Chapter 14: Trace Minerals Objectives Describe the major functions of copper, fluoride, iodine, iron, selenium, and zinc in the body Identify the general properties of trace minerals Describe how the use of iodine and the production of thyroid hormone are controlled Describe the symptoms of deficiency and toxicity of copper, fluoride, iodine, iron, selenium, and zinc Identify at least two dietary sources of copper, iodine, iron, selenium, and zinc Discuss the dietary sources of heme and non-heme iron and the factors that affect their absorption

The Goiter Belt During World War I, 64.4% of people in Michigan showed signs of a goiter Soils deficient in iodine Added iodine to table salt Iodine deficiency remains one of the most important public health issues globally In World War I many men, women, and children of the Goiter Belt (as many as 64.4% of people in some parts of Michigan) were showing signs of a goiter, an enlargement of the thyroid gland. Many military recruits were too unhealthy to serve in the war efforts. The soils of the Great Lakes, Appalachians, and Northwestern regions of the United States are poor in the trace mineral iodine, which the body needs to make thyroid hormones.

Trace Minerals Micro-minerals are iodine, iron, zinc, copper, selenium, molybdenum, fluoride, manganese, and chromium Need significantly less than major minerals Daily requirement <100 mg/day Critical for health

Properties of Trace Minerals Bioavailability influenced by Form of the food Nutrition status Age Pregnancy Safe range of intake narrow Intake above the UL through supplements It’s rare to overconsume minerals through food alone, but using supplements can result in intakes above the UL and potentially dangerous adverse effects. Eating a balanced and varied diet can provide enough trace minerals.

Properties of Trace Minerals

Iodine (I) Foods depend upon iodine content of the soil U.S. salt company began to add iodine to salt 15% of U.S. salt intake iodized Sources of iodine Seafood Milk Processed grains

Iodine Functions Component of thyroid hormone Regulates energy metabolism and protein synthesis Critical role in the development of the fetal skeleton and brain Thyroid-stimulating hormone (TSH) Secreted from the pituitary gland Regulates the thyroid

Iodine Functions

Iodine Deficiency Hypothyroidism Cretinism Slow metabolic rate Goiter Mental retardation, deafness, stunted growth, and other abnormalities Mild forms of iodine deficiency in pregnancy can affect neurological development

Iodine Recommended Intakes RDA for >19 years of age: 150 mcg

Iodine Excessive Intake UL = 1,100 mcg Excessive intake can cause : goiter, hypothyroidism, and elevated TSH

Iron (Fe) Types Heme iron Non-heme iron Most abundant trace mineral Hemoglobin Myoglobin Non-heme iron Most abundant trace mineral Component of many enzymes Important in reproduction, growth, and healing The World Health Organization considers iron deficiency to be the number one nutritional disorder in the world, affecting as much as 80% of the world’s population in both developing and industrialized nations.

Iron in the Body The World Health Organization considers iron deficiency to be the number one nutritional disorder in the world, affecting as much as 80% of the world’s population in both developing and industrialized nations.

Iron in the Body The World Health Organization considers iron deficiency to be the number one nutritional disorder in the world, affecting as much as 80% of the world’s population in both developing and industrialized nations.

Iron Sources Food sources Absorption Heme in red meats, poultry, and fish Non-heme in plant foods Lentils, beans, dried fruits, and grain products Absorption Increased by vitamin C, acid, and meat Decreased by soy protein, phytates, and polyphenols, as well as calcium intake Iron balance in the body is regulated by iron absorption, storage, release, and transport.

Iron Deficiency Iron deficiency anemia Symptoms Caused by blood loss Insufficient iron intake High-risk groups Children, pregnant, and menstruating women Symptoms Tired, out of breath, poor performance, and slow cognitive and social development

Iron Recommendations RDA for men >19 years of age = 8 mg RDA for women 19 to 50 years of age = 18 mg Assumes 75% heme iron RDA for vegetarians doubled (non-heme iron) Athletes have a 30% higher requirement

Iron Recommendations

Iron Recommendations UL for men and women >19 years of age = 45 mg Cause gastrointestinal distress Diarrhea, constipation, nausea, vomiting Iron toxicity causes apathy, fatigue, liver damage, and immune problems Iron poisoning Unintentional death in children Nausea, vomiting, diarrhea, rapid heartbeat, dizziness, shock, and confusion

Zinc (Zn) Dr. Prasad Diets heavy in bread and grains High in phytates that bind iron and zinc Growth retardation and delayed sexual maturation

Zinc (Zn) Cofactor for over 900 enzymes Required for almost every essential process in the body Regulation of protein synthesis Reproduction Cell division Growth and development Immune responses Neurological functions

Zinc Deficiency Symptoms At-risk groups Impaired immune function Appetite loss and weight loss Delayed sexual maturation Stunted growth Severe deficiency can result in hair loss, diarrhea, infertility in males, and impaired neurological and behavioral function At-risk groups Alcoholics Vegetarians Elderly Alcohol decreases absorption and increases excretion Phytates inhibit absorption About 13% of the U.S. population is at risk for zinc deficiency.

Zinc Recommendations RDA for males >19 years of age = 11 mg RDA for females >19 years of age = 8 mg Vegetarians’ needs are doubled UL = 40 mg Excessive intake can lead to nausea, vomiting, diarrhea, copper deficiency, reduced immune function, and altered iron function

Zinc Sources

Zinc Sources

Copper (Cu) Functions Cofactor in oxygen-dependent enzymes Energy metabolism Formation of connective tissues Regulation of iron storage and transport Antioxidant functions May slow progression of age-related macular degeneration

Copper Deficiency Rare in the United States Mostly secondary to other factors Malabsorption from other conditions Gastric bypass surgery Excessive zinc intake Symptoms Anemia Impaired immune response Osteoporosis

Copper Recommendations RDA = 900 mcg/day

Selenium (Se) Functions Cofactor of several antioxidant enzymes Activation of thyroid hormone Essential for normal growth, development, and metabolism

Selenium Deficiency Deficiency Low selenium status increases risk for a particular form of heart disease May increase risk of some cancers Decreases immune function

Selenium Recommendations RDA for adults = 55 mcg UL = 400 mcg Hair and nail brittleness and loss Single high dose fatal Food sources Meats and cereals Plant food sources vary due to soil concentrations Brazil nuts Absorption not regulated

Other Trace Minerals Chromium (Cr) Fluoride Manganese Molybdenum Enhances the action of insulin Fluoride Hardens the enamel of our teeth Prevents of dental caries Manganese Cofactor for enzymes in antioxidant function, energy metabolism, bone development, and neurotransmitter production Molybdenum Cofactor for four enzymes in metabolism

Ultratrace Minerals Intake requirements <1 mcg/day Food only safe source of intake Specific biological or physiological functions not yet identified Not currently classified as essential Animal data suggest these may be important Arsenic (As) Boron (B) Nickel (N) Silicon (Si) Vanadium (V)

Summary Trace minerals are essential nutrients required in very small amounts in human nutrition and include chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, and zinc Trace minerals have vital roles in the body, such as participating as cofactors in numerous chemical reactions Found in both plant and animal foods, the actual bioavailability of trace minerals is influenced by many factors Trace mineral deficiencies can have varied, yet serious, consequences particularly of concern in pregnant woman and growing children

Summary (Cont’d) Trace minerals are found across all food groups; thus, sufficient intake can generally be achieved by consuming a varied and balanced diet Ultratrace minerals are not currently classified as essential nutrients but may have important values in the body; they are arsenic, boron, nickel, silicon, and vanadium