CH-15 Trace Minerals – Wardlaw’s Perspectives in Nutrition : Chapter Notes

This document contains Chapters 15 to 16 Chapter 15 Trace Minerals Overview In Chapter 15, the authors present the history, sources, chemistry, functions, metabolism, and requirements of the trace minerals - those required in amounts of less than 100 mg/day. Trace minerals include iron, zinc, copper, manganese, iodine, selenium, chromium, and fluoride. Many of the trace minerals function as cofactors for enzymes that are essential for a variety of human functions, from metabolism of nutrients, to antioxidant systems, to synthesis of structural components. Iron is vital for transport of oxygen to body cells, among many other roles. Zinc is needed for normal growth and development. Iodine is required for thyroid function. Fluoride protects teeth from dental caries. The ultratrace minerals are an area of active research - many of their requirements and functions are still unknown, yet molybdenum, arsenic, boron, vanadium, silicon, and nickel are essential in human diets. Learning Objectives Discuss the major functions of each trace mineral. List 3 important food sources for each trace mineral. Describe how each trace mineral is absorbed, transported, stored, and excreted. Describe the deficiency symptoms of trace minerals. Describe the toxicity symptoms from the excess consumption of certain trace minerals. Describe the development of cancer and the effect of genetic, environmental, and dietary factors on the risk of developing cancer. Teaching Strategies, Activities, Demonstrations, and Assignments Assign students the Take Action activity, “Iron and Zinc Intake in a Sample Vegan Diet.” Assign students the Take Action activity, “Is Your Local Water Supply Fluoridated?” Have students visit a local pharmacy to investigate the mineral content of supplements. Select 10 multiple vitamin/mineral supplements. Be sure to include at least two generic brands. List the brand name, contents, measure, and percentage of USRDA. For example, One A Day: Vitamin C, 60 mg, 100% of USRDA. Have students compile the information and make into a handout for the class. Discuss which brands would be wise choices if one were looking for a vitamin/mineral supplement. Are any products available in which all minerals provide less than 150% of the USRDA? Have students visit a local pharmacy and select 10 products sold as iron supplements: five for use with infants or children, four for adults, and one prenatal vitamin. The pharmacist will have to assist the student with prenatal vitamin information. Determine the source and amount of iron in these products, as well as cost per daily dosage. Have students visit a supermarket to look at the breakfast cereals to find the one highest in iron and fiber and lowest in sugar. Compare their findings. Rank cereals from most nutrient dense to least. Use this as a springboard to discuss iron sources. Have students write the name of each mineral on an index card. On the back, they will list one to three key functions of that mineral; food sources; deficiency name, if appropriate; deficiency symptoms; and toxicity symptoms. Have students study these index cards in pairs until they can recall the information about each mineral. Before class, write the name of each mineral on a piece of paper, index card, or "post-it." If you use paper or an index card, remember to take stick pins or tape to class to fasten the card/paper on students' backs. Secure one card/paper/post-it on the back of each student. Have students circulate throughout the room asking other student’s questions about the mineral posted on their back. Only yes and no questions are permitted, for example, "Am I involved in red blood cell formation?" and "Are spinach, oysters, and liver good sources of me?" Only two questions can be asked of any person. After asking two questions of a person, students must move to someone else. Continue the game until everyone correctly identifies the mineral they are. Post lists of foods around the room. Have students determine the key mineral(s) present in each group of foods. Place posters with names of vitamins and minerals around the room. Give students index cards describing symptoms of deficiencies and excesses. Have them match symptom cards with the appropriate vitamin or mineral. Have students complete the Take Action “Iron and Zinc Intake in a Sample Vegan”. Use this as a lead in to discuss the nutritional difficulties of a vegan diet and ways to overcome potential nutritional deficiencies. Lecture Outline Iron (Fe) General Worldwide, 1 in 4 people has anemia Iron deficiency is considered one of the greatest global health risks by WHO Iron in foods Heme iron: iron that is part of hemoglobin and myoglobin, found in animal flesh Beef Pork Seafood Poultry Non-heme iron: found in animal flesh and plant foods Animal products Vegetables (spinach and other leafy greens) Legumes Grains (enriched in refined flours) Supplements Bioavailability of iron from animal sources is higher than from plant foods Leaching of iron into foods from iron cookware contributes to iron intake, especially with acidic foods Iron needs RDA (assumes ~18% absorption efficiency from typical Westernized diet) Adult women up to age 51: 18 mg Adult women after age 51: 8 mg Adult men: 8 mg DV: 18 mg Average intake: 6 mg/1000 kcal 17 mg for men 12 mg for women Absorption, Transport, Storage, and Excretion of Iron Absorption Carrier-mediated transport into small intestinal brush border membrane Ferritin: iron-binding protein produced in enterocytes and other tissues, binds and stores mucosal iron, prevents it from entering the bloodstream When iron stores are low, ferritin production is low to allow iron into bloodstream When iron stores are high, ferritin production is high to keep iron in mucosal iron pool Mucosal block: much stored iron (bound to ferritin) is excreted when enterocytes are sloughed, prevents excess accumulation of iron Transport When needs are high, absorbed iron is released into an intestinal iron pool Iron is transported from enterocytes to interstitial fluid by ferroportin for distribution to body cells Copper-containing enzyme (hephaestin in enterocytes or ceruloplasmin in blood) oxidizes iron from ferrous (Fe2+) to ferric (Fe3+) forms for transport Ferric iron is bound to transferrin for transport to body cells Hemoglobin in blood Storage All cells have transferrin receptors on surface membranes Uptake of iron by cells is regulated by cellular synthesis of transferrin receptors Iron is engulfed by endocytosis and released from transferrin and receptor inside lysosomes and receptor returns to the cell surface Iron is used for cellular functions or stored as ferritin or hemosiderin Very little free iron is found in the body because high reactivity leads to production of free radicals that damage DNA and cell membranes Hemoglobin Myoglobin Excretion Body has limited ability to excrete iron, so absorption, cellular uptake, and storage are tightly regulated Hepcidin aids in regulation of iron balance Increases degradation of ferroportin, which in turn leads to a decrease in the release of iron from enterocytes to body cells Only 10% of body iron is excreted via bile and lost in feces Factors Affecting Iron Absorption Dependent on iron needs, stores, and diet composition When iron stores are adequate, about 14-18% of dietary iron is absorbed Factors that increase iron absorption Increased requirements (35-40% efficiency when iron status is low) Meat factor protein (MFP) Heme form (in ferrous form) Vitamin C and other organic acids increase absorption of non-heme iron by keeping iron in ferrous form Gastric acid reduces ferric iron to ferrous form Factors that decrease iron absorption Decreased requirements (5% efficiency when iron needs are low and stores are saturated) Phytic acid in whole grains and legumes Oxalic acid in leafy green vegetables High fiber intake Polyphenols (e.g., tannins found in tea) Excessive intakes of zinc, manganese, and calcium Functions of Iron Participates in oxidation/reduction reactions Component of hemoglobin Carries oxygen in the blood from lungs to body tissues Carries CO2 to lungs for excretion Synthesis in bone marrow in response to erythropoietin Increased hemoglobin production increases iron requirements Component of myoglobin: protein that transports oxygen from RBCs to muscle cells Energy metabolism Drug and alcohol metabolism Excretion of organic compounds Component of cytochromes in electron transport chain Required for first step in citric acid cycle Synthesis of neurotransmitters, essential for normal early cognitive development and lifelong brain function Immune function: production of lymphocyte cells and natural killer cells Iron Deficiency Most widespread nutritional deficiency in the U.S. Early stages: stores are still available Compromised immune function Decreased work capacity Iron-deficiency anemia: stores become depleted Low hemoglobin synthesis, impaired oxygen transport in blood Fatigue Decreased work capacity Compromised immune function Impaired energy metabolism Delayed cognitive development Diagnosis RBCs: small (microcytic), pale (hypochromic) Hematocrit: percent of total blood volume comprised of RBCs Hemoglobin RBCs, hematocrit, and hemoglobin are not sensitive measures of iron status because they are unchanged in early stages of deficiency and are affected by disease, inflammation, blood loss, other nutrient deficiencies Transferrin receptor number reflects cellular iron need and is unaffected by other conditions High-risk populations Premature infants: iron stores are deposited near end of pregnancy Young children: rapid growth, low dietary intake Teenage girls and women of childbearing age: menstrual losses and insufficient dietary intake Pregnant women Vegetarians Frequent blood donors: 1 pint = 200- 250 mg Fe Iron Overload and Toxicity UL: 45 mg Consequences Nausea/vomiting Stomach irritation Diarrhea Impaired absorption of other trace minerals Accidental iron overdose is leading cause of accidental poisoning in children under age 6 In adults, iron toxicity results from hemochromatosis: genetic condition in which mucosal block is ineffective Deficiency of hepcidin, which prevents the normal degradation cycle of ferroportin, absorption and transport of iron across enterocyte are high With lack of excretion mechanism for excess iron, iron accumulates and causes tissue injury (e.g., iron deposits in liver, heart, and other organs) High-risk populations Hemochromatosis Excessive supplementation Frequent blood transfusions Treatment Decrease supplemental intake Periodic blood removal Administration of chelator that binds iron and increases its excretion (also binds other trace minerals) Zinc (Zn) Zinc in Foods Animal-based foods Beef Lamb Pork Seafood Plant-based foods Nuts Beans Wheat germ Whole grains (if leavened) Fortified breakfast cereal Phytic acid in wheat products may decrease zinc bioavailability, but yeast fermentation frees zinc Dietary Needs for Zinc RDA Adult men: 11 mg Adult women: 8 mg DV: 15 mg Average intake meets RDA Absorption, Transport, Storage, and Excretion of Zinc Absorption Simple diffusion and active transport in the small intestine Upon absorption into intestinal cells, zinc induces synthesis of cysteine-rich intestinal protein (CRIP) and metallothionein, which bind to zinc and traps it within intestinal cells Mucosal block: if not absorbed, zinc will be excreted with sloughed intestinal cells Large doses of zinc can override mucosal block Factors that increase zinc absorption Increased body needs High intake of animal protein Factors that decrease zinc absorption Excessive intake of zinc or non-heme iron Excessive intake of fiber and phytic acid Adequate zinc status Transport Binds to blood proteins (e.g., albumin) for transport to liver Liver repackages zinc for export bound to alpha-2-macroglobulin, albumin, and other proteins Storage No storage site Exchangeable pool of zinc in liver, bone, pancreas, kidney, and blood Excretion Feces Urine Sweat Functions of Zinc Required by 300 enzymes DNA and RNA synthesis Heme synthesis Bone formation Taste acuity Immune function Reproduction Growth and development Antioxidant defenses (superoxide dismutase) Stabilizes structures of cell membrane proteins Stabilizes gene transcription fingers (“zinc fingers”) Stabilizes receptor proteins for vitamin A, vitamin D, and thyroid hormone May shorten duration of common cold, but evidence on supplementation is not conclusive Zinc Deficiency Consequences Loss of appetite Delayed growth Delayed sexual maturation Dermatitis Impaired vitamin A function Alopecia Decreased taste sensitivity Poor wound healing Immune dysfunction Severe diarrhea Birth defects Infant mortality High-risk populations Young children Malabsorptive diseases Kidney dialysis Low intake of animal-based foods Acrodermatitis enteropathica: genetic condition that impairs intestinal absorption Marginal zinc deficiencies are difficult to detect due to lack of assessment methods Zinc Toxicity UL: 40 mg Consequences Loss of appetite Nausea/vomiting Intestinal cramps Diarrhea Impaired immune function Reduced copper absorption and activity of copper-containing enzymes Copper (Cu) Copper in Foods Liver Shellfish Nuts Seeds Lentils Soy products Dark chocolate Dried fruits Whole grain products Some tap water sources Meat protein may promote copper absorption Dietary Needs for Copper RDA: 900 µg DV: 2 mg Average adult intake: 1000 - 1600 µg/day Absorption, Transport, Storage, and Excretion of Copper Absorption Simple diffusion and active transport into mucosal cells Primary regulation for copper balance Efficiency may vary from 12 - 70% Highest efficiency when intake is low Lowest efficiency with excessive intakes of copper, iron, or zinc. Also low with high intake of phytate from cereals and legumes Transport In bloodstream, bound to albumin and other proteins for transport to liver From the liver, copper is bound to ceruloplasmin for transport to other tissues In tissue, copper binds to specific receptors that release the mineral to intracellular transporters Storage Very little storage Liver is main storage site Excess copper binds to intestinal metallothionein Excretion of Copper: bile Functions of Copper Component of many enzymes due to ability to alternate between 2 oxidation states (Cu1+ and Cu2+) Ceruloplasmin (ferroxidase I) oxidizes ferrous to ferric iron for incorporation into transferrin; copper deficiency can lead to development of anemia Ceruloplasmin also increases during inflammation and infection, thereby preventing damage to body cells Superoxide dismutase: antioxidant enzyme system that eliminates superoxide free radicals Cytochrome C oxidase: catalyzes last step in electron transport chain Monoamine oxidase: regulates neurotransmitters Lysyl oxidase: connective tissue formation Copper Deficiency Rare High-risk populations Premature infants fed milk-based formulas Infants recovering from malnutrition Long-term TPN without added copper Individuals consuming excessive amounts of zinc Menkes disease Consequences Anemia Decreased WBC counts (leukopenia) Skeletal abnormalities (osteopenia) Loss of skin and hair pigmentation Cardiovascular changes Impaired immune function May increase risk of neurological disorders (e.g., Lou Gehrig’s disease and Alzheimer’s disease) Marginal intakes may lead to weakened immune function, glucose intolerance, elevated cholesterol, and cardiac abnormalities Determining marginal copper deficiency is difficult due to lack of reliable indicators Copper Toxicity Not common Potential causes Accidental overdoses among children Consumption of copper-contaminated food or water Wilson’s disease: genetic disorder of excess copper storage Consequences Abdominal pain Nausea/vomiting Diarrhea Cirrhosis Neurological damage UL: 10 mg Manganese (Mn) Manganese in Foods Whole grain cereals Nuts Legumes Leafy greens Tea Dietary Needs for Manganese AI Adult men: 2.3 mg Adult women: 1.8 mg DV: 2 mg Average intake: 2 - 6 mg/day Absorption, Transport, Storage, and Excretion of Manganese Absorption Simple diffusion and active transport in the small intestine Absorption efficiency is ~10%, affected by dietary intake and iron status High absorption efficiency with low manganese intake and iron deficiency Decreased absorption with high intakes of manganese and possibly copper, non-heme iron, phytates and oxalates Transport: bound to alpha-2-macroglobulin for transport to liver and then via transferrin, alpha-2- macroglobulin, and albumin to other tissues Storage: bone (possibly) Excretion Bile Primary regulation of manganese Functions of Manganese Cofactor for many enzymes due to ability to alternate between oxidation states (Mn2+ and Mn3+) Carbohydrate metabolism Gluconeogenesis Collagen formation Antioxidant defense (Mn superoxide dismutase) Manganese Deficiency and Toxicity Deficiency is not well documented in humans Consequences Nausea and vomiting Poor growth Skeletal abnormalities Impaired carbohydrate and lipid metabolism Abnormal reproductive function Toxicity Consequences Severe neurological impairment Similar to Parkinson’s disease (muscle stiffness, tremors) Potential causes Children receiving long-term TPN Inhalation of airborne industrial and automotive emissions UL: 11 mg Iodine (I) General Present in food as iodide (I-) and other non-elemental forms Heaviest element needed for human health Responsible for thyroid hormone synthesis Iodine in Foods Natural content of most foods is low Saltwater seafood Seaweed Iodized salt Dairy products (added to cattle feed and sanitizing solutions used on dairy equipment) Breads and cereals (if prepared with iodized salt and/or dough conditioners) Plant foods (if soil is rich in iodine; usually in coastal regions) Bioavailability and use by thyroid gland are affected by goitrogens in raw vegetables (e.g., turnips, cabbage, Brussels sprouts, cauliflower, broccoli, rutabagas, potatoes, and cassava), peanuts, soy, peaches, and strawberries; activity of goitrogens is decreased by cooking Dietary Needs for Iodine RDA: 150 µg DV: 150 µg Average intake: 190 - 300 µg, not accounting for iodized salt used at the table Absorption, Transport, Storage, and Excretion of Iodine Absorption: iodide and iodates are efficiently absorbed in the small intestine Transport: thyroxine Storage: thyroid gland, used to support thyroid hormone synthesis Excretion: urine Functions of Iodine Essential component of thyroxine (T4) and triiodothyronine (T3) Transported as T4, converted toT3 (active form) in body cells by deiodinase enzymes, all of which require selenium Functions of thyroid hormones Regulation of basal energy expenditure Macronutrient metabolism Brain and nervous system development Overall growth Iodine Deficiency Disorders (IDD) Endemic: habitual presence of a disease within a given geographic area Goiter With lack of iodine, plasma T4 drops, causing secretion of thyroid-stimulating hormone (TSH) TSH leads to enlargement of thyroid gland, allowing temporary maintenance of thyroid hormone synthesis Goiter is not harmful, but may put pressure on esophagus and trachea Iodine deficiency during pregnancy may lead to problems in offspring Congenital abnormalities Low birth weight Cretinism Severe mental retardation Loss of hearing and speech abilities Short stature Muscle spasticity Death 1/3 of world population is at risk of iodine deficiency, particularly in South America, Asia, Africa, and Middle East Although fortification of table salt with iodine is effective at eradicating goiter, many countries have not yet adopted the practice WHO calls iodine deficiency the “greatest single cause of preventable brain damage and mental retardation” Iodine Toxicity UL: 1100 µg Consequences Enlargement of thyroid gland Decreased thyroid hormone synthesis Excess iodine intakes may also increase the risk of Hyperthyroidism Autoimmune thyroid disease Thyroid cancer Potential causes High consumption of iodine-rich seaweed High levels of environmental iodine Increased use of iodine in water purification Excessive fortification of salt Selenium (Se) Selenium in Foods Varies depending on soil content where plant or animal was grown/raised Seafood Meats Cereals Grains Dietary Needs for Selenium RDA: 55 µg DV: 70 µg Average intakes exceed the RDA Absorption, Transport, Storage, and Excretion of Selenium Absorption Most selenium in foods is bound to methionine (selenomethionine) and cysteine (selenocysteine) Selenomethionine and selenocysteine are well absorbed in the small intestine Absorption efficiency: 50 - 100% of dietary intake Absorption is not affected by selenium status Absorption is not responsible for regulating selenium homeostasis Transport: little is known Storage Liver Pancreas Muscle Kidneys Thyroid Selenomethionine is storage pool Selenocysteine is biologically active form Excretion Urine Primary means of regulating selenium homeostasis Functions of Selenium Component of at least 25 enzymes and proteins Antioxidant defenses, spares vitamin E for use in other antioxidant functions Glutathione peroxidase (GPX) enzymes Thioredoxin reductase enzymes Selenoprotein P Thyroid metabolism: iodothyronine deiodinase converts T4 to T3 Immune function; may inactivate a virus linked to the development of Keshan disease May decrease risk of prostate, lung, or other cancers Selenium Deficiency No specific deficiency disease Consequences Changes in thyroid metabolism Possible increased risk of certain cancers Development of Keshan disease (insufficient cardiac function) Selenium Toxicity Potential causes: excess supplementation Consequences Nausea Diarrhea Fatigue Hair loss Changes in nails Impairment of sulfur and protein metabolism UL: 400 µg Chromium (Cr) Chromium in Foods Nutrient content information is lacking, so nutrient databases are incomplete Meats Liver Eggs Whole-grain products Broccoli Mushrooms Dried beans Nuts Dark chocolate Because chromium is used to manufacture steel, small amounts of the mineral are transferred to food by processing Dietary Needs for Chromium AI Adult men (19 - 50 years): 35 µg Adult women (19 - 50 years): 25 µg Adult men (50+years): 30 µg Adult women (50+ years): 20 µg DV: 120 µg Average intake generally meets AI Absorption, Transport, Storage, and Excretion of Chromium Absorption efficiency is very low, but appears to increase when intakes are low and when consumed with vitamin C Likely that phytates in whole grains decrease absorption Bioavailability is difficult to assess Transport: transferrin Storage Bones Liver Kidneys Spleen Excretion: most dietary chromium is excreted in feces Functions of Chromium Not fully known May enhance insulin action, promote glucose uptake into cells, and normalize blood sugar levels; supplementation for type 2 diabetes has not proven effective Used to enhance muscle mass and strength among athletes; evidence for effectiveness is poor Chromium Deficiency and Toxicity Deficiency Lack of sensitive indicators of chromium status Potential causes: TPN that lacks chromium Consequences Weight loss Glucose intolerance Nerve damage Toxicity No UL High doses of chromium supplements are cause for concern Fluoride (F) General May not be essential nutrient because all basic body functions can occur without it Link between fluoride content of water and prevention of dental caries led to controlled water fluoridation in some areas Controversy exists over fluoridation of public water supply; some argue that excess exposure is a concern Fluoride in Foods Fluoridated water (0.7 ppm or 0.7 mg/L); not all public or private water sources are fluoridated Tea Seafood Seaweed Fluoridated toothpastes, mouth rinses, and dental treatments Dietary Needs for Fluoride AI Adult women: 3 mg Adult men: 4 mg Infants up to 6 months: 0.01 mg Infants 6 - 12 months: 0.5 mg Children and adolescents: 0.7 - 3 mg Absorption, Transport, Storage, and Excretion of Fluoride Absorption Passive diffusion in stomach and small intestine Absorption efficiency: 80 - 90% Transport: through bloodstream Storage (most storage occurs during infancy, childhood, and adolescence) Teeth Skeleton Excretion: urine Functions of Fluoride Supports deposition of calcium and phosphorus in teeth and bones Protection against dental caries Hydroxyfluoroapatite crystals are resistant to bacteria and acids in the mouth Remineralization of enamel lesions Reduces net loss of minerals from tooth enamel Fluoride Deficiency and Toxicity Deficiencies Consequences Increased risk of dental caries No specific deficiency disease Toxicity Consequences Nausea/vomiting Diarrhea Sweating Spasms Convulsions Coma Mottling (fluorosis) of tooth enamel UL: For infants and children up to 8 years: 0.1 mg/kg body weight/day For children older than 8 years and adults: 10 mg/day Molybdenum (Mo) and Ultratrace Minerals Ultratrace minerals: daily requirements are low, but vital for health Molybdenum Functions: enzyme cofactor Food sources Amount of Mo varies depending on soil content Grains Legumes Nuts Dietary requirements RDA: 45 µg DV: 75 µg Average intakes meet or exceed RDA Deficiencies and toxicities are rare, but UL: 2000 µg Other ultratrace minerals with incomplete data on needs and functions Arsenic Functions Amino acid metabolism DNA function Requirements Estimated needs: 12 -25 µg UL: none set Average intake: 30 µg Dietary sources Fish Grains Cereals Boron Functions: Ion transport across cell membranes Steroid hormone metabolism Requirements Estimated needs: 1 - 13mg UL: 20 mg Average intake: 0.75 - 1.35 mg Dietary sources Legumes Fruits Vegetables Potatoes Wine Nickel Functions Metabolism of amino acids Metabolism of fatty acids Metabolism of vitamin B-12 Metabolism of folic acid Requirements Estimated needs: 25 - 35 µg UL: 1 mg Average intake: 69 - 162 µg Dietary sources Chocolate Nuts Legumes Whole grains Silicon Functions: bone formation Requirements Estimated needs: 35 - 40 µg UL: none set Average intake: 19 - 40 µg Dietary sources Root vegetables Whole grains Vanadium Functions: mimics insulin action Requirements Estimated needs: 10 µg UL: 1.8 mg Average intake: 6 - 18 µg Dietary sources Shellfish Mushrooms Parsley Dill Global Perspective: The e-Library of Evidence for Nutrition Action Malnutrition affects several billion people worldwide Underweight and overweight are linked to serious health problems Underweight, combined with suboptimal breastfeeding and micronutrient deficiencies causes the illness and death of 7% of the population In children under 5 years, this rate is raised to 35% of death Iodine deficiency is a preventable cause of brain damage Iron deficiency contributes to the health risks of low-birth-weight babies Zinc and vitamin A deficiencies result in increased risk for infections and death in children Overweight children and adults have increased risk of developing Cardiovascular disease Diabetes Cancer The WHO has launched eLENA in 2011 Provides easily accessed, evidence-based information to help launch successful nutrition interventions Interventions of eLENA include Promoting breastfeeding Fortification of staple foods with iron, zinc, vitamin A, folic acid, and/or vitamin B-12 Iron and folic acid supplementation for pregnant women Iodine fortification Vitamin A supplementation for infants and children Reduction of impact of marketing of foods and beverages high in fat, sugar, and/or salt Clinical Perspective: Nutrients, Diet, and Cancer What is Cancer? Variety of diseases that affect a variety of tissues, but all forms are united by the abnormal and uncontrolled division of altered cells Benign tumors are non-cancerous; enclosed in a membrane that prevents them from spreading; only harmful if they interfere with normal function Malignant tumors: capable of invading surrounding structures and spreading to other parts of the body (metastasis) Types of tumors Carcinomas: 80 - 90% of all cancers; develop from epithelial cells; affect secretory organs Sarcomas: affect connective tissues (e.g., bone) Lymphomas: malignant tumors in lymph nodes and lymphoid tissues Leukemias: cancers of precursor WBCs in bone marrow Development of Cancer (carcinogenesis) In normal cells: Cell replication is regulated by proto-oncogenes Tumor suppressor cells prevent uncontrolled growth Repair mechanisms look for and correct errors in DNA In cancer, oncogenes promote unregulated cell replication Carcinogenesis Initiation (relatively short stage; minutes to days; spontaneous, exposure of cells to carcinogen) Promotion (may take months to years, mutation is locked into DNA, promoters encourage uncontrolled replication of altered DNA) Progression (cells grow autonomously, proliferate, invade surrounding tissue, metastasize to other sites, may be stopped if immune system destroys cancerous cells or if cancerous cells are so defective, they cannot grow) Genetic, Environmental, and Dietary Factors Genetic factors account for 5% of cancer incidence Environmental factors play a large role Exposure to carcinogens Lack of physical activity Obesity Diet Dietary factors that influence cancer risk Diets low in fruits and vegetables are associated with increased risk for certain cancers Excessive energy intake and obesity increase risk of breast cancer, likely due to increased production of estrogen and insulin and availability of excess energy to support tumor growth High intakes of meats, especially red meat and grilled meat, increase risk of colorectal, kidney, pancreatic, and stomach cancers, likely due to saturated fat content, polyaromatic hydrocarbons, or nitrosamine compounds Fried foods may increase cancer risk due to high calorie and fat content, as well as presence of acrylamide (produced when starches are fried at high temperatures) Whole grains and fiber intakes are associated with a decreased risk of colorectal cancer and improved weight control Excess alcohol intake risk of mouth, throat, esophagus, breast, colon, and liver cancer Adequate intakes of calcium and vitamin D may decrease risk of colorectal cancer Calcium may bind free fatty acids and bile acids to prevent them from reacting with potential cancer cells Vitamin D may inhibit progression of cancer growth from malignant polyps Diet and Health Guidelines for Cancer Prevention Choose a diet rich in a variety of plant-based foods Eat plenty of vegetables and fruits Maintain a healthy weight and be physically active Drink alcohol only in moderation, if at all Select foods low in fat and salt Prepare and store foods safely Avoid tobacco Chapter 16 Nutritional Aspects of Pregnancy and Breastfeeding Overview Chapter 16 provides a detailed look at the impact of nutrition on successful pregnancy and breastfeeding. The physiological changes of pregnancy, stages of fetal growth and development, and process of producing and releasing breast milk are examined. Proper nutrition throughout pregnancy and lactation aims to prevent preterm birth, low birth weight, and small-for-gestational-age births and to promote normal infant growth while preserving maternal health. Calorie and nutrient needs generally increase during pregnancy and lactation. Specific nutrients of concern include protein, essential fatty acids, calcium, iron, zinc, iodine, vitamin B-6, vitamin B-12, and vitamin D. The benefits of moderate physical activity during pregnancy are discussed. Students will learn how to use a balanced, varied diet based on MyPlate, including some fortified foods and a multivitamin and mineral supplement, to achieve optimal health for mother and infant during pregnancy and lactation. Learning Outcomes Describe the factors that predict a successful pregnancy outcome. List major physiological changes that occur in the body during pregnancy and describe how nutrient needs are altered. Specify the optimal weight gain during pregnancy for adult women. Describe the special nutritional needs of pregnant and lactating women, summarize factors that put them at risk for nutrient deficiencies, and plan a nutritious diet for them. Identify nutrients that often need to be supplemented during pregnancy and lactation and explain the reason for each. Discuss potential nutrition-related problems that occur during pregnancy and suggest techniques for coping with these problems. List substances and practices to avoid during pregnancy and lactation and describe why they are harmful. Describe the physiological process of breastfeeding. Teaching Strategies, Activities, Demonstrations, and Assignments 1. Assign students the Take Action activity, “Healthy Diets for Pregnant Women.” 2. Assign students the Take Action activity at the end of the chapter, “Investigating Breastfeeding.” 3. Give students a sample "typical" diet consumed by a pregnant woman along with a list of her food preferences. Ask the student to make a list of recommendations that would be appropriate to make the diet meet nutritional recommendations within the energy allowance. Next, the student should list recommendations that should be given to modify her diet for breastfeeding. Have students use guidelines given in the chapter to evaluate the diet. 4. Have students visit a local pharmacy and record the nutrient composition and cost of prenatal supplements they find there. Another group of students could use the PDR to determine the content of prescription supplements. Cost could be obtained by contacting the pharmacy. Use this as a springboard for class discussion about prenatal supplements. Students should answer questions such as: "Are prescription or over-the-counter supplements more expensive?", "Do they contain more nutrients than are needed?", "Do they provide amounts of iron and folate suggested in the chapter?" 5. Have students plan a nutritionally adequate one-day menu for a pregnant woman who is a vegan. Would supplements be required? If so, what ones? Have them use guidelines given in the chapter. 6. Ask an expert from the local community or someone from an organization like the La Leche League to lead a discussion about breastfeeding, and its advantages and disadvantages. 7. Have a class debate on advantages and disadvantages of breastfeeding. Have two groups of volunteers research the topic and have an in-class debate. 8. Ask students to interview their mothers to find out how much the student weighed at birth, where they were born, were they bottle-fed or breastfed, when were solid foods introduced, etc. Have a class discussion comparing current infant feeding standards with the standards when they were infants. Lecture Outline Pregnancy General Gestation: conception to birth, usually 40 weeks Favorable pregnancy outcome Live, healthy infant Full-term gestation period (longer than 39 to 40 weeks) Infant weighs more than 5.5 pounds Permits the mother to return to her prepregnancy status Preterm birth: before 37 weeks gestation Low birth weight: weighing less than 5.5 pounds (2500 g) Small for gestational age: infants suffering from prenatal growth retardation, weigh less than expected for gestational age Average weight of a healthy, full-term infant: 7.5 pounds Complications associated with preterm birth, low birth weight, and/or prenatal growth retardation Increased risk of infant death Medical complications Handicaps Illnesses Temperature regulation Growth Development Nutritional complications Poor blood glucose control Increased nutrient and calorie needs Risk of nutrient deficiencies - many nutrient stores are deposited during last 4 - 6 weeks of gestation At risk of developing more body fat and less lean mass during childhood Prenatal Developmental Stages: Conception, Zygotic, Embryonic, and Fetal Conception: sperm unites with ovum Zygotic stage: 30 hours after conception - 2 weeks after conception Fertilized egg implants in uterine lining Embryonic stage: 2 weeks after conception - 8 weeks after conception Cells have separated into 3 thin layers that develop into body systems Endoderm: digestive system, liver, and pancreas Mesoderm: skeleton, muscles, heart, and blood vessels Ectoderm: skin, nervous system, and sensory organs By the end of the embryonic stage, the embryo is complex (e.g., major organs are in place and some have started to function), but only the size of a pea Fetal period: 9 weeks after conception - birth 90% of all fetal growth occurs during last 20 weeks of gestation Average length at birth: 20 - 22 inches Average weight at birth: 7 - 8 pounds Body fat is deposited subcutaneously (about 16% by 38 weeks) to help regulate body temperature Trimesters: three 13 -14 week periods into which pregnancy is arbitrarily divided Critical Periods: finite window of opportunity for cells to develop in a particular organ or tissue (see Figure 16-4) Most occur during first trimester Nutrient deficiencies, nutrient excesses, pathogens, trauma, radiation, tobacco smoke, and toxins can interfere with normal development, resulting in abnormalities or spontaneous abortion Detrimental prenatal environment can adversely affect development at any stage of development, but damage is most catastrophic during critical periods Some nutrient deficits can be partly reversed by adequate nutrition after birth Spontaneous abortion: naturally occurring premature termination of pregnancy prior to 20 weeks of gestation Early spontaneous abortions (i.e., miscarriages) usually result from genetic defect or fatal error in fetal development Half or more of all pregnancies end in miscarriages, sometimes before woman knows she is pregnant 15 - 20% more pregnancies end before normal delivery (after 20 weeks gestation) Nourishing the Zygote, Embryo, and Fetus Zygote Absorbs secretions from uterine glands Digests some of uterine lining Embryo Placenta delivers nourishment to developing organism through umbilical cord, which contains 2 arteries and 1 vein to transfer nutrients, oxygen, and wastes to/from maternal blood supply Maternal and fetal blood supplies do not mix, but nutrients, oxygen, and wastes are exchanged by absorption mechanisms similar to GI tract Placenta synthesizes fatty acids, cholesterol, and glycogen Placenta produces hormones that regulate fetal metabolism and physiological changes that support pregnancy in the mother Placenta grows throughout pregnancy (to 1.5 pounds at birth) Placenta’s size and ability to support optimal fetal growth depend on mother’s nutritional status Nutrient Needs of Pregnant Women General Mother needs to consume more nutrient-dense foods More efficient use of some nutrients (e.g., protein) Better absorption of some nutrients (e.g., calcium, iron) Decreased excretion of some nutrients (e.g., zinc, riboflavin) Energy Needs Extra calories support growth of maternal and fetal tissues and extra workload on mother’s heart, lungs, and other organs Calorie needs First trimester: few extra calories above prepregnancy needs Second trimester: 350 extra calories above prepregnancy needs Third trimester: 450 extra calories above prepregnancy needs Estimates of additional calorie needs may vary Prepregnancy weight Maternal age Physical activity level Consequences of calorie restriction during pregnancy Small for gestational age Infant mortality Thrifty metabolism in offspring, which elevates risk of obesity and type 2 diabetes Greater risk of heart disease, high blood cholesterol, diabetes, high blood pressure, and impaired immune function in offspring Iodine Ensures adequate production of thyroid hormone Thyroid deficiency during pregnancy can lead to cretinism or other serious birth defects Use of iodized salt can prevent deficiency Nutrients Needed for Building New Cells Protein More than 50% above needs of non-pregnant women In U.S. and Canada, protein intake is plentiful Protein supplements are unnecessary and not recommended Essential fatty acids Required for normal fetal growth and development, particularly of brain and eyes Sufficient EFAs, particularly DHA, may improve gestation duration and infant birth weight, length, and head circumference Many women need to decrease the ratio of n-6:n-3 fatty acids Minimize trans fatty acid intake during pregnancy Zinc Intake of pregnant and non-pregnant women is often low, but deficiencies are uncommon Consequences of severe zinc deficiency Birth defects Fetal growth retardation Premature birth Spontaneous abortion Prolonged labor Maternal bleeding Maternal infections Pregnancy-induced hypertension/preeclampsia Potential causes Low dietary zinc intake High fiber intake High iron intake Factors that impair transfer of zinc from placenta to fetus Use of certain medications Cigarette smoking Alcohol abuse Strenuous exercise Folate and vitamin B-12 Roles during pregnancy DNA synthesis Cell formation (e.g., RBCs) Consequences of deficiency Anemia Premature birth Low birth weight Fetal growth retardation Poor placenta development Neural tube defects Spontaneous abortion Heart defects (1 in 110 newborns) Autism Neural tube defects (see Figure 16-6) Neural tube develops into brain and spinal cord Spina bifida results from incomplete closure of tube during early gestation; leads to spinal defects, dislocated hips, or other handicaps Anencephaly results from poor brain formation; leads to infant death In addition to eating a folate-rich diet, use of multivitamin and mineral supplement is advised before becoming pregnant to ensure adequate folate status History of NTDs may necessitate folic acid supplementation in excess of RDA; consult health care provider to prevent masking a B-12 deficiency Insufficient intake of choline and/or vitamin B-12 may also contribute to the development of NTD Vegans need a vitamin B-12 supplement Folic acid (form in supplements and fortified foods) is absorbed twice as well as folate that naturally occurs in foods Fortification of grains with folate has led to17% reduction in NTDs since 1998 Iron Needs rise significantly during pregnancy Roles of iron during pregnancy RBC formation (increased maternal supply) Many women consume insufficient iron and have poor iron status prior to conception Maternal adaptations to conserve iron Absorption increased up to 3 times during pregnancy Menstruation ceases Supplementation Many experts advise 30 mg/day May decrease absorption of zinc and copper May decrease appetite May cause nausea or constipation Avoid coffee or tea with supplements to limit polyphenols, which hinder absorption Eat foods rich in vitamin C or heme iron with iron supplements to enhance absorption Consequences of deficiency during pregnancy Suboptimal delivery of oxygen to fetus Low birth weight Premature birth Infant death due to low infant iron stores Preeclampsia Labor and delivery complications Increased risk of maternal death Anemia of pregnancy: normal decrease in ratio of RBCs to total blood volume due to hemodilution (physiological anemia) RBCs increase 20 - 30%, whereas blood volume increases 50% No danger to health of mother or fetus Nutrients Needed for Bone and Tooth Development Calcium AI does not increase during pregnancy because maternal absorption efficiency increases Failure to meet AI puts mother at risk for osteoporosis later in life because calcium for fetal development is drawn from mother’s bones regardless of her intake Populations at risk for calcium deficiency Vegans Pregnant teens Women at risk of pregnancy-induced hypertension Avoidance of dairy products Supplementation may be necessary Vitamin D Consequences of deficiency for mother Osteopenia Consequences of deficiency for fetus Rickets Poor growth Inadequate calcification of bones and teeth Populations at risk for vitamin D deficiency Avoidance of milk Limited exposure to sunlight Supplementation may be necessary, particularly during winter months in northern latitudes Pregnant Women Do Not Have an Instinctive Drive to Consume More Nutrients Cravings and food aversions are likely due to hormonal changes or family traditions; no evidence that they result from nutrient deficiencies Cravings and aversions won’t affect nutrient status as long as overall diet provides adequate nutrients and calories To cope with cravings, eat small amounts of desired foods with regular meals or snacks; avoid limiting dietary variety Pica: eating non-food substances (e.g., laundry starch, coal, clay, rubber) Occurs among men and women in many racial and ethnic groups Seems to be more of a family tradition than an internal drive Dangers outweigh potential benefits Ingestion of toxins Intestinal blockages Parasites and pathogens Malnutrition Obesity Premature birth Low birth weight Poor fetal nutrient stores Maternal and fetal death Expert Perspective: Grains and Folic Acid Fortification Research demonstrating positive effect of folic acid supplementation on rate of NTDs led Public Health Service to recommend 400 µg folic acid for all women of childbearing age Exact mechanism for connection between folic acid and NTDs is not known, but developing neural tissue has high folate needs DNA synthesis Cell division Normal transformation of amino acids into components that form neural tissue Cell differentiation Causes for poor folate status Low dietary intake Genetic condition that causes inefficient use of folic acid FDA mandated fortification of grains in 1998 2 slices of enriched bread provide over 10% of RDA Whole grains are not fortified; slice of bread provides <5% of RDA Breakfast cereals may be fortified up to 100% RDA In addition to consuming fortified foods, March of Dimes recommends multivitamin supplying 400 µg, but only ½ of women take such supplements During pregnancy, folic acid intake should increase to 600 µg Diet and Exercise Plan for Pregnancy General Nutrient needs increase more than energy needs, so food choices must be nutrient dense MyPlate eating plans supports successful pregnancy outcome First trimester 2200 kcal Milk: 3 c Meat and beans: 6 oz.-equivalents Vegetables: 3 c; 1 c should be rich in vitamin C and 1 c should be rich in folate Fruit: 2 c Grains: 7 oz.-equivalents; emphasize whole grains Oils: 6 t vegetable oil, especially to provide EFAs Discretionary calories: up to 300 kcal for weight maintenance Second and third trimesters 2600 kcal Milk: 3 c Meat and beans: 6 ½ oz.-equivalents Vegetables: 3 ½ c Fruit: 2 c Grains: 8 oz.-equivalents Oils: 7 tsp vegetable oil Discretionary calories: up to 400 kcal for gradual weight gain Prenatal Vitamin and Mineral Supplements Routinely prescribed, especially for Women with a history of frequent dieting Teenagers Vegans Women who have a low income Women who are underweight Smokers Abusers of alcohol or illegal drugs Women carrying multiple fetuses Women with restricted dietary variety Over-the-counter or prescription (for high iron or folic acid contents) Megadoses can be detrimental to maternal and fetal health Iron Zinc Selenium Vitamin A (teratogenic above 3000 µg/day) Vitamin B-6 Vitamin C Vitamin D Some physicians only prescribe iron supplements during 2nd and 3rd trimesters and/or individual vitamins or minerals to cover deficiencies (e.g., B-12 for vegans) Physical Activity during Pregnancy Low- or moderate-intensity exercise offers physical and psychological benefits for woman with normal, healthy pregnancy Improved cardiovascular function Easier, less complicated labor Improved attitude and mental state Prevention or treatment of gestational diabetes Infants tend to be leaner and more neurologically mature Contraindications for physical activity during pregnancy Premature labor contractions Consult health-care provider Recommendations for safe exercise program during pregnancy Exercise moderately for ~30 minutes on most days of the week Drink plenty of liquids Keep heart rate below 140 bpm Include cool-down period After 4th month, avoid exercises done while lying down Avoid deep flexing, joint extensions, and jarring activities Stay cool in hot, humid weather Stop exercising immediately if discomfort occurs Avoid strenuous or endurance activities Avoid activities that could cause abdominal trauma, involve rapid shifts in balance or body position, or compress the uterus Avoid becoming overtired Global Perspective: Pregnancy and Malnutrition Effects of undernutrition are profound during pregnancy and fetal life In Africa, women have 1/160 chance of death from pregnancy (compared to 1/3700 in developed countries) Premature birth, low birth weight Reduced lung function Weakened immune system Increased risk of premature death Growth and developmental problems Calorie restriction (e.g., 1000 kcal/day) limits fetal growth and development Famine in Africa Food shortages during WWII in Holland Food shortages during siege of Leningrad Nutrition-Related Factors Affecting Pregnancy Outcome Maternal Prepregnancy Weight Pregnancy complications can result when mother is either underweight or overweight at start of pregnancy Problems associated with high prepregnancy weight Risks for infant Increased risk of birth defects Increased risk of infant death Increased risk of obesity in childhood Risks for mother High blood pressure Gestational diabetes Cesarean delivery Problems associated with low prepregnancy weight Problems are likely due to lighter placenta and decreased maternal nutrient stores (especially iron) Increased risk of low birth weight Increased risk of premature birth Prepregnancy weight and nutrient stores affect fertility Underweight women may experience amenorrhea, which reduces ovulation Obese women also may have difficulty becoming pregnant Additional estrogen produced by extra fat stores and insulin resistance reduce fertility Low nutrient intakes (e.g., zinc, folate, vitamin C) affect sperm production Maternal Weight Gain Maternal weight gain supports fetal and maternal growth and prepares mother’s body for lactation (see Figure 16-7) Maternal fat stores: 4 - 8 lbs. Uterus and breasts: 6 lbs. Blood: 4 lbs. Fetus, placenta, and amniotic fluid: 11 lbs.; fetus weighs about 8 lbs. Recommended weight gain for optimal health of both mother and infant based on prepregnancy BMI (see Table 16-4) Low (BMI 30): 11 - 20 lbs. Shorter women, women from different racial and ethnic groups, and/or teenagers should follow recommendations in Table 16-4 Normal-BMI women carrying twins should gain 37 - 45 lbs. Consequences of gaining too little weight during pregnancy Premature birth Small for gestational age Infant death Consequences of gaining too much weight during pregnancy Large babies Increased delivery complications Infant mortality Postpartum maternal weight retention Pattern of Maternal Weight Gain First trimester: 1.1 – 4.4 lbs., accounting for growth of breasts and uterus Second and third trimesters: 0.8 - 1 lb./week at a slow, steady rate Underweight women should gain 1 – 1.3 lbs./week Overweight women should gain 0.5 – 0.7 lb./week Obese women should gain 0.4 – 0.6 lb./week Low weight gain during 2nd and 3rd trimesters increases chances of fetal growth retardation Low weight gain during the 3rd trimester raises risk of premature birth If weight gain deviates from recommendations, make adjustments to get back on track (e.g., slow rate of weight gain), but don’t try to lose weight while pregnant Sudden weight changes during pregnancy may signal health problem (e.g., pregnancy-induced hypertension) Nutrition-Related Factors Affecting Pregnancy Outcome Young Maternal Age Concerns for teen mothers Physical immaturity: physical maturation continues for 5 years after menarche (average age of menarche is 13 y) Teen years demand high nutrient intake, and supporting nutrient needs of both mother and infant is challenging Underweight at start of pregnancy, gain too little weight during pregnancy Inadequate prenatal care Risks for infants of teen mothers Premature birth Prenatal growth retardation Infant death Stillbirth Spontaneous abortion Maternal Eating Patterns Calorie restriction Ketones are poorly used by fetal brain and may slow its development Women should consume regular meals and avoid fasting more than 12 hours Weight loss should never be attempted during pregnancy Carbohydrate intake should be at least 175 g/day to prevent ketosis Women with eating disorders, diabetes, or phenylketonuria should work with health-care providers to ensure diets meet their own and their baby’s needs Vegan diets: careful planning to ensure adequate protein, vitamin D, vitamin B-6, iron, calcium, zinc, and vitamin B-12 Use of prenatal multivitamin and mineral supplement helps fill micronutrient gaps; avoid taking iron and calcium together Maternal Health Pregnancy History Numerous previous pregnancies, closely spaced pregnancies, and/or multiple births deplete nutrient stores Risks for infant Preterm birth Low birth weight Small for gestational age Prenatal Care Inadequate, delayed, or absent prenatal care may leave maternal nutritional deficiencies untreated Chronic diseases (e.g., hypertension or diabetes) increase risks for infant Prenatal care should start before conception 20% of U.S. women receive no prenatal care in 1st trimester Acquired Immune Deficiency Syndrome HIV and AIDS increase needs for energy and some nutrients Supplementation with some nutrients may have adverse effects Vitamin A Zinc Iron Pregnancy-Induced Hypertension Impairs delivery of oxygen and nutrients to fetus, leading to retarded growth and premature birth May escalate into Preeclampsia: high blood pressure accompanied by protein in urine, headaches, blurred vision, changes in blood clotting, nervous system disorders, and edema Eclampsia (toxemia): convulsions, coma, kidney and liver damage, death of mother and infant Risk factors for preeclampsia and eclampsia High BMI First pregnancy Multiple fetuses Maternal age >35 Existing hypertension Experienced pregnancy-induced hypertension, preeclampsia, or eclampsia during previous pregnancy Family history Some evidence that inadequate nutrient intakes may contribute to development of preeclampsia Calcium (only if intakes were inadequate) Fish oil and sodium restriction appear ineffective in reducing risk Moderate exercise throughout pregnancy may reduce risk Treatment Bed rest Magnesium sulfate: relaxes blood vessels Anti-seizure medication and anti-hypertensive medications are under study Birth Diabetes Mellitus Poor control of type 1 or 2 diabetes mellitus poses risks to infant Major birth defects Spontaneous abortion Infant death Illness Achieving blood glucose control prior to pregnancy and maintaining it throughout pregnancy improves pregnancy outcomes Gestational diabetes develops in ~18% of pregnancies Placental hormones normally decrease insulin sensitivity and mildly increase blood glucose Excessive rise in blood glucose may be detected around weeks 20 - 28 Screening between weeks 24 - 28 is part of routine prenatal care Risk factors for GDM Family history of DM Obesity History of GDM Previously delivered an infant large for gestational age Glycosuria Polycystic ovarian syndrome High-risk groups: Hispanic, Asian, Black or Native American descent Should be screened as soon as possible, with repeated screenings if earlier tests were negative Treatment for GDM Exercise Dietary distribution of low glycemic load carbohydrates throughout day Possibly insulin therapy Consequences of untreated GDM Depletion of fetal iron stores Macrosomia Low fetal blood glucose at birth due to overproduction of insulin Preterm birth Increased risk of birth trauma and malformations Infants may have increased risks of obesity and type 2 DM in adulthood Diabetes usually resolves after birth, but risk of type 2 DM is higher for women who have history of GDM Should have blood glucose screening 6 weeks after giving birth and then annually Maternal Sociocultural Factors Limited income or educational achievement and lack of social support are associated with inadequate maternal diets USDA funds programs to provide food and nutrition education to women with low socioeconomic status Expanded Food and Nutrition Program (EFNEP): educates women about good nutrition, meal planning, and stretching food dollars Supplemental Nutrition Assistance Program (SNAP; also called the Food Stamp program in some states: provides foods for people with limited resources Women, Infants, and Children (WIC) program: provides nutritious foods, nutrition education, and health-care referrals specifically to low-income pregnant, postpartum, and breastfeeding women and their infants and children up to age 5 Maternal Food Supply Environmental Contaminants Routes of contamination Food containers Polluted water Farming practices Food preparation practices Contaminants of particular concern Lead: leaded crystal glasses or some dishes, solder on copper pipes Mercury: fish from polluted waterways Polychlorinated biphenyls: fish from polluted waterways Pesticides: fish from polluted waterways, unwashed fruits and vegetables Recommendations Avoid swordfish, shark, king mackerel, and tilefish Limit intake of other fish and shellfish to 12 oz. (no more than 6 oz. of albacore tuna) per week Thoroughly wash fruits and vegetables Foodborne Pathogens Pathogens of greatest concern Listeria monocytogenes can cause spontaneous abortion, premature delivery, stillbirth, and infections in newborns Toxoplasmosis Foods to avoid Raw sprouts Unpasteurized milk and juices Raw or undercooked meat and eggs Soft cheeses Other recommendations Thoroughly cook leftovers and meats (including processed meats) Avoid litter boxes, kittens, and birds Carefully wash produce to remove soil Thoroughly cook all meat Caffeine Sources Coffee Tea Some soft drinks and energy drinks Chocolate Some medications (e.g., headache and cold remedies) Consequences of intake >500 mg/day Reduced fertility Increased risk of spontaneous absorption Low birth weight infant Increased fetal heart rate Decreased blood flow to placenta Decreased absorption of certain nutrients (e.g., calcium, iron, zinc) Withdrawal symptoms in newborn Recommendations: limit caffeine consumption to 200 mg/day (~2 c coffee or 3 c caffeinated soft drinks) Food Additives Phenylalanine in non-caloric sweeteners can disrupt fetal brain development for mothers with PKU Maternal Lifestyle Women should exercise the most caution while trying to conceive and during the first trimester Alcohol Consequences of alcohol consumption Impaired fertility Displacement of nutrient-dense foods Slowed delivery of nutrients and oxygen to embryo or fetus, thus retarding growth and development Consequences are most severe during first trimester, but damage can occur at any time during pregnancy 6/1000 births are affected by fetal alcohol spectrum disorders (FASD) Facial malformations Growth retardation CNS defects (e.g., mental retardation, small brain size) Learning disabilities Short attention span Hyperactivity Alcohol freely crosses the placenta, intensity is magnified by small fetal size and inability to metabolize alcohol There is no known safe amount of alcohol consumption during pregnancy; total abstinence is recommended Drugs (over-the-counter, prescription, or illegal) Common culprits Aspirin Hormone ointments Nose drops Cold medications Rectal suppositories Weight-control pills Medications prescribed for previous illnesses Marijuana Cocaine Accutane Consequences Depleted nutrient stores Altered nutrient absorption Decreased desire to eat Reduced fetal blood flow Birth defects Herbals and Botanicals May exert potent, drug-like effects All herbal and botanical products should be used with caution under the guidance of a health-care professional Smoking (nicotine and carbon monoxide) Consequences Restricted blood flow Reduced zinc status, which impairs growth Increased risk of spontaneous abortion and placenta problems Premature birth Growth retardation Birth defects Sudden infant death Other factors that compound the effects of smoking Low maternal prepregnancy weight Low weight gain during pregnancy Poor maternal diet Clinical Perspective: Nutrition-Related Physiological Changes of Concern During Pregnancy Heartburn Possible causes Expanding uterus crowds abdominal organs, leading to reflux Hormones of pregnancy relax lower esophageal sphincter Recommendations Eat several small meals Avoid spicy and fatty foods Limit caffeine and chocolate Consume liquids between meals Wait several hours to lie down after eating Elevate head of bed Use of antacids may cause constipation, excessive sodium intake, etc.; consult health-care provider before using them Constipation Possible causes Hormones of pregnancy relax intestinal muscles to slow digestion and increase nutrient absorption, but increased absorption of water can lead to hard, dry stools Growing fetus compresses GI tract May lead to hemorrhoids Recommendations Consume high fiber foods (28 g/day) Drink more fluids (10 c/day) Exercise Adjust dosage of iron supplements Use of stool softeners and laxatives should be guided by health-care professional Nausea and Vomiting Sometimes called morning sickness, but can occur at any time of day Potential causes Increased sense of smell Iron in prenatal supplements Recommendations Breathing cool, fresh air Avoid offensive odors Avoid large fluid intakes early in morning Avoid empty stomach Eat specific foods that ease symptoms (e.g., starchy, bland foods) Postponing use of iron-containing supplements until 2nd trimester Usually eases by 2nd trimester, but 10 - 20% of cases develop into hyperemesis gravidarium May lead to dehydration, malnutrition, and electrolyte imbalances May require medications or hospitalization Edema Potential causes Placental hormones cause fluid retention Expansion of blood volume Enlarging uterus compresses blood vessels in the legs (edema in lower legs is common and expected) If edema is accompanied by high blood pressure, protein in the urine, or if edema fails to subside with elevation of feet, this may be a sign of pregnancy-induced hypertension Lactation General Preparation begins in puberty: hormones stimulate breast development Fat deposition Development of lobules and ducts In early pregnancy, hormones secreted by placenta cause milk-producing glands to mature and lactiferous ducts to become more branched Following childbirth, pituitary hormones initiate milk production (prolactin) and release (oxytocin) Without infant suckling, milk production ceases Milk Production Birth and infant suckling stimulate manufacture and secretion of prolactin from pituitary gland Prolactin stimulates mammary gland to synthesize milk, which promotes milk production Lactation must be initiated shortly after birth or milk supply will cease To establish lactation between mother and infant, sucking should take place every 2 - 3 hours for 15 - 20 minutes on each breast Milk production parallels infant demand Continued suckling stimulates continued lactation, which can be maintained for years Women are able to successfully breastfeed twins or triplets Weaning should be gradual to avoid painful engorgement (e.g., eliminate 1 feeding each week) Release of the Milk from the Breast Let-down reflex is initiated by suckling (and later becomes automatic), which stimulates pituitary gland to release oxytocin Oxytocin causes contraction of breast tissues and release of milk from lobules through ducts to the nipple Let-down reflex can be inhibited by Nervous tension Lack of confidence Fatigue Milk Types and Composition Colostrum: thin, yellowish, immature milk that appears near the end of pregnancy or just after birth Richer in protein, minerals, and vitamin A than mature milk Lower in carbohydrate and calories than mature milk Contains antibodies and immune system cells that pass through the infant’s immature GI tract and impart immune defenses during the first few months of life Lactobacillus bifidus factor encourages growth of L. bifidus and limits growth of potentially toxic bacteria in infant’s GI tract Laxative effect Transitional milk: contains more fat, lactose, water-soluble vitamins, and calories than colostrum Mature milk Thin, watery, bluish tinge Provides 20 kcal/oz. Meets all nutrient needs of growing infant, with exceptions of vitamin D and iron Nutrient Needs of Breastfeeding Women General Nutrient needs and calorie demands of lactation mostly exceed those of pregnancy Iron needs are slightly lower than pregnancy and non-pregnancy RDAs because breast milk contains little iron and menstruation is usually delayed for about 6 months Maternal Nutritional Status Dietary sources and maternal storage of nutrients keep composition and volume of milk at consistent levels Maternal malnutrition must be severe before lactation will cease Excessive intake of macronutrients and fluids usually have no effect on milk composition Proportions of dietary fatty acids may affect milk fat composition Excessive vitamin or mineral intake may increase mineral content of milk Nutrients that are commonly inadequate in diets of lactating women Calcium Magnesium Zinc Folate Vitamin B-6 Adequate fluid intake is vital to prevent dehydration: fluid requirements increase by 32 oz./d (above the 72 oz. recommended for non-pregnant women) Calorie needs for milk production Average breastfeeding woman uses 800 kcal/day during the first 6 months of lactation to produce 750 ml (3 c) milk/day 400 - 500 kcals/day from dietary sources (following same meal plan as for 2nd and 3rd trimesters) allows for gradual loss of stored fat, especially when woman continues breastfeeding for 6 months and does some physical activity Overweight women can rely entirely on stored fat Severe calorie restriction that leads to weight loss > 4 lbs./month can decrease milk production After 6 months of lactation, dietary intake should support calorie needs, especially if woman has lost pregnancy weight BMI <18.5 will likely compromise milk production Food Choices during Lactation Single food items have little effect on quality or amount of milk production Some cultures believe that food items (e.g., garlic) increase milk production, but evidence does not support these beliefs Fortified breakfast cereal or multivitamin and mineral supplement can help meet nutrient needs Sufficient omega-3 fatty acids (fish or supplements) are required for secretion in breast milk to aid in development of infant’s nervous system; follow recommendations for fish intake set for pregnancy Avoidance of peanuts or peanut butter may decrease risk of peanut allergy for infants at high risk for food allergies Experts do not recommend that women restrict their diet as a strategy for preventing food allergies in children Factors Affecting Lactation General Benefits for infant Nutrition Immunity Psychology Benefits for mother Reduced risk of ovarian and premenopausal breast cancers Bone remineralization exceeding pre-lactation levels Weight loss Quicker return of uterus to prepregnancy state Less postpartum bleeding Delayed ovulation, leading to decreased chances of pregnancy in the short term Reduced risk of metabolic syndrome later in life Maternal Weight Obesity may hinder initiation and continuation of breastfeeding May have difficulty getting infant to latch on properly and positioning infant appropriately for breastfeeding Release less prolactin, which can lead to low milk supply More likely to have Cesarean deliveries, which delay the first suckling Supplementing human milk with infant formula may be necessary until milk supply increases Weight loss prior to pregnancy may improve breastfeeding success Maternal Age Infants of adolescent mothers may grow more slowly than infants of older mothers Teen mothers may need assistance to meet their own nutritional needs in addition to those of the infant Maternal Eating Patterns Occasional poor dietary intake is no cause for concern Chronic nutrient and calorie inadequacy may deplete maternal nutrient stores and negatively affect milk supply Maternal and Infant Health Inborn error of metabolism in infant may rule out breastfeeding PKU Galactosemia Infectious diseases may be transmitted through human milk Tuberculosis Hepatitis C Some chronic diseases are incompatible with breastfeeding Cancer treated with chemotherapy HIV Transmission to infants is greatly reduced when HIV-exposed infants or HIV-infected mothers receive antiretroviral (ARV) interventions. If ARVs are available, breastfeeding is recommended In regions of the world where infectious disease and malnutrition are primary causes of death, risk of not breastfeeding outweighs risk of possible transmission of HIV infection Breast surgery may prevent milk production or secretion Sociocultural Factors Breastfeeding is a learned skill; new mothers require: Education Social support (including spouse/partner) Help from knowledgeable health professionals (e.g., lactation consultants) Factors that limit breastfeeding success Lack of information Lack of confidence Lack of role models and/or inadequate support system Sources of accurate breastfeeding knowledge Lactation consultants La Leche League offers classes and information Facts about breastfeeding Practically all women are physically capable of breastfeeding Anatomical problems (e.g., flat or inverted nipples) can be corrected No relationship between breast size and quality or amount of milk produced Women can continue to breastfeed even after returning to work or school Alternate breastfeeding with bottle feeding Manually express or mechanically pump breast milk into sterile container; store in refrigerator or freezer Breastfeeding in public can be done modestly No state has law prohibiting breastfeeding, but indecent exposure may be an offense in some states Infant is receiving adequate milk if the baby has 6+ wet diapers/day and grows normally Although ovulation is delayed by breastfeeding, it is no substitute for reliable birth control Even premature and/or LBW infants can be breastfed, sometimes requiring pumping and fortification with certain nutrients (e.g., calcium, phosphorus, sodium, and protein) Maternal Food Supply Environmental contaminants can appear in milk; effects on infant are unknown Avoid freshwater fish from polluted waters Carefully wash and peel fruits and vegetables Remove fatty portions of meat because contaminants are concentrated in fat tissue Avoid rapid weight loss because toxins that have accumulated in fat tissue may be secreted into breast milk Local health department has information regarding toxic wastes and other contaminants Caffeine may cause irritability, tension, and sleeplessness in infants; avoid caffeine or limit to 1 - 2 c/day Some foods impart unpleasant flavors (e.g., cabbage, chocolate); mothers should pay attention to infants’ behavior Maternal Lifestyle Choices Alcohol, drugs, herbal and botanical products, and nicotine are secreted into breast milk Although amount in breast milk may be small, dose may be potent for small infant Alcohol Reduces milk output Causes infants to drink less and have disrupted sleep patterns Best advice is to avoid alcohol during lactation, but limiting intake and waiting 3 - 4 hours before nursing are generally safe Amount of alcohol in breast milk peaks 30 - 60 minutes after ingestion, then declines Medications should be used with caution Illegal drugs (e.g., marijuana, cocaine) should always be avoided Depress milk production Transmitted to infant via breast milk, slowing development and causing vomiting, tremors, breathing difficulties, and convulsions Drug addicts should not breastfeed their infants Herbal and botanical products should be used with caution; pass into breast milk Smoking and secondhand smoke Lower milk production Lower infant weight gain Nicotine can cause vomiting, slow breathing, increased blood pressure, apathy Benefits of breastfeeding still outweigh risks of nicotine exposure Instructor Manual for Wardlaw's Perspectives in Nutrition Carol Byrd-Bredbenner, Gaile Moe , Jacqueline Berning , Danita Kelley 9780078021411