Trace Minerals

1. Trace Minerals Chapter 15

2. Learning Outcomes • Describe the important food sources, major functions, deficiency and toxicities of each trace mineral discussed in class • Understand trace mineral absorption, transportation, storage and excretion.

3. Overview of trace minerals • Inorganic substances needed by the body in small quantities • Includes iron, zinc, copper, maganese, iodine, selenium, chromium, fluoride, and molybdenum • Typically difficult to measure in the body and in food

4. Iron • Foods • Heme iron: iron part of hemoglobin and myoglobin in animal flesh • Nonheme iron: vegetables, grains, and supplements • Needs • RDA 18 mg/day adult women, 8 mg/day adult men • After menopause drops to 8 mg/day • Most common trace mineral deficiency worldwide

5. Iron • Absorption, Transportation and Excretion • Ferritin: iron binding protein in small intestine • Storage form of iron, made in response to iron stores • Also acts as “mucosal block” • Transferrin: protein that binds iron and transports it through body (needs copper) • Absorption and storage is tightly regulated in the body because the body has limited ability to excrete absorbed iron • Most iron is recycled, only 10% is excreted

6. Non heme must be in Fe2+ form to be absorbed Mucosal “block” Muscle (Myogl) Bone marrow RBC (Hgb) Liver

8. Iron • Functions • Component of proteins • Hemoglobin-protein in red blood cells that carries oxygen in body • Myoglobin- protein in muscle that carries oxygen to muscles and heart

9. Iron • Functions • Component of enzymes or act as coenzyme • Needed for energy metabolism • Needed for drug and alcohol metabolism in the liver • Needed for neurotransmitter synthesis • Needed for immune system

10. Iron Deficiency • Iron deficiency anemia • At risk: premature infants, children, females of child bearing age, vegetarians

12. Iron deficiency • Pale skin, fatigue and weakness. • In severe cases, trouble breathing • Pica for ice is a very specific symptom • Lightheadedness

13. Iron • UL • 45 mg/day • Nausea, vomiting, diarrhea, constipation, interfere with absorption of other minerals • Who? • Supplements (especially kids) • Hemochromatosis- genetic disorder that can cause liver disease and heart failure • Frequent blood transfusions

14. Case Study Betsy just got diagnosed with iron deficiency anemia. What would be a good breakfast? • Iron fortified cereal with milk and coffee • Spinach and cheese omelet • Steak and eggs • Ham, egg, and cheese on whole grain bread with OJ

15. Zinc • Foods • Protein rich meat and seafood, whole grains • Needs • RDA 8-11 mg, most in US get adequate zinc • Absorption, Transportation and Excretion • Has a mucosal block similar to iron (metallothionein) • Not stored, but is recycled • Can be excreted in feces, so less toxic than iron

16. Zn Absorption

17. Zinc • Function • At least 300 different enzymes require zinc • DNA synthesis, immune function, growth and development, home synthesis, antioxidant • Deficiency • Overt deficiency common in poverty • Low appetite, impaired growth, decreased taste, immune dysfunction • North America-marginal deficiencies if absorptive diseases, dialysis, vegetarians

18. Zinc • UL • 40 mg/day-usually people who take supplements • Low appetite, nausea, vomiting, GI upset

19. Copper • Foods • Liver, shellfish, nuts, seeds, mushrooms, soy and dark chocolate • Needs • RDA 900 micrograms daily • Deficiency rare • Absorption, Transportation and Excretion • Little is stored, excreted in feces • Binds to metallothione in intestine • Copper balance controlled by copper absorption and influenced by iron and zinc status

20. Copper • Function • Iron metabolism • In family of enzymes that act as antioxidants • Deficiency rare • Menkes disease • UL • Toxicity is also rare • Wilson’s disease

21. Is chocolate good for you? • One study reported that men who ate the most chocolate had a 47 percent lower mortality rate over 15 years than a similar group that consumed little chocolate. • Another study that showed a small amount of chocolate slowed platelet clumping. • A new chocolate called CocoaVia got a lift from the Journal of the American Dietetic Association, which reported that two (small) bars a day lowered LDL cholesterol in a high-cholesterol subject group by 6.7 percent

22. Match the deficiency with the anemia • Vitamin E • Folate • Vitamin B12 • Iron • Copper • Megaloblastic • Microcytic • Hemolytic *** See page 548 in book for summary

23. Manganese • Foods • Whole-grain cereals, nuts, legumes and tea • Needs • AI 1.8-2.3 mg/daily • Deficiency rare • Absorbed in small intestine, transported with protein carriers, excreted in bile • Only ~10% is absorbed, unless need is high • Absorbed better if iron status is good

24. Manganese • Function • Shares functional similarities with Zinc and Copper (cofactor for enzymes, energy metabolism) • Deficiency • Rare • UL • 11 mg/day • Inhalation of car emissions • Causes nerve damage

25. Iodine • Foods • Saltwater seafood, seaweed, iodized salt, molasses and dairy products • Needs • RDA is 150 micrograms daily • ½ teaspoon of iodized salt meets RDA requirement • Absorbed efficiently and stored in thyroid gland, excreted in urine

26. Iodine • Function • Component of thyroid hormone so needed for normal metabolism • Deficiency • Goiter (enlarged thyroid) and cretinism (poor growth)

28. Iodine • UL • 110 micrograms/day • Enlarged thyroid gland, increased risk of thyroid cancer • Japan- high intake of seaweed • Chile- high levels in soil

29. Selenium • Foods • Seafood, meats, cereal grains and nuts • Soil dependent • Needs • RDA 55 micrograms adults • Intake typically above the RDA • Easily absorbed, excess is excreted in urine

30. Selenium • Function • Anti-oxidant defense network (similar to vitamin E, protects cell membranes from oxidation) • Synthesis of thyroid hormone • May decrease risk of cancer (especially prostrate and lung) • Deficiency • No specific disease but deficiency can cause Keshan disease • UL • 400 micrograms daily • Nausea, diarrhea, fatigue, hair loss, change in nails, and skin rashes

31. Selenium and Cancer • 1) Epidemiology studies show that where selenium levels in the soil are high, death rates from cancer are significantly lower. • 2) Clinical trial studies • 32,000 men • Researchers gave the men either selenium, vitamin E, or a combination of selenium and vitamin E to learn whether either would lower the risk of prostate cancer. • This study was suspended early because analysis found no benefit to taking selenium for an average of more than 5 years.

32. Chromium • Foods • Nutrient databases inadequate • In many foods including broccoli, processed meats, liver, eggs, whole grain products • Needs • AI 25-35 micrograms • Uncommon deficiency and no UL • Functions • May improve insulin function and help normalize blood sugar, although supplements have not been shown to be beneficial

33. Fluoride • Foods • Fluoridated water, tea, seafood and seaweed • Non food sources are toothpaste and mouthwash • Needs • AI 3-4 mg/daily • Easily absorbed and stored in teeth and bones • Function • Promotes bone and dental health

35. Fluoride • Deficiency • Associated with an increase in dental caries • UL • .1 mg/kg body weight daily up to 8 years old • Most risk is 8 yo or younger • Mottling or fluorosis with chronic intake

36. Myths • I drink bottled water, am I missing out on the benefits of Fluoride? • Do I need to drink fluoridated water if I brush my teeth? • What are other health effects of too much fluoride?

37. Ultra trace Minerals Needed in very small amounts but essential for many enzymes • Molybdenum • Boron • Nickel • Silicon • Arsenic • Vanadium