chapter 15
what is the RDA for iron in women under the age of 50?
18 mg/day #The RDA for adult women is 18 mg/day; it is 8 mg/day for adult men.4 After age 51, the RDA for women drops to 8 mg/day because most women enter menopause and no longer lose iron via menstrual blood. Although iron absorption can vary considerably, the RDA values are Page 547based on the premise that approximately 18% of dietary iron is absorbed each day from typical Westernized diets, such as those eaten in most of North America.4 The Daily Value for iron used on food labels and supplements is 18 mg.
which of the following are good sources of iron?
a)ground beef b)clams c)fortified cereal #Oysters, clams, and other shellfish are good sources of many trace minerals.
How are trace minerals different from major minerals?
a) Requirement for trace minerals are trace are less than 100 mg/day, whereas requirnments for major minerals are 100 mg/day or more.
what is the function of manganese?
a) carbohydrate metabolism #Manganese shares some functional similarities with zinc and copper.21 For example, like zinc and copper, it serves as a cofactor for many enzymes in the body. Manganese-dependent enzymes have important functions in carbohydrate metabolism, gluconeogenesis, collagen formation, and the antioxidant defense network (as Mn superoxide dismutase). In the body, manganese can alternate between different oxidation states (Mn2+ and Mn3+). This enables it to participate in various metabolic reactions
the adult RDA for iodine is___________.
a)150 micrograms
what is the adequate intake for manganese for adult men?
a)2.3mg/day # an Adequate Intake (AI) for manganese was set at 2.3 mg/day for adult men and 1.8 mg/day for adult women.
which of the following are functions of zinc in the human body?
a)DNa synthesis b)taste acuity an wound healing c)cell membrane structure and function #As many as 300 different enzymes in the body require zinc.17 In fact, it is hard to name a body process or structure that isn't affected either directly or indirectly by zinc. Zinc contributes to DNA and RNA synthesis, heme synthesis, bone formation, taste acuity, immune function, reproduction, growth and development, and the antioxidant defense network (as a part of the Cu/Zn superoxide dismutase [SOD] enzyme). In addition, zinc stabilizes the structures of cell membrane proteins, gene transcription fingers (known as "zinc fingers"), and receptor proteins for vitamin A, vitamin D, and thyroid hormone.17
select the primary function of iodine.
a)Thyroid hormone synthesis #Although iodine has a singular function, this function has widespread consequences because of the vital role that thyroid hormones play in maintaining normal metabolism. As a component of T3, iodine is involved in the regulation of many important metabolic and developmental functions. This includes the regulation of basal energy expenditure, macronutrient metabolism, brain and nervous system development, and overall growth.24
consuming what nutrients with meals will increase iron absorption?
a)Vitamin C #Although no iron absorption occurs in the stomach, gastric acid plays an important role in the absorption of nonheme iron by promoting the conversion of ferric (Fe3+) iron to ferrous (Fe2+) iron. If the amount of gastric acid produced is low, less ferric iron is converted to ferrous iron and overall nonheme iron absorption is decreased. This is of concern in individuals who regularly take antacids or other medications to reduce gastric acidity (and symptoms of reflux) as well as in older adults, many of whom have reduced gastric acid production. The factors that affect iron absorption.
the primary function of iron is to_____.
a)aid in transportation #Iron is an essential part of 2 proteins, hemoglobin and myoglobin, that are involved in the transport and metabolism of oxygen. Hemoglobin, which is found in erythrocytes (red blood cells), is composed of 4 iron-containing heme compounds that each bind 1 molecule of oxygen (Fig. 15-3). As a component of hemoglobin, iron carries oxygen in the blood from the lungs to all tissues of the body. It also transports carbon dioxide back to the lungs for expiration. Because the body produces approximately 200 billion erythrocytes each day, much of the body's iron is contained in hemoglobin. If the oxygen-carrying capacity of erythrocytes declines, the kidneys produce the hormone erythropoietin, which stimulates the bone marrow to produce more red blood cells (Fig. 15-4). This, in turn, increases the body's need for iron to support hemoglobin production.
why may fluoride not be an essential nutrient?
a)all basic body functions can occur without it. #Fluoride, the ionic form of fluorine, may not be an essential nutrient because all basic body functions can occur without it. However, in the early 1930s, it was observed that individuals living in the southwestern U.S., where the water naturally contained high concentrations of fluoride, had fewer dental caries (cavities). Many people in these areas also had small spots on their teeth (known as mottling or fluorosis) due to excess fluoride. Although discolored, the mottled teeth were virtually free of dental caries. This discovery led to research studies confirming this mineral's ability to reduce cavities and the start of controlled water fluoridation in parts of the U.S.
which three of the following micronutrients deficiencies may lead to anemia.
a)copper b)vitamin E c)folate
Do goitrogens increase or decrease iodine absorption
a)decrease #The bioavailability of iodine is decreased by compounds, called goitrogens, found in raw vegetables such as turnips, cabbage, Brussels sprouts, cauliflower, broccoli, rutabagas, potatoes, and cassava, as well as peanuts, soy, peaches, and strawberries. Goitrogens decrease iodine absorption and inhibit iodine use by the thyroid gland.
mottled teeth are_________.
a)discolored but resistant to dental caries. # Although discolored, the mottled teeth were virtually free of dental caries. This discovery led to research studies confirming this mineral's ability to reduce cavities and the start of controlled water fluoridation in parts of the U.S.
where are possible functions of chromium?
a)enhances insulin action b)promotes glucose uptake into cells #Chromium may enhance insulin action, promote glucose uptake into cells, and normalize blood sugar levels.
What are the symptoms of iron defieciency anemia?
a)fatigue b)depressed immunity #As iron deficiency progresses and stores are depleted, the lack of iron for heme and hemoglobin synthesis results in the development of iron deficiency anemia. This impairs oxygen transport in the blood, causing fatigue and a decreased ability to perform normal activities. Iron deficiency anemia also compromises immune function, impairs energy metabolism, and delays cognitive development.8,9
selenium acts as an antoxidant as part of a whole group of enzymes?
a)glutathoine peroxidase #Selenium is a component of at least 25 different enzymes and proteins in the body.29 One of its most recognized functions is in the antioxidant defense network, as a part of glutathione peroxidase (GPx) enzymes, thioredoxin reductase enzymes, and selenoprotein P (Fig. 15-18). As part of the antioxidant defense network, selenium helps prevent lipid peroxidation and cell membrane damage.
the enlargement of the thyroid gland that is seen with an iodine deficiency is called _______
a)goiter #(TSH). In response to increased TSH levels, the thyroid gland enlarges in an attempt to increase its efficiency at trapping iodine. The characteristic enlargement of the thyroid gland that occurs is called a goiter.
when the thyroid gland enlargements to be absorb more iodine, this enlargement is termed a ________.
a)goiter #Iodine deficiency disorders, the collective name for endemic goiter and endemic cretinism, occur when dietary iodine intake is insufficient. When iodine availability decreases and plasma levels of T4 hormone drop, the pituitary gland secretes thyroid-stimulating hormone Page 562(TSH). In response to increased TSH levels, the thyroid gland enlarges in an attempt to increase its efficiency at trapping iodine. The characteristic enlargement of the thyroid gland that occurs is called a goiter.
the best food sources of selenium include seafood,meats, cereal, and _______.
a)grains #In general, the best sources of selenium are seafood, meats, cereals, and grains.
whcih of the following food items are best sources of selenium?
a)grains b)meats c)cereals d)seafood #In general, the best sources of selenium are seafood, meats, cereals, and grains (Fig. 15-17).
the functions of fluoride include?
a)helping teeth resist bacterial infections b)helping teeth resist acids c)mineralizing tooth enema! #Although a truly essential function for fluoride has not been described, fluoride is recognized for its beneficial role in supporting the deposition of calcium and phosphorus Page 569in teeth and bones and in protecting against the development of dental caries.36 Fluoride works in several ways to prevent caries. During the development of teeth and bones, fluoride forms hydroxyfluorapatite crystals. These crystals provide greater resistance (than typical hydroxyapatite crystals) to bacteria and acids in the mouth that can erode tooth enamel. Fluoride in the blood contributes to fluoride in the saliva, which promotes the remineralization of enamel lesions and reduces the net loss of minerals from tooth enamel.
what are the symptoms of an iodine toxicity?
a)hypothyroidism B)thyroid cancer #The Upper Level is set at 1100 μg/day for adult men and women to prevent health-related risks.4 Like iodine deficiency, iodine toxicity can cause enlargement of the thyroid gland and decreased thyroid hormone synthesis.28 Toxicities have been reported in Japan, due Page 563to high intakes of iodine rich seaweed, and in Chile, due to high levels of environmental iodine, increased iodine use in water purification, and excessive fortification of salt. Although hypothyroidism is the most common result of iodine toxicity, excess iodine intakes also may increase the risk of hyperthyroidism, autoimmune thyroid disease, and thyroid cancer.
when is the amount of fluoride deposited in teeth and bones greatest?
a)infancy,childhood,adolescence # The absorption of dietary fluoride occurs rapidly in the stomach and small intestine via passive diffusion. Overall, approximately 80 to 90% of fluoride consumed is absorbed. Absorbed fluoride is transported in the bloodstream and concentrated in teeth and the skeleton. The amount of fluoride deposited in the teeth and bones is greatest during infancy, childhood, and adolescence. Calcified tissue deposition and urinary excretion are the major means for removing fluoride from the circulation.
what are the best food sources of iodine
a)iodized salt b)seaweed #The natural iodine content of most foods is relatively low. Saltwater seafood, seaweed, iodized salt, and dairy products are the best sources of iodine (Fig. 15-14). Dairy products are not naturally good sources of iodine, but they often provide significant amounts because iodide is added to cattle feeds and sanitizing solutions used in dairy processing. Breads and cereals also may contribute dietary iodine if they are prepared with iodized salt and/or dough conditioners (compounds that strengthen dough and improve bread volume and texture) because these contain iodates (IO3−).
____________ deficiency is the most widespread trace minerals deficiency in the U.S.
a)iron # As iron deficiency progresses and stores are depleted, the lack of iron for heme and hemoglobin synthesis results in the development of iron deficiency anemia. This impairs oxygen transport in the blood, causing fatigue and a decreased ability to perform normal activities. Iron deficiency anemia also compromises immune function, impairs energy metabolism, and delays cognitive development.8,9
gastric acid plays an important role in the absorption of ________.
a)iron #Although no iron absorption occurs in the stomach, gastric acid plays an important role in the absorption of nonheme iron by promoting the conversion of ferric (Fe3+) iron to ferrous (Fe2+) iron. If the amount of gastric acid produced is low, less ferric iron is converted to ferrous iron and overall nonheme iron absorption is decreased. This is of concern in individuals who regularly take antacids or other medications to reduce gastric acidity (and symptoms of reflux) as well as in older adults, many of whom have reduced gastric acid production. The factors that affect iron absorption.(look at table chapter 15: 15-1).
which mineral deficiency is considered one of the greatest global health risks?
a)iron #Globally, 1 in 4 people has anemia, with a significant portion due to iron deficiency; young children and pregnant women are most commonly affected.3 Although iron deficiency is less prevalent in the U.S. and other industrialized countries, it is considered a leading global health risk by the World Health Organization.3
where will iron be stored in the body?
a)liver #After transferrin binds to its surface receptor, it is engulfed into the cell by endocytosis (see Chapter 4). Within the cell lysosomes, iron is released from transferrin and the receptor-protein complex is returned to the cell surface for reuse. The released iron is utilized for cellular functions or stored in the liver, bone marrow, and spleen with ferritin (the primary storage protein) or hemosiderin.
in which of the following areas are people still risk of developing an iodine deficiency?
a)middle east b)africa #A higher incidence of iodine deficiency disorders occurs in areas of Asia, Africa, the Middle East, and Europe.25,26 The discovery in the early 1920s, by scientists in the U.S. and Switzerland, that iodine can prevent the development of goiter resulted in the fortification of table salt in the U.S. and many other countries. Using a small amount of iodized salt has eradicated endemic iodine deficiency in these areas. Unfortunately, approximately 30% of households worldwide still do not have access to iodized salt.27 Consequently, iodine deficiency remains an international public health concern.27 The World Health Organization (WHO) believes that iodine deficiency is the "greatest single cause of preventable brain damage and mental retardation" and has set a goal of eliminating this deficiency within the next decade by increasing the use of fortified salt, oil, milk, and other food products
who is at risk for developing an iron deficiency?
a)middle-aged men #Many individuals are at risk of iron deficiency and iron deficiency anemia.4 Premature infants (born before 37 weeks of pregnancy) are at increased risk because iron stores needed for the 1st few months of life accumulate during the last weeks of pregnancy. Thus, these infants are born with low stores, which can be depleted quickly by their high iron needs. Young children also are at risk because they are growing fast and typically have low intakes of iron rich meat and high intakes of iron poor cow's milk. One in 4 children in the U.S. ages 12 to 23 months has intakes below the RDA, increasing the risk of iron deficiency.11 In the U.S., iron-fortified formulas and cereals provided by the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) to children from limited-resource families who are at nutritional risk have been instrumental in decreasing rates of iron deficiency anemia. However, in less developed countries, many young children are iron deficient because iron supplementation programs frequently are not available.
overexposure to fluoride can lead to ________ .
a)mottling of teeth
what prevents the body from absorbing too much iron?
a)mucosal block #The amount of mucosal ferritin produced is in proportion to body iron stores. Thus, when iron stores are low, very little ferritin is made,which allows greater amounts of iron to enter the mucosal iron pool for transport out of the enterocytes into the bloodstream. If iron stores are high or saturated, larger amounts of ferritin are made to bind iron as it enters the intestinal cells. Although a portion of this ferritin-bound iron remains in the intestinal iron pool, much of it is excreted when the intestinal cells are sloughed off after several days. This process is called a "mucosal block" because it prevents iron from entering the bloodstream and, in effect, blocks the excess accumulation of iron. Large doses of iron, however, can overtax the mucosal block's protective ability and increase the risk of toxicity.
hemochromatosis overrides what protection the body usually has from iron toxicity?
a)mucous block #Adult iron overload also may result from excess supplementation and frequent blood transfusions. The iron introduced into the body through repeated blood transfusion bypasses the protective mucosal block and can result in dangerously high iron stores in the body if not monitored closely.4
what are the symptoms of a copper toxicity?
a)neurological damage b)nausea and vomiting #The symptoms of toxicity include abdominal pain, nausea, vomiting, and diarrhea. In severe cases, an accumulation of copper in the liver and the brain causes cirrhosis and neurological damage, respectively.
good sources of manganese
a)nuts b)whole grain cereal c)leafy greens #Whole-grain cereals, nuts, legumes, leafy greens, and tea are the best sources of manganese (Fig. 15-13). Meat and dairy products contribute very little manganese to the diet. Based on dietary surveys, the North American diet provides between 2 and 6 mg/day.
Good sources of Molybdenum include
a)nuts b)beans #Molybdenum is often classified as an ultratrace mineral. Although it is needed in extremely small, or "ultratrace," amounts, experts recognize that molybdenum, like many trace minerals, is essential for the activity of several enzymes. Molybdenum content is greatest in plant-based foods, such as grains, legumes, and nuts. Like iodine and selenium, the molybdenum content of foods can vary, depending on the soil in which the plant was grown. The RDA for molybdenum is very small (45 μg/day) and is based on its role as a cofactor required for the activity of several oxidase enzymes.4 The dietary intakes in North America typically meet or exceed the RDA. The Daily Value used on food and supplement labels is 45 μg. Deficiencies of molybdenum are very rare, as are toxicities. However, an Upper Level of 2000 μg/day for adults was set to prevent the development of the goutlike symptoms of joint inflammation noted in several studies.4 Table 15-5 summarizes the function of molybdenum and other trace minerals.
The majority of the worlds population lives in countries where more deaths are attributed to _________.
a)obesity b)overweight #The proportion of overweight children and adults worldwide raises concerns about the potential effects on the development of related disease, such as cardiovascular disease, diabetes, and cancer.38 The majority of the world's population lives in countries where more deaths are attributable to overweight and obesity than to underweight.38
which of the following are good sources of iron?
a)oxalic acid b)phytic acid #Plant-based nonheme iron absorption is hindered by several dietary factors. Phytic acid in whole grains and legumes and oxalic acid in leafy green vegetables bind nonheme iron and reduce its absorption. For this reason, whole grains and leafy green vegetables do not contribute significant amounts Page 549of iron, despite containing relatively high amounts of iron for a plant food.
select the food that is the best food source of selenium
a)oysters #In general, the best sources of selenium are seafood, meats, cereals, and grains.
what is a function of selenium?
a)part of an antioxidant system #Selenium is a component of at least 25 different enzymes and proteins in the body.29 One of its most recognized functions is in the antioxidant defense network, as a part of glutathione peroxidase (GPx) enzymes, thioredoxin reductase enzymes, and selenoprotein P (Fig. 15-18). As part of the antioxidant defense network, selenium helps prevent lipid Page 566peroxidation and cell membrane damage.
who is at the highetsrisk of developing an iron deficiency anemia?
a)premature infants b)teenage girls c)vegans #Many individuals are at risk of iron deficiency and iron deficiency anemia.4 Premature infants (born before 37 weeks of pregnancy) are at increased risk because iron stores needed for the 1st few months of life accumulate during the last weeks of pregnancy. Thus, these infants are born with low stores, which can be depleted quickly by their high iron needs. Young children also are at risk because they are growing fast and typically have low intakes of iron rich meat and high intakes of iron poor cow's milk. One in 4 children in the U.S. ages 12 to 23 months has intakes below the RDA, increasing the risk of iron deficiency.11 In the U.S., iron-fortified formulas and cereals provided by the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) to children from limited-resource families who are at nutritional risk have been instrumental in decreasing rates of iron deficiency anemia. However, in less developed countries, many young children are iron deficient because iron supplementation programs frequently are not available.
select the function o copper in the human body.
a)regulates iron transport b)part of enzymes c)aids in inflamation #Like iron, copper is an important component of many enzymes because of its ability to alternate between 2 oxidation states (Cu1+ and Cu2+). Copper-containing enzymes have many functions in metabolism.21 For example, the enzyme ceruloplasmin (also called ferroxidase I), is involved in oxidizing ferrous (Fe2+) iron to ferric (Fe3+) iron for incorporation into transferrin and subsequent transport from the liver to body cells. One effect of low ceruloplasmin levels is that little iron is transported from storage, resulting in decreased hemoglobin synthesis and the development of anemia. Ceruloplasmin also increases during inflammation and infection to prevent damage to body cells.
which of the following are good food sources of copper?
a)shelfish b)soy milk c)dark chocholate #Copper is found in a variety of foods (Fig. 15-11). Good sources of copper include liver, shellfish, nuts, seeds, lentils, soy products, and dark chocolate. Dried fruits, whole-grain products, and the tap water in many communities also are important sources. Although meat is only a marginal source of copper, it may promote copper absorption from other foods, as it does for iron.
who is at the highest risk of developing an iron deficiency anemia?
a)teenage girls b)premature infants c)vegans #As many as 300 different enzymes in the body require zinc.17 In fact, it is hard to name a body process or structure that isn't affected either directly or indirectly by zinc. Zinc contributes to DNA and RNA synthesis, heme synthesis, bone formation, taste acuity, immune function, reproduction, growth and development, and the antioxidant defense network (as a part of the Cu/Zn superoxide dismutase [SOD] enzyme). In addition, zinc stabilizes the structures of cell membrane proteins, gene transcription fingers (known as "zinc fingers"), and receptor proteins for vitamin A, vitamin D, and thyroid hormone.17
which gland "traps" iodine?
a)thyroid gland
identify a function selenium?
a)thyroid metabolism #Selenium is a component of at least 25 different enzymes and proteins in the body.29 One of its most recognized functions is in the antioxidant defense network, as a part of glutathione peroxidase (GPx) enzymes, thioredoxin reductase enzymes, and selenoprotein P (Fig. 15-18). As part of the antioxidant defense network, selenium helps prevent lipid Page 566peroxidation and cell membrane damage.Its ability to destroy highly reactive peroxyl free radicals spares vitamin E for use in other antioxidant functions. Another important function of selenium is in thyroid metabolism as a part of iodothyronine deiodinase enzymes. Recall from Section 15.5 that the deiodinase enzymes that convert thyroxine (T4) to triiodothyronine (T3) require selenium.
high levels of ingested fluoride can lead to _________ .
a)tooth pitting b)tooth mottling #A lack of fluoride is associated with an increased incidence of dental caries. However, no specific deficiency disorder or disease appears to be caused by insufficient fluoride intake. In contrast, fluoride toxicity has been reported in young children who have swallowed fluoride tablets or solutions. Although rare, acute toxicity can occur rapidly and be life threatening. Thus, fluoridated toothpastes, mouth rinses, and supplements need to be kept out of the reach of children. The signs of toxicity include nausea, vomiting, diarrhea, sweating, spasms, convulsions, and coma.
Chromium is a __________ minerals.
a)trace #The importance of chromium in the diet has been recognized only in recent years. Like many trace minerals, the functions of this nutrient are emerging with advances in research technology.
which of the following vitamins aids in the absorption of nonheme iron?
a)vitamin c #The absorption of nonheme iron can be enhanced by a component of meat called meat protein factor (MPF). Eating even a small amount of meat with nonheme iron-containing foods can be an effective means of boosting nonheme iron absorption. Vitamin C, or other organic acids, in the diet also increases nonheme iron absorption. Vitamin C provides an electron to Fe3+ (ferric iron) to yield Fe2+ (ferrous iron), which then forms a soluble complex with vitamin C. Ferrous iron is better absorbed than ferric iron because it more readily crosses the mucosal layer of the small intestine and reaches the brush border of the intestinal absorptive cells. (Heme iron does not need to undergo this reduction reaction because the iron in heme is already in the more soluble ferrous form.)
what factors increase iron's bioavailability?
a)vitamin c b)heme iron c)meat protein factors
what is the symptom of a zinc deficiency?
poor wound healing
