Chapter 13THE TRACE MINERALS

Food sources Depend on soil and water composition Depend on food processing

Deficiencies Can affect people of all ages May be difficult to recognize

Toxicities FDA regulation of supplements

THE TRACE MINERALS – AN OVERVIEW

Interactions Common and well coordinated to meet needs May lead to nutrient imbalances

Excess in one may cause a deficiency of another Interfere with work of minerals Contaminant minerals causing toxic reactions

Research of trace minerals is active, suggesting there is more to learn.

THE TRACE MINERALS – AN OVERVIEW

Too little and too much can be harmfulRoles in the body

Switches back and forth between two forms Ferrous iron (reduced state) Ferric iron(oxidized state)

Cofactor in oxidation-reduction reactions Widespread in metab; enzymes making aa, collagen, hormones, &

neurotransmitters Part of electron carriers

Form water & produce ATP Hemoglobin and myoglobin

2 proteins found in RBC & muscle cells

IRON

Absorption Body conserves iron

Balance maintained primarily through absorption Ferritin

Iron-storage in small intestine When Fe is needed ferritin releases some Fe to an Fe support

protein called Transferrin

Iron transport protein

IRON (FE)

IRON ABSORPTION

Absorption Dietary sources

Heme iron (animals) Nonheme iron (plant & animal)

Absorption-enhancing factors MFP factor

Peptide that promotes absorption of nonheme Fe from other foods eaten at same meal

Vitamin C Some acids and sugars

IRON

HEME AND NONHEME IRON IN FOODS

Absorption-inhibiting factors Phytates Vegetable proteins Calcium Polyphenols

Dietary factors combined; MFP & vit C as enhancers & phytates as inhibitors

Individual variation in absorption Health, stage in life cycle, and 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 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 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

Deficiency Most common nutrient deficiency worldwide Populations affected in U.S.

10% toddlers, adolescent girls, and women of childbearing age Link with being overweight Vulnerable stages in life

Women in reproductive years Pregnancy Infants and young children Adolescence

IRON

Deficiency Blood losses

Assessment of deficiency Deficiency develops in stages

Iron stores diminish – serum ferritin Decrease in transport iron – transferrin Iron deficiency – hemoglobin and hematocrit values

IRON

Iron deficiency and anemia Deficiency – depleted iron stores without regard to degree of

depletion Anemia – severe depletion of iron stores

Low hemoglobin concentrations Pale & small RBCs (hypochromic, microcytic)

IRON

Deficiency and behavior Energy metabolism is impaired Neurotransmitter synthesis is altered

Reduces work capacity and mental productivity Motivational problems

Pica Craving and consumption of nonfood substances

IRON

Toxicity Hereditary hemochromatosis

(Most common genetic disorder in U.S.) Genetic failure to prevent unneeded iron in the diet from being

absorbed Hormone hepicidin supports homeostasis and

absence/ineffectiveness causes hemochromatosis Hemosiderosis

Deposits of iron-storage pro hemosiderin in liver, heart, joints, and other tissues

IRON

Symptoms of iron overload include: infections, fatigue, joint pain, skin pigmentation, and organ

damage. Problems include liver tissue damage and infections. Higher risk of diabetes, liver cancer, heart disease, and arthritis. More common in men then in women.

Treated with chelation therapy Use of EDTA to bind with metallic ions, thus healing the body by

removing toxic metals

IRON

Heart disease Excess iron

Free radicals

Cancer Free-radical damage

Iron poisoning Symptoms of toxicity UL

IRON

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, rapid heartbeat, weak

pulse, dizziness, shock, and confusion.

IRON

Recommendations and sources Select iron-rich foods

Natural – meats, fish, poultry, legumes, eggs Enriched – flour and grain products

RDAs 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.

Maximizing absorption Bioavailability is

high in meats, fish, and poultry. intermediate in grains and legumes. low in vegetables.

Combined effect of enhancing and inhibiting factors.

IRON

Contamination & supplementation Iron cookware

Iron content of foods Supplements

Groups that may need supplements Enhancing absorption Vitamin C Physician prescription

IRON

Roles in body Gene expression Cell membranes Immune function Growth & development Synthesis, storage, and release of insulin Blood clotting Thyroid hormone function Behavior & learning performance Visual pigment Taste perception Sperm production

Zn def impairs all these and other functions, underlining the vast importance of Zn in supporting the body’s proteins.

ZINC

Absorption Rate varies depending on zinc status Dietary factors

Upon absorption Zn can participate in metabolic function of intestinal cells itself or may be retained

with the intestinal cells by metallothionein until the body needs Zn Recycling

Small intestine Two doses of zinc (food/meals & Zn-rich pancreatic secretions) Enteropancreatic circulation

travels from the pancreas to the intestines and back. Zinc losses

occur in the feces, urine, shedding of skin, hair, sweat, menstrual fluids, and semen.

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 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 ToxicityUL for Adults: 40 mg/day.Symptoms

Loss of appetite. Impaired immunity.Low HDL.Copper and iron deficiencies.Vomiting and diarrhea.Exhaustion.Headaches.

Zinc Recommendations and SourcesRDA Men: 11 mg/day.RDA Women: 8 mg/day.

ZINC

Zinc in foodsProtein-containing foods such as shellfish, meats, poultry, milk, and cheese.

Whole grains, legumes, and some fortified cereals.

Zinc SupplementationDeveloping countries use zinc to reduce incidence of death associated with diarrhea.

Zinc lozenges for the common cold are controversial and inconclusive.

ZINC

GI tract converts iodine to iodide Iodine – in food Iodide – in body

Roles in the body Part of thyroid hormones

Body temperature, metabolic rate, reproduction, growth, blood cell production, nerve and muscle function, etc.

IODINE

Deficiency Thyroid hormone production declines

Greater secretion of thyroid-stimulating hormone (TSH) Goiter

Enlarged thyroid

Most common cause of preventable mental retardation and brain damage Cretinism-severe def during pregnancy; irreversible

IODINE

Toxicity Interferes with thyroid function

Enlarges thyroid gland Goiter in an infant UL

Adult: 1100 micrograms/day

Recommendations Sources

IODINE

Substitute for sulfur in some amino acids Methionine, cysteine, and cystine

Roles in body Antioxidant Part of proteins

Glutathione peroxidase; works with vit E Prevents free-rad formation

Conversion of thyroid hormone to active form

SELENIUM

Deficiency Heart disease

Cancer May be protective factor

Foods vs. supplements

Toxicity UL: 400micrograms/day Effects

SELENIUM

Sources Found in soil Meats, milk, and eggs Brazil nuts

Recommendations RDA: 55µg/day

SELENIUM

Transport and balance depend on a system of proteinsRoles in body

Constituent of enzymes Reactions that consume oxygen or oxygen radicals

Iron metabolism Defense against oxidative damage Other roles

COPPER

Deficiency Deficiency is rare in the U.S.; however, symptoms include anemia and bone abnormalities. In Menkes disease, copper cannot be released into the circulation.

Recommendations – Adults: 900 g/day. Sources

Seafood, nuts, seeds, and legumes. Whole grains. In houses with copper plumbing, water can be a source.

Toxicity Excessive intakes

Foods vs. supplements Genetic disorders

Menkes disease Wilson’s disease

Major route of elimination appears to be bile

COPPER

Body locations Bones Metabolically active organs

Roles in body Cofactor for enzymes that facilitate metabolism Bone formation Conversion of pyruvate to a TCA cycle compound

MANGANESE

Deficiency Deficiency symptoms are rare. Phytates, calcium, and iron limit absorption.

Toxicity Toxicity occurs with environmental contamination. UL for Adults: 11 mg/day. Toxicity symptoms include nervous system disorders.

Manganese Recommendations and Sources Recommendations

AI Men: 2.3 mg/day. AI Women: 1.8 mg/day.

Sources include nuts, whole grains, leafy vegetables, and tea.

MANGANESE

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.

Toxicity Tooth damage called fluorosis – irreversible pitting and discoloration of the

teeth. UL for Adults: 10 mg/day.

FLUORIDE

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.

Recommendations AI Men: 4 mg/day. AI Women: 3 mg/day.

Sources include fluoridated drinking water, seafood, and tea.

FLUORIDE

Roles in the body Participates in carbohydrate and lipid metabolism Helps maintain glucose homeostasis

Diabetes-like condition

Sources Refined foods

Supplements

CHROMIUM

Roles in the Body Enhances insulin action and may improve glucose tolerance. 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.Recommendations

AI Men: 35 g/day. AI Women: 25 g/day.

Sources include meat (especially liver), whole grains, and Brewer’s yeast.

Supplements Claims about reducing body fat and improving muscle strength

remain controversial.

CHROMIUM

Look at nutrients as a whole Work cooperatively with one another

Actions are most often interactions Most foods deliver multiple nutrients

Needs are based on the support of optimal healthNutrients are being examined in context of whole diet

CLOSING THOUGHTS ON THE NUTRIENTS