of diabetes, liver cancer, heart disease, and arthritis
Iron and Heart Disease – may be a link to high iron stores
Iron and Cancer – may be a link with free radical activity
Iron Poisoning
Upper level for adults: 45 mg/day
Accidental supplement poisoning in children
Symptoms include nausea, vomiting, diarrhea, constipation, rapid heartbeat, weak pulse, dizziness, shock, and confusion
E. Iron Recommendations and Sources
Recommended 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 needs 1.8 times as much iron because of low bioavailability.
Iron in Foods
Red meats, fish, poultry, and shellfish
Eggs
Legumes
Dried fruits
Iron-Enriched Foods
Often added to grain foods
Not absorbed as well
Maximizing Iron Absorption
Bioavailability is high in meats, fish, and poultry.
Bioavailability is medium in grains and legumes.
Bioavailability is low in vegetables.
Combined effect of enhancing and inhibiting factors
Iron Contamination and Supplementation
Contamination Iron
Iron cookware takes up iron salts
Acidic foods and long time cooking 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.
A. 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 damaging free radicals
Affects platelets in blood clotting and wound healing
Affects thyroid hormone function
Influences behavior and learning performance
Taste perception
Sperm development
Fetal development
B. Zinc Absorption and Metabolism
Zinc Absorption
Rate of absorption depends on zinc status
Phytates and fiber bind zinc and reduce absorption.
Metallothionein is a special protein that holds zinc in storage.
Zinc Recycling
Enteropancreatic circulation
Losses occur in the feces.
Zinc Transport
Transported by the protein albumin
Binds to transferrin
C. 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
Loss of appetite
D. Zinc Toxicity
Upper Level for Adults: 40 mg/day
Symptoms
Loss of appetite
Impaired immunity
Low HDL
Copper and iron deficiencies
Vomiting and diarrhea
Exhaustion
Headaches
E. Zinc Recommendations and Sources
Recommended Intakes (2001 RDA)
RDA Men: 11 mg/day
RDA Women: 8 mg/day
Zinc in Foods
Red meats and shellfish
Whole grains
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 eliminated iodine deficiency in the United States and Canada.
Iodide Roles in the Body
Component of two thyroid hormones
Regulates growth, development, and metabolic rate
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.
Cretinism is a congenital disease characterized by mental and physical retardation and commonly caused by maternal iodine deficiency during pregnancy.
Goitrogen overconsumption– naturally occurring in cabbage, kale, brussels sprouts, cauliflower, broccoli, and kohlrabi
Iodine Toxicity
Upper level 1000 g/day
Symptoms include underactive thyroid gland, elevated TSH, and goiter
Supplement use, medications, and excessive iodine from foods
Iodine Recommendations and Sources
Recommendations (2001 RDA) Adults: 150 g/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 Deficiency
Keshan disease – a pre-disposition to heart disease where cardiac tissue becomes fibrous
Prevalent in regions of China
Selenium and Cancer
May protect against certain forms of cancer
Inconclusive evidence and more research is needed
Food sources are better than supplements
Selenium Recommendations and Sources
Recommendations (2000 RDA) Adults: 55 g/day
Sources include seafood, meat, whole grains, and vegetables (depends on soil content)
Selenium Toxicity
Upper Level for Adults: 400 g/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 Roles in the Body
Absorption and use of iron in the formation of hemoglobin
Part of several enzymes
Some copper containing enzymes are antioxidants.
Copper Deficiency and Toxicity
Deficiency symptoms include anemia and bone abnormalities.
Menkes disease
Toxicity
Upper Level for Adults: 10,000 g/day (10 mg/day)
Wilson’s disease
Copper Recommendations and Sources
Recommendations (2001 RDA) Adults: 900 g/day
Sources
Seafood, nuts, seeds and legumes
Whole grains
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 widespread in foods.
Manganese Roles in the Body
Cofactor for several enzymes
Assists in bone formation
Pyruvate conversion
Manganese Deficiency and Toxicity
Deficiency symptoms are rare
Phytates, calcium and iron limit absorption.
Toxicity occurs with environmental contamination.
Upper Level for Adults: 11 mg/day
Toxicity symptoms include nervous system disorders.
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 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
B. Fluoride and Dental Caries
Widespread health problem
Leads to nutritional problems
C. Fluoride and Toxicity
Tooth damage called fluorosis
Upper Level 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 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 enhances insulin’s action. It is widely available in unrefined foods.
Chromium Roles in the Body
Enhances insulin action
Glucose tolerance factors (GTF) are small organic compounds that enhance insulin’s action
Chromium Recommendations and Sources
Recommendations (2001 AI)
AI Men: 35 g/day
AI Women: 25 g/day
Sources
Meat, especially liver
Whole grains
Brewer’s yeast
Chromium Supplements
Do not effectively improve glucose or insulin response in diabetics
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
Recommendations (2001 RDA)
Adults: 45 g/day
Upper Level 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.
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.
A. 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
Highlight: 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.
A. The Phytochemicals
Defending against Cancer
Phytoestrogens mimic estrogen
Antioxidant activity
Slow the growth of breast and prostrate cancer
Found in soybeans, flaxseed oil, whole grains, fruits and vegetables
Lycopene
Powerful antioxidant
Inhibit 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.
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
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 in Perspective
Difficult to assess one food and its benefits alone
Actions of phytochemicals are complementary and overlapping
B. Functional Foods
Foods as Pharmacy
Yogurt and probiotics
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.
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?
Future Foods
Use of gene research
Can we design foods to meet exact health needs of each individual?
3. Can farmers grow the “perfect” foods?