Trace Minerals

1. Trace Minerals

2. The Trace Minerals--An Overview • Trace minerals are needed in very small (trace) 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.

3. The Trace Minerals--An Overview • Food Sources • Depends on soil and water composition • Depends on processing • Bioavailability • Wide variety of unprocessed foods

4. The Trace Minerals--An 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.

5. The Trace Minerals--An 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

6. 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.

7. Iron Roles in the Body • 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

8. 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

9. Iron in food If the body does not need iron Iron is not absorbed and is excreted in shed intestinal cells instead. Thus, iron absorption is reduced when the body does not need iron. Mucosal cells in the intestine store excess iron in mucosal ferritin (a storage protein). If the body needs iron Mucosal ferritin releases iron to mucosal transferrin (a transport protein), which hands off iron to another transferrin that travels through the blood to the rest of the body. Stepped Art Fig. 13-1, p. 443

10. Iron Absorption and Metabolism • 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%

11. Only foods derived from animal flesh provide heme, but they also contain nonheme iron. Heme accounts for about 10% of the average daily iron intake, but it is well absorbed (about 25%). Key: Heme Nonheme iron accounts for the remaining 90%, but it is less well absorbed (about 17%). Nonheme All of the iron in foods derived from plants is nonheme iron. Stepped Art Fig. 13-2, p. 444

12. Iron Absorption and Metabolism • Absorption-Enhancing Factors • MFP factor • 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.

13. Iron Absorption and Metabolism • 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

14. Iron Absorption and Metabolism • Individual Variation • Dietary factors • Health status • Stage in life cycle • Iron status

15. Iron Absorption and Metabolism • 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.

16. Iron Absorption and Metabolism • 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.

17. Some losses via sweat, skin, and urine Transferrin carries iron in blood. Some iron delivered to myoglobin of muscle cells Liver (and spleen) dismantles red blood cells, packages iron into transferrin, and stores excess iron in ferritin (and hemosiderin). Bone marrow incorporates iron into hemoglobin of red blood cells and stores excess iron in ferritin (and hemosiderin). Iron-containing hemoglobin in red blood cells carries oxygen. Some losses if bleeding occurs Stepped Art Fig. 13-3, p. 445

18. Iron Deficiency • 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

20. 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

21. 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.

22. 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.

23. 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.

24. Iron • Iron Toxicity • Iron Overload • Hemochromatosis is generally a genetic disorder that enhances iron absorption. • Iron overload can also be caused by: • Repeated blood transfusions • Massive doses of supplemental iron • Rare metabolic disorders

25. 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

26. 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

27. 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.

28. Iron • Iron Recommendations and Sources • 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

30. Iron • Iron Recommendations and Sources • 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

31. 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

32. 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.

33. 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

34. 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

35. 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.

36. Zinc • Zinc Absorption and Metabolism • 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.

37. Zinc in food If the body does not need zinc Zinc is not absorbed and is excreted in shed intestinal cells instead. Thus, zinc absorption is reduced when the body does not need zinc. Mucosal cells in the intestine store excess zinc in metallothionein. The pancreas uses zinc to make digestive enzymes and secretes them into the intestine. If the body needs zinc Metallothionein releases zinc to albumin and transferrin for transport to the rest of the body. Stepped Art Fig. 13-6, p. 453

38. Zinc • Zinc Absorption and Metabolism • 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.

39. 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

41. 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

42. 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.

44. 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.

45. 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.

46. 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 duringpregnancy.

48. Iodine • Iodine Toxicity • UL 1100 μg/day • Symptoms include underactive thyroid gland, elevated TSH, and goiter. • Supplement use, medications, and excessive iodine from foods

49. 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

50. 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