Minerals

1. Minerals Lecture 7

2. What are minerals? • Small, naturally occurring, inorganic, chemical elements • Regulate body processes • Give structure to things in the body • No calories (energy) • Cannot be destroyed by heat

3. Categories of minerals • Trace minerals • Chromium • Copper • Flouride • Iodine • Iron • Manganese • Selenium • Zinc • microminerals • Major minerals • Calcium • Phosphorus • Magnesium • Electrolytes (sodium, chloride, potassium) • sulfur • macrominerals are essential at levels of 100mg or more per day for human adults

4. The electrolytes • There are 3 major electrolytes: • sodium • potassium • chloride

5. Sodium (Na) • deficiency: • dehydration • acidosis • tissue atrophy • excess: • edema • hypertension • Sodium is the principal cation in extracellular fluids • functions include: • osmotic equilibrium (fluid balance) • acid-base balance • carbon dioxide transport • cell membrane permeability • muscle irritability • food sources: table salt, salty foods (potato chips, pretzels, etc.), baking soda, milk. • RDA for adults: 1.1 to 3.3 gm/day

6. Potassium (K) • The principal cation in intracellular fluid • functions: • buffer constituent • acid-base balance • water balance • membrane transport • neuromuscular irritability • deficiency (hypokalemia) • causes: • increased renal excretion (diuretics) • primary aldosteronism • severe vomiting and diarrhea • cutaneous losses via perspiration • excess(hyperkalemia) • causes: • sudden increased intake • severe tissue trauma and burns, acute and chronic acidosis • Food sources: vegetables, fruit (bananas), whole grains, meat, milk; RDA for adults: 1.5 - 4.5 gm/day

7. Chloride (Cl) • an essential anion • closely connected with sodium in foods, body tissues and fluids and excretions • readily absorbed along with sodium • important for osmotic balance, acid-base balance and in the formation of gastric HCl • Deficiency of chloride: • hypochloremic alkalosis • hypovolemia • pernicious vomiting • psychomotor disturbances

8. Calcium (Ca) • the most abundant of the minerals • the 5th most abundant element in the body • needed by all cells • found in largest amounts in bones (90%) • controlled by parathyroid hormone (PTH), calcitonin and vitamin D • about 1/2 is in the ionized form in serum • the other 1/2 forms calcium citrate complex

9. Calcium • function of calcium: • structural unit of bones and teeth • contraction and relaxation of muscles • stabilizes nervous tissue • low calcium --- irritable nerves --- tetany • high calcium --- depresses the nervous irritability • required for blood clotting • activates various enzymes (glycogen phosphorylasekinase, salivary and pancreatic amylase) • RDA • adult: 800 mg/day • pregnacy and lactation: 1200 mg/day

10. Phosphorus • Phosphorus is the second most abundant mineral in the body • required in many phases of metabolism • foods rich in calcium are also richest in phosphorus (milk, cheese, eggs, beans, fish) • RDA for phosphorus is established on the basis of a 1:1 relationship with calcium • Adults: 700 mg/day • Pregnancy and lactation: • Younger than 18: 1250 mg/day • Older than 18: 700mg/day • Generates energy • Regulate energy metabolism • Component of bones, teeth • Part of DNA, RNA (cell growth, repair)

11. Magnesium • second most plentiful cation in intracellular fluids • ~50% of total amount in bone • ~45% in muscle and nervous tissue • ~ 5% in extracellular fluids • Part of 300 enzymes (regulates body functions) • Maintains cells in nerves, muscles • Component of bones • Best sources are all green plants (chlorophyll); meats • RDA: 350 mg/day • pregnancy and lactation: 450 mg

12. Copper (Cu) • Deficiency • decreased iron absorption • neutropenia • bone demineralization • failure of erythropoiesis • sources • liver, shellfish, whole grains, cherries, legumes, nuts • important trace mineral • component of several enzymes • needed to form hemoglobin and collagen

13. Fluorine • Considered essential because of its beneficial effect on tooth enamel • Benefits include: less dental caries, stronger bones, reduction in osteoporosis • In large quantities it is deleterious to teeth; dental fluorosis: chalky, dull white patches and mottling of teeth • 1 to 2 parts per million is adequate for drinking water • Main sources include drinking water and plants (spinach, lettuce, onions) • Average daily intake: 1.5 – 4.0 mg/day

14. Iodine • iodine is necessary for the formation of thyroid hormones (T-4 thyroxine and T-3 triiodothyronine) • deficiency of iodine is manifested by a goiter (enlargement of the thyroid gland) • salt water fish and seaweeds are a good source of iodine • to prevent the development of endemic goiter, table salt has been spiked with sodium iodide

15. Chromium • Cr III may act as a cofactor for insulin, enhancing glucose utilization • deficiency leads to impaired glucose tolerance (glucose tolerance factor) • chromium may have a role in type 2 diabetes • sources: corn oil, whole-grain cereals, drinking water (variable) • RDA: 0.05 – 0.2 mg • frequently available in pharmacies as chromium picolinate

16. Manganese • Deficiency leads to: • Weight loss • Transient dermatitis • Nausea and vomiting • Changes in hair color • Sources: blueberries, wheat bran, beet greens, lettuce, legumes, fruit • RDA: 2.5 – 5.0 mg • Maganese is an activator of several different enzymes: • Phosphoglucomutase • Isocitricdehydrogenase • Cholinesterase • Intestinal peptidase • Carboxylases • ATPases • However, magnesium and cobalt can replace Mn in several enzymes

17. Iron (Fe) • Types of body iron (Dietary Iron) • Heme iron (animal source) • hemoglobin, myoglobin, catalases, peroxidases, cytochromes (a, b and c – involved in electron transport), cytochrome P450 (involved in drug metabolism) , • Non-heme iron (vegetables/cereals) Ferritin, transferrin • Enzymes—methane monooxygenase (oxidizes methane to methanol), • Ribonucleotide reductase (reduces ribose to deoxyribose; DNA biosynthesis)

18. Food Iron non-heme iron • vegetables • fruits • legumes • nuts • breads and cereals only ~ 3 of non heme iron is absorbed heme iron • meats • poultry • fish 20-23% of heme-iron is absorbable

19. Iron absorption • average diet contains 10 - 15 mg of iron per day • a normal person absorbs 5 -10% of this iron or 0.5 - 1.0 mg daily • occurs in upper part of small intestine • also requires copper • ferrous is better absorbed than ferric form • iron absorption increases in response to low iron stores • pregnant women: 3 - 4 mg per day

20. Iron distribution and storage • stored in 2 forms: • ferritin (a water soluble complex consisting of a core of ferric hydroxide and a protein shell (apoferritin) • hemosiderin (a particulate substance consisting of aggregates of ferric core crystals) • stored in liver, spleen, bone marrow, intestinal mucosal cells and plasma

21. IRON DEFICIENCY Causes: • excessive blood loss (parasitic, accidental): is most common cause • rapid growth in children with limited intake of iron • malabsorption • gastric resection • sprue • increased metabolic requirement • pregnancy, lactation or neoplasia

22. IRON DEFICIENCY Initial symptoms • easy fatigability • lack of appetite • headache • dizziness • palpitations then: hypochromic-microcytic anemia • microcytosis (small RBCs) • hypochromia (poor fill of hemoglobin) • poikilocytosis (bizarre shapes) • anisocytosis (variable/unequal sizes)

23. Diagnosis of iron deficiency • hematology (microcytichypochromic cells) • low serum iron • low serum ferritin ( indicates low body stores) • low hemosiderin • high total iron binding capacity (TIBC)

24. Treatment of iron deficiency • give 200 - 400 mg of iron per day • up to 25% of the iron preparation may be absorbed • parenteral iron is used in patients who have had bowel resections or in cases of inflammatory bowel disease • normally given IM (painful) • oral iron causes black stools, constipation, cramping • do not administer with antacids or metal chelators (tetracyclines)