Trace Minerals - Chapter 12 PDF

Trace Minerals Chapter 12 1  Trace Elements Body storage is less than 5 grams They are required in amounts less than 100 mg per day in the diet. The trace elements include: Iron * Iodine Zinc * Fluoride Copper *...

Trace Minerals Chapter 12 1  Trace Elements Body storage is less than 5 grams They are required in amounts less than 100 mg per day in the diet. The trace elements include: Iron * Iodine Zinc * Fluoride Copper * Chromium Manganese * Molybdenum Selenium 2  Iron (Fe) Total body content of iron.004% of body weight men - 3.6 grams (40 - 50 mg/kg body weight) women - 2.4 grams (35 - 50 mg/kg body weight) Storage – bone marrow, muscle, liver, spleen - Hb (in RBC) accounts for 80% of the body’s iron 3  Functions of Iron Major Function Cellular respiration - oxygen and CO2 transport The adult human body contains iron in two major forms: 1) functional iron (oxygen) 2) storage iron (iron) 4  Functions of Iron Air (oxygen) 1) functional iron in: hemoglobin – Hb in Lungs RBC transports oxygen blood blood in the blood to body cells and carries CO2 Hb + CO2 Hb + O2 away from cells for elimination by the lungs CO2 oxygen myoglobin - serves as an oxygen reservoir Myoglobin within muscle to make Muscle O2 available for muscle Metabolism contraction 5  Functions of Iron: Iron Recycled in the Body Some losses via sweat, skin, Transferrin carries and urine iron in blood. Some iron delivered to myoglobin of muscle Liver (and spleen) dismantles cells RBC, packages iron into Bone marrow incorporates transferrin, and iron into hemoglobin of stores excess iron in RBCs and stores ferritin and hemosiderin. excess iron in ferritin and hemosiderin. Some losses Iron-containing if bleeding hemoglobin in RBCs occurs carries oxygen. 2. Storage Iron: Ferritin and Hemosiderin – storage site for iron 6 Transferrin - Transports iron  Types of Dietary Iron: Heme and Nonheme Iron in Foods Only foods derived from animal flesh provide heme, but they also contain nonheme iron. Heme iron accounts for about 10% of the average daily iron intake, but it is well Key: absorbed (about 25%). Heme Nonheme iron accounts Nonheme for the remaining 90% but it is less well absorbed (about 17%). All the iron in foods derived from plants is nonheme iron. non-heme iron exists in 2 forms i) ferrous iron (Fe ++): reduced form ii) ferric iron (Fe+++): oxidized form Iron occurs in foods primarily as ferric iron 7 Iron absorption, transport, storage and loss. 8  Factors affecting iron absorption 1) acidity of digestive environment (),  antacids  the absorption of iron 2) vitamin C () 3) fructose () 4) MFP factor and protein () 5) tannic acid (tea, coffee, nuts) () 6) fibre () 7) oxalates (spinach, greens, bind to iron) () 8) calcium and phosphorous () 9) EDTA (ethylenediamine tetra-acetate, found in food additives) () 10) lead () 9  Iron from Meals A working estimate of absorbable iron can be calculated from 5 components of a meal: 1) total iron (mg) 2) heme iron 3) nonheme iron 4) Vitamin C 5) MFP factor 10  Iron Availability from Meals Meals can be Low Medium High classified as: High < 1oz M,F,P 1-3oz M,F,P >3oz M,F,P Medium Or Or Or Low < 25mg Vit C 25-75mg >75mg Vit C - availability of Vit C Or iron 1-3oz M,F,P By choosing plus your meals 25-75mg carefully, you Vit C can increase iron absorption 11  Iron deficiency If iron stores are depleted, the ability to synthesize hemoglobin is reduced Iron deficiency anemia takes a long time to develop because the elimination process is slow RBC – 120 days (4 months) Symptoms: fatigue, headache, pale (RBC contain less hemoglobin) 12  Iron Deficiency Causes: not enough dietary iron decreased absorption of iron hemorrhaging excessive blood donations – Iron content of blood – 0.5 mg/100ml – Donate blood (500 ml) – lose 2.5 mg iron It is estimated that as much as 80% of the world’s population may be iron deficient and 30% suffer from iron deficiency anemia. 13  Iron deficiency in Athletes i) can decrease performance because muscles lack oxygen ii) hemolysis (rupturing of RBC due to constant pounding (foot strike) during running) iii) female runners (menstruation) “sports anemia” – not a true anemia, however early in training, athletes may develop low blood Hb (temporary) - strenuous activity promotes destruction of the more fragile, older RBC, which reduces blood’s iron content temporarily - Strenuous activity also expands the blood’s plasma volume, thereby reducing the RBC count per unit of blood, but the RBC do not  in size or #, so oxygen-carrying capacity is not hindered * iron-deficincy anemia requires iron supplementation, but sports anemia does not. 14 Iron Deficiency Anemia Occurs when the oxygen carrying capacity of blood is decreased because there is insufficient iron to make hemoglobin. Diagnosed when either the volume of RBC (hematocrit), proteins containing iron (hemoglobin and ferritin), or serum iron levels are low. Normal RBC (a) appear larger and darker in colour than RBC in iron deficiency anemia (b). 15  Iron deficiency anemia Blood cells in iron-deficiency anemia are small (microcytic) and pale (hypochromic) because they contain less hemoglobin. 16 Iron Deficiency 17  Iron Toxicity Usually develops because the body lacks a mechanism for excreting excess iron therefore, iron accumulates in the body results in cell death (necrosis) Toxicity can also result from supplementation This condition is known as hemosiderosis Hemosiderosis: large deposits of the iron storage protein hemosiderin in the liver and other tissues Hemochromotosis: an advanced stage of hemosiderosis 18 Iron Toxicity 19 a: this value is an AI, all other values are RDAs Iron in human milk is more bioavailable than infant formula. If infants are not fed breast milk, iron fortified infant formula is recommended. b: value is RDA for a mixed diet 20  Dietary Sources of Iron 30 ml (2 tbsp) blackstrap molasses: 7 mg 250 ml cooked lentils: 6 mg 250 ml raw spinach: 2 mg 250 ml cooked spinach: 7 mg 100 g tofu: 5 mg 250 ml almonds: 4 mg 200 g sirloin steak: 4 mg 200 g chicken breast: 2 mg 200 g baked potato with skin: 2 mg Both plant and animal sources are good sources of iron (meat is absorbed better: heme iron) (cooking in iron pans increases the iron content of foods) 21 Iron content of foods: both animal and plant foods are good sources. 22  Zinc The adult body stores about 2 grams (.002% body weight) Found in all tissues, but high [ ]’s are found in the muscles and bones Also: - male reproductive organs (prostate glands, sperm) - pancreas, liver 23  Circulation of Zinc in the Body Zinc in food If the body Mucosal cells in does not the intestine store need zinc Zinc is excreted in excess zinc in shed intestinal cells. metallothionein. The pancreas uses zinc to make If the body digestive enzymes needs zinc and secretes them into the intestine. Metallothionein releases zinc to albumin and transferrin for transport to the rest of the body. 24  Zinc: Functions and Deficiencies Function Deficiency Sexual maturation (puberty) in Delayed sexual maturation males (puberty) in males Growth in children Delayed growth in children Component of insulin (regulates Impaired glucose regulation blood glucose) (hyperglycemia) Wound healing (synthesis of Poor wound healing, skin collagen) lesions Taste perception Impaired sense of taste Transports Vitamin A Night blindness Involved in the functioning of over 300 different enzymes, including superoxide dismutase (anti-oxidant) 25  Deficiency of Zinc Delayed growth in children Delayed sexual maturation (puberty) in males Middle Eastern diets are typically low in zinc containing foods (meat) and high in fibre Man on right, normal height Boy on left, 17 yrs old, 4 ft tall 26  Zinc Toxicity vomiting, diarrhea, headaches (due to supplementation not diet) Chronic Anemia - reduced Hb production (interferes with iron) Copper deficiency (zinc interferes with copper) Zinc lozenges are marketed to shorten the duration and severity of the common cold Research to date: Controversial and inconclusive Side effects of zinc lozenges: – nausea, bad taste reactions 27 Best Dietary Sources of Zinc: protein containing foods (animal products) 75 g 75 g crab Oysters 6 mg 59 mg 125 ml Garbanzo beans 90 g 1 mg Ham 1.7 mg 90 g beef 90 g 6 mg Chicken 1 mg RDA: Males 11 mg/day 28 Females 8 mg/day Zinc content of animal food sources 29 Zinc content of plant and animal food sources 30 Zinc content of food: Protein foods are the best sources 31  IODINE Distribution in the Body total iodine - 20 mg 75% - thyroid gland (hormones) 25% - all body tissues with higher [ ]’s in the skeletal muscle, blood, ovaries Iodine (referring to foods) is converted to iodide (referring to in the body) 32  Metabolism and Function of Iodine Iodine functions in the synthesis of 2 thyroid hormones: 1) thyroxine (T4) (also called tetra-iodothyronine) 2) triiodothyronine (T3) (active form) Synthesis of these 2 hormones begins with the formation of a large iodine containing protein called thyroglobulin Thyroglobulin – releases T4 and T3 in the blood – causing greater utilization of O2 – increases BMR 33  Deficiency of Iodine Goiter - a swelling of the thyroid when the diet is low in iodine, a hormone called TSH is released TSH - thyroid stimulating hormone (product of the pituitary gland); TSH is also called thyrotropin TSH - controls thyroid metabolism by increasing the # and size of the thyroid cells 34 Iodine and Thyroid When thyroid hormone Hormones levels drop too low, TSH is released and stimulates the thyroid gland to take up iodine and synthesize more hormones. If iodine is not available (brown arrows), thyroid hormones cannot be made and the stimulation continues, causing the thyroid gland to enlarge. 35  Deficiency of Iodine The thyroid gland will get larger in order to try to synthesize and release its hormones Goitre is a compensating mechanism for low serum levels of iodine 36 Deficiency of Iodine If the Goitre gets too large, it can interfere with breathing Goitre occurs more in women than men 37  Deficiency of Iodine Goitre can also develop by ingesting goitrogens Goitrogens interfere with the functioning of the thyroid gland (must be consumed in VERY, VERY large quantities to develop goitre) - cabbage - cauliflower - brussel sprouts - broccoli - turnip - mustard seeds - spinach - strawberries - peaches - peanuts, soybeans 38  Deficiency of Iodine Cretinism a severe iodine deficiency that affects the fetus during pregnancy irreversible causes mental and physical retardation Prevented by treatment of iodine during pregnancy 39  Toxicity of Iodine 25 - 50 times above the DRI Toxicity interferes with thyroid function The thyroid gland becomes overactive and gets larger so it can synthesize more hormones 40  Iodine: RDA and Dietary Sources DRI - 150 ug/day UL: 1100 ug/day table salt: all salt sold in Canada (including sea salt) must be iodized 2g of iodized salt (0.5 tsp) contains enough iodine to meet RDA (potassium iodide) Processed foods (because they contain table salt) other sources: seafood (ocean) (soil in the ocean is high in iodine) vegetables (grown in rich iodine soils) (not in this area of Canada) Since the introduction of iodized table salt in Canada, 1930’s, iodine deficiency is rare 41  Selenium Main function: Antioxidant (spares Vitamin E) Part of the enzyme glutathione peroxidase, which prevents free-radical formation and protects cell membrane destruction 42 Selenium Spares Vitamin E 43  Deficiency of Selenium Keshan’s disease - heart disease caused by selenium deficiency (heart enlargement) Mild deficiency: impaired heart function Severe deficiency: heart failure First reported by the Chinese The disease is prevalent in regions where the soil is poor in selenium Cause of Keshan’s disease is unknown however, adding selenium to the diet seems to prevent it 44  Toxicity of Selenium Works as a pro-oxidant found in regions where soil is high in selenium or supplementation - long term ingestion of 1 mg or more/day symptoms damage to nervous tissue (CNS disorders) damage to skin (rash), hair (loss), nails (brittle) chronic fatigue/irritability garlic breath odor 45  Selenium: DRI/dietary sources RDA: 55 ug/day (M + F) UL: 400 ug/day Protein sources Whole grains 46 Selenium in the Diet 47  Copper The body stores about 100 mg Variety of tissues (muscles, liver, brain, highest storage) Main Function In plasma, about 95% occurs as the copper-protein complex called ceruloplasmin ceruloplasmin is important in iron metabolism (ferrous to ferric iron), contributing to iron absorption and formation of Hemoglobin 48  Copper – Other Functions Defend against free radicals (superoxide dismutase*) Synthesize collagen (lysyl oxidase*) Energy metabolism (ETC) (cytochrome C oxidase*) (* Copper containing enzymes) 49  Copper Deficiency (Rare) Animal studies: raises blood cholesterol, damages blood vessels (question about deficiency leading to CVD in humans: inconclusive) excess zinc, iron, and Vitamin C interferes with copper 50  Copper Deficiency (rare genetic disorder) May result in anemia (due to copper’s role in iron metabolism) Menkes Disease (use to be called Menke’s Kinky Hair Syndrome) rare genetic disorder defect of copper absorption from the intestine Symptoms rapid degeneration of nerve tissue skeletal abnormalities a “steely” texture of the hair (there is a defective keratinization and pigmentation of the hair) light patches or streaks in hair (white) 51  Copper - toxicity Toxicity is rare from diet but can be seen in supplementation (more than 20 mg) name of supplement: cupric oxide symptoms - vomiting, diarrhea 52  Copper toxicity (rare genetic disorder) Wilson’s disease - an inherited condition that produces copper toxicity because of defective excretion (progressive) Copper accumulates in the liver and brain Symptoms tissue necrosis (esp in the liver) mental deterioration tremor loss of coordination Treatment: low copper diet and drugs (also zinc supplements) that bind the copper and allows it to be excreted in the urine 53  DRI/Dietary Sources of Copper RDA: 900 ug/day UL: 10,000 ug/day (10 mg/day) Water (copper plumbing) Richest dietary source: organ meat Seafood Nuts, seeds Legumes Whole grains 54  Manganese Total body content - 20 mg dietary calcium and iron decrease Mg absorption Functions: acts as a cofactor in enzymes (cofactor – a substance that binds to an enzyme to activate it) Assist in bone formation (normal growth) CHO metabolism - conversion of pyruvate to a compound in the Kreb’s cycle (_____________) Needed for the activity of superoxide dismutase (like copper and zinc) 55  Toxicity of Manganese Not usually found from dietary intake has been found in miners of manganese ore mines (inhale dust) Symptoms tremor loss of coordination 56  DRI/Dietary Sources Manganese AI: males 2.3 mg/day AI: females 1.8 mg/day UL: 11 mg/day Best Sources: Whole grains, Nuts, Legumes Green leafy vegetables Tea 57  FLUORIDE Body contains less than 1 gram absorption is mainly in the stomach and SI approx. 1/2 is retained in the teeth and bones Function Protects bone and dental tissue bone containing fluoride is more stable and more resistant to degeneration (may prevent osteoporosis?) fluoride also helps teeth become resistant to decay 58  Protection of bones and teeth - Fluoride When bones and teeth become calcified, - a crystal is formed from calcium and phosphorous this crystal is called hydroxyapatite - the fluoride then replaces the OH group of the crystal hydroxyapatite to form fluorapatite fluoroapatite deposits on the bones and teeth to protect them and prevent tooth decay 59  Fluoride: dietary sources Dietary Sources: drinking water (not all cities, not in most bottled water), toothpaste, fish, tea Research Study: Brampton, Mississauga, Caledon Children in Mississauga and Brampton had fewer cavities (37%) than children in Caledon (50%) Why? Brampton and Mississauga have fluoridated water, Caledon does not 60  Research on Fluorididated Water Hutton, W. L., Brantford-Sarnia-Stratford fluoridation caries study Brantford, ON became the 1st city in Canada to artificially fluoridate its water The development of dental cavities was compared in Brantford, Stratford (naturally fluoridated water), and Sarnia (no fluoride in the water supply) Results: 1% of Sarnia children were cavity free 16% of Brantford and Stratford children were cavity free Children who had decay free permanent incisors Sarnia children: 50% Brantford children: 87% Stratford children: 89% This study, along with other research, was used to make recommendations to fluoridate water supplies that do not have fluoride 61 Fluoride and Dental Carries in Children 62  Deficiency/Toxicity of Fluoride Deficiency Tooth decay, imperfect development of teeth Toxicity (over 20mg over many years) Fluorosis - a condition of the teeth due to ingestion of too much fluoride (found in areas where fluoride content in water is very high) teeth become “mottled” or stained (looks like tea, coffee, or smoking stains) Fluorosis - toxicity Toxicity does NOT occur from drinking water containing NORMAL amounts of fluoride!! Toxicity does NOT occur from using toothpaste with fluoride!! (however, there are guidelines for children under 12 and toothpaste) 63  Fluoride Myths Fluoride increases the risk of developing cancer NO research to date has found a correlation between fluoride and cancer 64  DRI of Fluoride Health Canada recommends that the water supply should be fluoridated to 1ppm (1mg per litre) AI (males): 4 mg/day AI (females): 3 mg/day UL: 10 mg/day 65  Chromium The major function is to enhance the activity of insulin in the metabolism of glucose (glucose tolerance factor (GTF)) particularly in maintaining the rate at which glucose is removed from blood for uptake into muscle and liver impaired glucose tolerance can result from a chromium deficiency However, chromium supplementation has not been shown to improve glucose or insulin responses in diabetics 66  Chromium dietary sources/DRI GTF has been purified in brewers yeast, therefore is found in yeast (bread) and beer Main Dietary Sources: Whole grains, nuts, meats AI (males): 35 ug/day AI (females): 25 ug/day UL: none, no toxic effects have been found 67  Molybdenum Functions as a cofactor for many enzymes as a part of xanthine oxidase, it plays a role in the: - metabolism of nucleic acids (RNA, DNA) - formation of uric acid xanthine oxidase also contains iron, therefore molybdenum is important in the mobilization of ferritin iron from liver reserves RDA: 45 ug/day UL: 2 mg/day Dietary sources: milk, grains, legumes, organ meats 68 Summary of Trace Elements: Table 12.1 in textbook Slides 70 and 71 are the same summary 69 Summary of Trace Elements 70 Summary of Trace Elements (continued) 71 Benefits and Risks of Trace Element Supplements 72  Review Questions ___and ____(iron storage proteins) 1. transferrin ______ Iron transport protein 2. heme ______ oxygen-holding protein of 3. ferritin the muscle cell 4. myoglobin 5. hemosiderin 6. hemotocrit 73  Review Questions The iron content of blood is approximately ________________ mg/100ml blood Excess iron may cause ______________________________, a condition characterized by deposits of the iron storage protein ________________________ in the liver, heart, joints, and other tissues. ___________________________ releases zinc to albumin and transferrin for transport to the rest of the body. What food group provides the most amount of zinc? Iodine functions in the production of two thyroid hormones. Name them. What is the main function of selenium? Copper is necessary for the absorption and use of _____________ in the formation of Hb. 74  Review Questions Manganese toxicity is more likely to occur from __________________________________________________________ rather than dietary sources. Manganese acts as a cofactor for many enzymes that facilitate the metabolism of CHO, fat, protein, specifically helps in the conversion of pyruvate to _______________________. Fluoride toxicity is called _______________________________. What is the main function of fluoride? Water should contain ______________ of fluoride. What is the main function of chromium? Molybdenum functions as a cofactor for metalloenzymes. As a part of _________________________________________in the metabolism of nucleic acids and the formation of uric acid. 75