The Trace Minerals. Chapter Cengage Learning. All Rights Reserved.

Transcription

1 The Trace Minerals Chapter 13

2 The Trace Minerals An Overview Trace mineral contents of foods Vary with soil and water composition, and food processing Deficiencies Can affect people of all ages May be difficult to recognize Toxicities FDA does not regulate trace minerals in supplements

3 RDA (or AI) and UL Compared for Selected Trace Minerals

4 Interactions Common and well coordinated to meet body needs Sometimes lead to nutrient imbalances Excess of one causes a deficiency in another Or interfere with work of another mineral Contaminant minerals and toxic reactions Nonessential trace minerals Nickel, silicon, vanadium, cobalt, boron More needs to be learned

5 Iron Too little and too much can be harmful Roles in the body Switches back and forth between two forms Ferrous iron Ferric iron Cofactor in oxidation-reduction reactions Part of electron carriers Hemoglobin and myoglobin

6 Iron, continued Absorption Body conserves iron Balance maintained primarily through absorption Ferritin Iron storage in small intestine Transferrin Iron transport protein

7 Iron Absorption Process

8 Iron in food 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. 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. Stepped Art Iron absorption process

9 Heme and Nonheme Iron Types of iron Heme iron Found in animal foods High bioavailability Nonheme iron Found in plant and animal foods Absorption-enhancers for nonheme iron MFP Vitamin C Some acids and sugars

10 Heme and Nonheme Iron in Foods

11 About 40% of the iron in meat, fish, and poultry is bound into heme; the other 60% is nonheme iron. Key: Heme Nonheme All of the iron in foods derived from plants is nonheme iron. Heme accounts for about 10% of the average daily iron intake, but it is well absorbed (about 25%). Nonheme iron accounts for the remaining 90%, but it is less well absorbed (about 17%). Stepped Art - Heme and nonheme iron in foods

12 Factors that Inhibit Iron Absorption Phytates Vegetable proteins Calcium Polyphenols Dietary factors combined Individual variation in absorption Health, stage in life cycle, and iron status

13 Iron Transport and Storage Transferrin delivers iron to bone marrow and other tissues Storage Ferritin Hemosiderin Recycling Balance Regulating hormone hepcidin

14 Iron Recycled in the Body

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

16 Iron Deficiency Most common nutrient deficiency worldwide Populations affected in United States Link with obesity Vulnerable stages in life Women in reproductive years Pregnancy Infants and young children Adolescence

17 Assessment of Iron Deficiency Even small blood losses can cause deficiency Deficiency develops in stages Iron stores diminish serum ferritin Decrease in transport iron transferrin Hemoglobin and hematocrit values decline Iron deficiency and anemia Anemia severe depletion of iron stores Low hemoglobin concentrations Symptoms

18 Normal Blood Cells and Blood Cells in Iron Deficiency Anemia Compared

19 Results of Iron Deficiency Behavioral symptoms Energy metabolism is impaired Neurotransmitter synthesis is altered Reduces work capacity and mental productivity Motivational problems Pica Craving and consumption of nonfood substances

20 Iron Overload Hereditary hemochromatosis Most common genetic disorder in United States Hemosiderosis Signs and symptoms Transferrin saturation and serum ferritin Characteristics of condition Treatment Research: targeting hepcidin activity

21 Iron and Chronic Diseases Heart disease Excess iron Free radicals Cancer Free radical damage Limited evidence Iron poisoning Symptoms of toxicity UL

22 Iron Sources Natural sources Meats, fish, poultry, legumes, eggs Enriched sources Flour and grain products Iron cookware RDAs Vegetarians Women Maximizing absorption

23 Iron in Selected Foods Food (Best Source per kclalorie) Serving Size (kcalories) Food Group Approximate Amount of Iron (milligrams) Bread, whole wheat 1 oz slice (70 kcal) Grains 1 Cornflakes, fortified 1 oz (110 kcal) Grains 0.9 Spaghetti pasta ½ c cooked (99 kcal) Grains 1 Tortilla, flour 1 10"-round (234 kcal) Grains 2.4 Broccoli ½ c cooked (22 kcal) Vegetables 0.6 Carrots ½ c shredded raw (24 kcal) Vegetables 0.3 Potato 1 medium baked w/skin (133 kcal) Vegetables 1.8 Tomato juice ½ c (31 kcal) Vegetables 1 Banana 1 medium raw (109 kcal) Fruits 0.5 Orange 1 medium raw (62 kcal) Fruits 0.1 Strawberries ½ c fresh (22 kcal) Fruits 0.3 Watermelon 1 slice (92 kcal) Fruits 0.4 Milk 1 c reduced-fat 2% (121 kcal) Milk and milk products 0.1 Yogurt, plain 1 c low-fat (155 kcal) Milk and milk products 0.1 Cheddar cheese 1½ oz(171 kcal) Milk and milk products 0.2 Cottage cheese ½ c low-fat 2% (101 kcal) Milk and milk products 0.1 Pinto beans ½ c cooked (117 kcal) Legumes, nuts, seeds 2.2 Peanut butter 2 tbs (188 kcal) Legumes, nuts, seeds 0.4 Sunflower seeds 1 oz dry (165 kcal) Legumes, nuts, seeds 1 Tofu (soybean curd) ½ c (76 kcal) Legumes, nuts, seeds 1.2 Ground beef, lean 3 oz broiled (244 kcal) Meats, poultry, seafood 2 Chicken breast 3 oz roasted (140 kcal) Meats, poultry, seafood 1 Tuna, canned in water 3 oz (99 kcal) Meats, poultry, seafood 1.3 Egg 1 hard cooked (78 kcal) Meats, poultry, seafood 0.8 Excellent, and sometimes unusual, sources: Clams, canned 3 oz (126 kcal) Meats, poultry, seafood 18+ Beef liver 3 oz fried (184 kcal) Meats, poultry, seafood 5.4 Parsley 1 c raw (22 kcal) Vegetables 3.9

24 Some of Zinc s Roles in the Body Supports the work of hundreds of proteins Stabilizes cell membranes and DNA Immune function Growth and development Synthesis, storage, and release of insulin Blood clotting Thyroid hormone function Behavior and learning performance

25 Zinc Absorption Rate varies depending on amount consumed percent May be used or retained in intestinal cells Recycling Small intestine Two doses of zinc Enteropancreatic circulation Zinc losses

26 Enteropancreatic Circulation of Zinc

27 Zinc in food The pancreas uses zinc to make digestive enzymes and secretes them into the intestine. Mucosal cells in the intestine store excess zinc in metallothionein. If the body needs zinc 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. Metallothionein releases zinc to albumin and transferrin for transport to the rest of the body. Stepped Art - Enteropancreatic circulation of zinc.

28 Zinc Transport and Deficiency In the blood Albumin Transferrin Deficiency Widespread in developing world Middle Eastern diets inhibit zinc absorption Effects Growth retardation Impaired immune response Central nervous system damage

29 Zinc Toxicity and Sources Symptoms Interference with copper metabolism Sources Protein-rich foods Shellfish, meats, poultry, milk, and cheese Supplementation Developing countries May shorten duration of common cold

30 Zinc in Selected Foods Food (Best Source per kclalorie) Serving Size (kcalories) Food Group Approximate Amount of Zinc (milligrams) Bread, whole wheat 1 oz slice (70 kcal) Grains 0.6 Cornflakes, fortified 1 oz (110 kcal) Grains 0.1 Spaghetti pasta ½ c cooked (99 kcal) Grains 0.5 Tortilla, flour- 1 10"-round (234 kcal) Grains 0.6 Broccoli ½ c cooked (22 kcal) Vegetables 0.4 Carrots ½ c shredded raw (24 kcal) Vegetables 0.1 Potato 1 medium baked w/skin (133 kcal) Vegetables Tomato juice ¾ c (31 kcal) Vegetables 0.4 Banana 1 medium raw (109 kcal) Fruits 0.2 Orange 1 medium raw (62 kcal) Fruits 0.1 Strawberries ½ c fresh (22 kcal) Fruits 0.1 Watermelon 1 slice (92 kcal) Fruits 0.3 Milk 1 c reduced-fat 2% (121 kcal) Milk and milk products 1 Yogurt, plain 1 c low-fat (155 kcal) Milk and milk products 2.1 Cheddar cheese 1½ oz(171 kcal) Milk and milk products 1.4 Cottage cheese ½ c low-fat 2% (101 kcal) Milk and milk products 0.7 Pinto beans ½ c cooked ( 117 koal) Legumes, nuts, seeds 1 Peanut butter 2 lbs (188 koal) Legumes, nuts, seeds 1 Sunflower seeds 1 oz dry (165 kcal) Legumes, nuts, seeds 1.5 Tofu (soybean curd) ½ c (76 kcal) Legumes, nuts, seeds 0.9 Ground beef, lean 3 oz broiled (244 kcal) Meats, poultry, seafood 4.2 Chicken breast 3 oz roasted (140 kcal) Meats, poultry, seafood 0.9 Tuna, canned in water 3 oz (99 kcal) Meats, poultry, seafood 0.8 Egg 1 hard cooked (78 kcal) Meats, poultry, seafood 0.6 Excellent, and sometimes unusual, sources: Oysters 3 oz cooked (139 kcal) Meats, poultry, seafood 12+ Sirloin steak, lean 3 oz broiled (172 kcal) Meats, poultry, seafood 5.7 Crab 3 oz cooked (94 kcal) Meats, poultry, seafood

31 Iodine GI tract converts iodine in food to iodide Iodide: readily absorbed by the body Roles in the body Part of thyroid hormones that regulate: Body temperature Metabolic rate Reproduction and growth Blood cell production Nerve and muscle function

32 Iodine Deficiency Thyroid hormone production declines Increased secretion of thyroidstimulating hormone (TSH) Cells of thyroid expand: goiter Goitrogen Preventable mental retardation and brain damage Cretinism

33 Iodine Toxicity and Sources Toxicity Interferes with thyroid function Enlarges thyroid gland Goiter in an infant UL Recommendations Sources Seafood Iodized salt

34 Selenium Substitute for sulfur in some amino acids Methionine, cysteine, and cystine Roles in body Antioxidant Part of proteins Glutathione peroxidase Enzymes activate or inactivate thyroid hormone

35 Selenium Deficiency Keshan disease Type of heart disease in regions of China where soil lacks selenium Cancer May be protective factor Supplements have not proved effective Toxicity UL Effects

36 Selenium Sources Found in soil Meats, milk, and eggs Brazil nuts Recommendations RDA Amount needed to maximize glutathione peroxidase activity

37 Copper Transport and balance depend on a system of proteins Roles in body Constituent of enzymes Reactions that consume oxygen or oxygen radicals Iron metabolism Defense against oxidative damage Other roles

38 Copper Deficiency and Toxicity Possible link to cardiovascular disease United States diets provide adequate intake Excessive intakes Foods versus supplements Genetic disorders that effect copper status Menkes disease Wilson s disease

39 Copper Sources Legumes Whole grains Nuts Shellfish Seeds Water delivered through copper plumbing

40 Manganese Body locations Bones Metabolically active organs Roles in body Cofactor for enzymes that facilitate metabolism Bone formation Conversion of pyruvate to a TCA cycle compound

41 Manganese Deficiency Requirements are low Deficiencies are rare Factors that limit manganese absorption Toxicity Environmental contaminate UL Recommendations AI set based on average intakes Source: grain products

42 Fluoride Found in bones and teeth Fluorapatite Dental caries Sources Drinking water Most bottled waters lack fluoride Tea and fish Toxicity: fluorosis

43 Chromium Roles in the body Participates in carbohydrate and lipid metabolism Helps maintain glucose homeostasis Diabetes-like condition may result if chromium lacking Sources Unrefined foods Liver, brewer s yeast, whole grains Supplements

44 Molybdenum Working part of several metalloenzymes Dietary deficiencies are unknown Sources Legumes, breads, grain products, leafy green vegetables, milk, and liver Toxicity is rare UL Characteristics

45 Contaminant Minerals Impair body s growth, work capacity, and general health Heavy metals Lead Indestructible Displaces nutrient minerals from metabolic sites Children with iron deficiency especially vulnerable Mercury Cadmium

46 Closing Thoughts on the Nutrients Look at nutrients as a whole Work cooperatively with one another Actions are most often interactions Most foods deliver multiple nutrients

47 Phytochemicals and Functional Foods Highlight 13

48 Phytochemicals Found in plant-derived foods Have biological activity in the body Physiological effects May prevent development of chronic diseases Adverse effects if consumed in excess Functional foods

49 Phytochemicals and Cancer Protect against DNA damage Soybeans Phytoestrogens Tomatoes Lycopene

50 Phytochemicals and Heart Disease Flavonoids Food sources Heart-protection factors Carotenoids Plant sterols Lignans Defending against other diseases

51 Functional Foods All foods that have a potentially beneficial effect on health Whole Fortified Modified Characteristics similar to drugs Long term consumption may be necessary for beneficial effect Cost

52 The Colors of Foods Rich in Phytochemicals Red White-Brown Orange-Yellow Blue-Purple Green Anthocyanins Lycopene Beets Cherries Cranberries Pink grapefruit Pomegranates Radicchio Radishes Raspberries Red apples Red peppers Red potatoes Rhubarb Strawberries Tomatoes Watermelon Allicin Allyl sulfides Bananas Brown pears Cauliflower Chives Dates Garlic Ginger Leeks Mushrooms Onions Parsnips Shallots Turnips Beta-carotene Limonene Apricots Cantaloupe Carrots Lemons Mangoes Nectarines Oranges Papayas Peaches Persimmons Pineapple Pumpkin Rutabagas Squash Sweet potatoes Tangerines Yellow peppers Anthocyanins Ellagic acid Phenolics Black currants Blackberries Blueberries Dried plums Eggplant Elderberries Plums Purple figs Purple peppers Raisins Purple cabbage Purple grapes Beta-carotene Lutein Indoles Artichokes Arugula Asparagus Avocados Broccoli Brussels sprouts Cabbage Celery Cucumbers Endive Green apples Green beans Green grapes Green onions Green pears Green peppers Honeydew melon Kiwifruit Leafy greens Limes Okra Peas Snow peas Spinach Sugar snap peas Zucchini

53 Unanswered Questions Research on safety and effectiveness still in progress While products are available for purchase Questions to ask Does it work? How much does it contain? Is it safe? Is it healthy? Future foods