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Chapter 12 Lecture Chapter 12: Nutrients Involved in Blood Health and Immunity © 2017 Pearson Education, Inc. Blood • Functions • Transports nutrients and oxygen to cells • Removes waste products generated from metabolism • Immune function (white blood cells) • Mechanism for heat transfer © 2017 Pearson Education, Inc. Components of Blood • Erythrocytes: red blood cells transport oxygen through the body • Leukocytes: white blood cells are key to our immune system • Platelets: cell fragments assist in blood clotting • Plasma: fluid portion of the blood maintains adequate blood volume © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Micronutrients That Maintain Healthy Blood • Minerals • Iron • Zinc • Copper • Vitamins • Vitamin K • Vitamin B6 • Folate • Vitamin B12 © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Iron • Iron is a trace mineral • Component of oxygen-carrying hemoglobin in erythrocytes and myoglobin in muscles • Heme groups depend on iron to carry oxygen in hemoglobin • Component of cytochromes, electron carriers within the metabolic pathways for energy production from macronutrients • Part of antioxidant enzyme system • DNA synthesis and cognitive development © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Maintaining Iron Homeostasis • Regulation of iron digestion, absorption, transport, storage, and excretion • Factors that alter iron digestion and absorption • Individual's iron status • Level of dietary iron consumption • Type of iron in foods • Amount of stomach acid for digestion • Dietary factors enhance or inhibit absorption © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Iron • Two types of iron in foods • Heme iron: part of hemoglobin and myoglobin, found only in animal-based foods and more absorbable • Non-heme iron: found in both plant and animals, not as easily absorbed • Majority of iron in food (90–95%) is nonheme iron • Iron in animal-based food is 50–60% heme iron © 2017 Pearson Education, Inc. Iron (cont.) • Factors that enhance iron absorption • Meat factor • Stomach acids • Vitamin C © 2017 Pearson Education, Inc. Iron (cont.) • Factors that impair iron absorption • Phytate (legumes, rice, and whole grains) • Polyphenols (oregano, red wine, tea, coffee) • Vegetable proteins • Fiber • Calcium • Bioavailability of iron from vegan diet is approx. 1–10%, vs. typical Western diet's absorption of 14–18% © 2017 Pearson Education, Inc. Iron (cont.) • Iron transport • Ferroportin: transports iron and regulates intestinal absorption and release • Transferrin: iron-transport protein in blood • Receptors on cells transport iron into cells • Iron storage • Ferritin (primary) and hemosiderin (overflow) help meet iron needs • Liver, bone marrow, and spleen © 2017 Pearson Education, Inc. Regulation of Total Body Iron • Absorption depends on: • Amount consumed • Amount needed • Dietary factors affecting absorption • Losses • Major loss in turnover of gut enterocytes • Lost in feces, menses, blood donations • Storage and recycling • As cells break down, iron is recycled and returned to body's iron pool © 2017 Pearson Education, Inc. Iron (cont.) • Recommended intake • RDA varies based on age and gender • 8 mg/day for adult men • 18 mg/day for adult women,19−50 years • 27 mg/day for pregnant women • Sources of iron • Meat, poultry, fish, clams, oysters, liver, enriched or fortified cereals and breads • Supplements © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Too Much Iron • Accidental iron overdose: most common cause of poisoning deaths in children • Symptoms: nausea, vomiting, diarrhea • Hemochromatosis: excessive absorption of dietary iron and altered iron storage • Treatment: reduce dietary iron, avoid high vitamin C intake, blood removal, chelation drugs © 2017 Pearson Education, Inc. Not Enough Iron • Most common nutrient deficiency in the world • High risk: infants, young children, adolescent girls, premenopausal and pregnant women • Poor dietary intakes • Iron losses in blood and sweat • Diets high in fiber or phytates that bind iron • Low stomach acid • Poor iron absorption: poor gut health or dietary supplements with high mineral levels (e.g., calcium) © 2017 Pearson Education, Inc. Stages of Iron Deficiency • Iron depletion (stage I) is caused by a decrease in iron stores • Iron-deficiency erythropoiesis (stage II) occurs with decreased iron transport • Iron-deficiency anemia (stage III) results in reduced normal, healthy red blood cell production, decreased size, inadequate hemoglobin © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Zinc • Zinc is a trace mineral • Functions of zinc • Component of enzymes (heme synthesis) • Maintain structural integrity and shape of proteins (zinc fingers) • Assist in regulating gene expression © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Zinc (cont.) • Metallothionein regulates absorption and release • Absorption increases with need: growth, sexual development, pregnancy • Dietary factors inhibit zinc absorption • High non-heme iron intake • Phytates and fiber (whole grains, beans) • Dietary factor enhances zinc absorption • Animal-based protein © 2017 Pearson Education, Inc. Zinc (cont.) • RDA: 8 mg/day for women, 11 mg/day for men • Sources of zinc • Red meats, some seafood, whole grains, enriched grains and cereals © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Too Much Zinc • Toxicity can occur from supplements • Symptoms: intestinal pain, cramps, nausea, vomiting • Depressed immune function • Decreased high-density lipoprotein concentrations • Interference with copper and iron absorption © 2017 Pearson Education, Inc. Not Enough Zinc • Deficiencies are uncommon in the United States • Symptoms: growth retardation, diarrhea, delayed sexual maturation, hair loss, impaired appetite, infections • Lack of good assessment parameters for zinc © 2017 Pearson Education, Inc. Copper • Copper is a trace mineral • Functions of copper • Required for iron transport • Cofactor in energy metabolism and for connective tissue production • Part of superoxide dismutase antioxidant enzyme system • Regulates neurotransmitters (serotonin) © 2017 Pearson Education, Inc. Copper • Factors that promote copper absorption • More copper is absorbed with low-copper diet • Factors that impair copper absorption • High zinc intakes • High iron intakes © 2017 Pearson Education, Inc. Copper • Recommended intake • RDA for adults is 900 µg/day • Sources of copper • Organ meats, seafood, nuts, seeds, wholegrain foods © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Copper • Too much copper • Toxicity is not well studied in humans • Symptoms: abdominal pain, nausea, diarrhea, vomiting, liver damage (Wilson disease) • Not enough copper • Copper deficiency is rare • Symptoms: anemia, reduced white blood cells, osteoporosis (children—bone demineralization) © 2017 Pearson Education, Inc. Vitamin K • Vitamin K is a fat-soluble vitamin important for both bone and blood health • Function of vitamin K • Coenzyme assists in synthesizing blood coagulating proteins: prothrombin and procoagulants, factors VII, IX, and X © 2017 Pearson Education, Inc. Vitamin K • Factors that promote vitamin K absorption • Gastrointestinal bacteria produce vitamin K • Dietary need depends on intestinal health • Factors that impair vitamin K absorption and synthesis • Impaired dietary fat absorption • Excessive broad-spectrum antibiotics © 2017 Pearson Education, Inc. Vitamin K • Recommended intake • AI for adults is 90 µg/day for women;120 µg/day for men • No established UL at this time • Sources of vitamin K • Green leafy vegetables, such as collard greens, kale, spinach, cabbage • Soybean and canola oils © 2017 Pearson Education, Inc. Vitamin K • Too much vitamin K • No known side effects • Not enough vitamin K • Deficiency is rare • Blood fails to clot, bleeding, hemorrhaging • Fat malabsorption • Newborns lack intestinal bacteria to produce vitamin K (injection at birth) © 2017 Pearson Education, Inc. Vitamin B6 • Essential for heme synthesis • Integral part of the heme complex • RDA for adults is 1.3 mg/day, 1.5 mg/day for older women and 1.7 mg/day for older men; UL is 100 mg/d © 2017 Pearson Education, Inc. Vitamin B6 • Good sources include meats, poultry, fish, soybased foods, cereals, and starchy vegetables • Deficiency can cause microcytic hypochromic anemia and impairs protein metabolism • Toxicity with high-dose supplements, affecting nerves © 2017 Pearson Education, Inc. Folate • One of the B vitamins • Folate used for all forms of food folate with biological function, folic acid in supplements, enriched and fortified foods • Functions of folate (coenzyme) • DNA and amino acid synthesis • Cellular division and differentiation • Functions with B12 and B6 metabolism © 2017 Pearson Education, Inc. Folate • Recommended intake • RDA : 400 µg/day adults, 600 µg/day during pregnancy • Sources of folate • Fortification to minimize birth defects (neural tube defects): enriched breads, flours, pasta, grain products • Liver, spinach, lentils, oatmeal, asparagus © 2017 Pearson Education, Inc. Folate • Four states of folate deficiency similar to iron: 1. Negative folate balance (stage I) 2. Folate depletion (stage II) 3. Folate deficiency erythropoiesis (stage III) 4. Folate deficiency anemia (stage IV) © 2017 Pearson Education, Inc. Folate • Macrocytic anemias are larger than normal red blood cells that inhibit adequate oxygen transport • Symptoms (similar to microcytic anemia) include fatigue, irritability, difficulty concentrating, headaches, shortness of breath, reduced capacity for work • Similar symptoms can result from vitamin B12 deficiency, so it's important to distinguish the cause © 2017 Pearson Education, Inc. Vitamin B12 • Functions • Coenzyme for DNA synthesis • Regeneration of folic acid • Alterations in status mimic those seen with iron and folate © 2017 Pearson Education, Inc. Vitamin B12 • Recommended intake • RDA for adults is 2.4 µg/day • Sources of vitamin B12 • Found primarily in dairy products, eggs, meats, poultry, fish, and shellfish (animal sources) • Vegan diet may obtain vitamin B12 from fortified foods, supplements, or injections © 2017 Pearson Education, Inc. Vitamin B12 • Factors that alter vitamin B12 digestion, absorption, and balance • Requires acidic environment (stomach) and protein intrinsic factor for absorption • Stored in the liver • Four levels of vitamin B12 deficiency © 2017 Pearson Education, Inc. Vitamin B12 • Too much vitamin B12 • No known adverse effects • Not enough vitamin B12 • Deficiency is rare, but associated with dietary insufficiency or reduced absorption • Gastrointestinal and neurologic effects (destroyed myelin sheaths) • Pernicious anemia (macrocytic) results in reduced intrinsic factor production © 2017 Pearson Education, Inc. Immune System • A healthy immune system: • Protects the body from infectious diseases • Helps heal wounds • Guards against the development of cancers • How does it function? • Nonspecific immune function • Specific immune function © 2017 Pearson Education, Inc. Nonspecific Immune System • Body's primary defense against microbes, airborne particles, venom, ingested toxins • Also called innate immunity • Intact skin and healthy mucous membranes • Stomach acid destroys food-borne bacteria • Inflammatory response causes discomfort, loss of appetite, fatigue, and fever © 2017 Pearson Education, Inc. • A macrophage is a type of nonspecific immune cell. The one shown here is about to engulf an invading microbe. © 2017 Pearson Education, Inc. Specific Immune System • Directed against recognized antigens • Induces antibodies to destroy invader • Memory cells remain in circulation • Two main types of cells: B cells and T cells • Acquiring specific immunity • Have disease or vaccinations (immunizations) • Maternal antibodies • Antiserum injection (snakebite) © 2017 Pearson Education, Inc. Immune System • Malfunction causes chronic inflammation and infection • Allergic reactions • Autoimmune response • Common in malnourished • Immune deficiency diseases © 2017 Pearson Education, Inc. Nutrition and the Immune System • A nourishing diet provides all the nutrients the immune system needs • Single-nutrient subclinical deficiencies can cause subtle abnormalities in immunity • Protein-energy malnutrition and severe micronutrient deficiencies reduce immune function © 2017 Pearson Education, Inc. Protein-Energy Malnutrition • Malnutrition increases the risk for infection • Infection depresses appetite and often causes vomiting and diarrhea • Decreased appetite, vomiting, and diarrhea cause malnutrition, which increases vulnerability to infection • Decreased immunocompetence is a sensitive indicator of reduced nutritional status © 2017 Pearson Education, Inc. Obesity • • • • Increases incidence of infections Delays wound healing Poor antibody response to vaccination Inflammatory state may increase asthma, hypertension, cardiovascular disease, and type 2 diabetes among obese individuals © 2017 Pearson Education, Inc. Essential Fatty Acids • Essential fatty acids are precursors for signaling molecules eicosanoids • Supplementation with EPA and DHA reduces inflammation and may treat chronic inflammatory conditions like rheumatoid arthritis, inflammatory bowel disease, and cardiovascular disease © 2017 Pearson Education, Inc. Vitamins and Minerals • Vitamin A maintains mucosal surface • Vitamins C and E protect cell membrane from reactive oxygen species • Zinc important for immune function, gene expression and enzyme activation (B and T cell proliferation) © 2017 Pearson Education, Inc. Vitamins and Minerals (cont.) • Selenium: • Coenzyme for glutathione peroxidase • Promotes B and T cell proliferation • Antibody production • Iron and copper: • Part of superoxide catalase and dismutase • Deficiencies reduce immune response (B and T cell function) • Excessive iron can impair immunity © 2017 Pearson Education, Inc. Infections Alter Nutrient Status • Reduced food intake: illness/infection reduces appetite and overall energy intake • Increased nutrient loss (diarrhea, vomiting, inflammation) • Increased resting metabolic rate with fever • Redistribution of energy and nutrients to enhance the immune response © 2017 Pearson Education, Inc.