Nutrition Science: NUTR06201 Nathalie Roman-Rivera
Exam #3 Short Answers
80 points total
Question 1: 15 points
Describe in detail the mechanisms involved in intestinal iron absorption. Discuss the independent mechanisms involved in the uptake of both heme and nonheme iron and be sure to include the body’s response to excess iron and insufficient iron intake. Support your answer and site your sources using APA style.
Iron is a trace mineral essential in the human body for cell function; human body needs iron to make hemoglobin and myoglobin (Rolfes, 2018). After Iron sources are ingested this is absorbed in the small intestine and converted into Ferritin which is iron storage protein ; transferrin transport iron concentration through the blood stream to different tissues and cells (Ross, 2012). Iron concentration is stored in the small intestine for 3-5 days and the amount that’s not used is excreted through feces (Rolfes, 2018).
Iron can be ingested in two forms: Heme from animal food sources and Non-heme from plant-derived sources. Non heme iron is only absorbed on the lumen of the intestine and their absorption depends on others vitamins, for example Vitamin C which will enhance the non heme absorption making the individual vulnerable to deficiency. To maintain a proper iron balance depends on iron absorption, transport, storage, recycling, and losses. The hormone hepcidin is produced by the liver and helps to maintain blood iron within the normal range by limiting absorption from the small intestine and controlling release from the liver, spleen, and bone marrow (Rolfes, 2018).
The amount of iron intake depends on the food. When iron intake in excess occurs this leads to deficiency because iron cant be excreted and anemia occurs. This is common among children’s and women’s (Ross,2014). Iron deficiency affects immunity due to his role in increasing free radicals during infections and affects lymphocytes and neutrophil function. In children, iron deficiency is related with respiratory problems and during early childhood can cause irreversible impaired growth and developmental problems. In pregnant women can cause premature delivery and low birth weight. Infants with iron deficiency also showed problems with audition , the mechanism in not understood yet but is related with hypomyelination (Ross, 2014). Elderly population is affected by iron deficiency. Iron toxicity can be caused by genetic or inherited disease. Examples of iron overload by hereditary causes are thalassemia intermedia, Friedreich ataxia, Ferritin mutations in Diabetes Mellitus Type 1, hereditary hemochromatosis. Oxidative stress is one of the causes of iron overload, and this cause a malfunction in the cardiovascular and endocrine system. Excess of iron can also leads to hepatotoxicity (Ross, 2014).
Based on Ross, (2012) food strategies are not effective as adding supplementation on the individual diet at least twice per week to meet the body needs. The RDI for men’s is 7 mg/day and 18mg/day for women in reproductive years (Rolfes, 2018). Food sources includes meat, parsley, clams, tomato juice, broccoli, tofu, potato, tortilla flour, dried fruits, shellfish, fish and legumes.
References:
1) Ross, A. C., Caballero, B., Cousins, R. J., Tucker, K. L., & Ziegler, T. R. (2012). Modern nutrition in health and disease (11th ed.). New York: NY: Lippincott Williams & Wilkins.
2) Rolfes, S. R., Pinna, K., Whitney, E. (2018). Understanding Normal and Clinical Nutrition. (11th ed.). Boston, MA: Cengage Learning.
Question 2: 15 points
Choose one of the three general functional classes of zinc (catalytic, structural, regulatory) and discuss the biochemical and physiologic functions. Provide an example from the functional class you chose. Support your answer and site your sources using APA style.
Zinc is involved in more than 300 enzymes process, covering the 6 types of enzymes. Zinc binding sites are coordinated by four amino acids chains in a tetrahedral form. This forms doesn’t contain regular patterns, providing more flexibility to perform different functions (McCall, 2011). Zinc is a trace-mineral and form part of insulin, immune reactions, transport of vitamin A, taste perception, wound healing and normal fetal development (Rolfes, 2018). Zinc (Zn) finger are structural motifs of proteins, which use cysteine and histidine to form a tetrahedral Zinc (Ross, 2014). In most cases those proteins are interacting with RNA and DNA; for example Transcription factors in which Zn is involved.
For example in transcription factor III (TFIII) the motifs is Xenopiel leavis and Zn interacts within the structure to maintain the external structure ( proper folding) of the protein. Other example is retinoids acid and calcitriol nuclear receptors. About 8% of human genome have zinc finger protein genes (Ross, 2014).
Zn finger proteins acts a modulator and is part of signaling transduction; they bind RNA and help in protein interaction, having transcriptional and translational control; regulates apoptosis, lipid binging and the most important provides protein folding and assembling.
Nitrosative and Oxidative Stress can alter Zinc finger motifs and can cause loss of functions leading to zinc deficiency (Ross,2014).
Large amounts of zinc are associated with insulin secretion of pancreatic beta-cells; Zn metallo. digestive enzyme secreted by pancreatic acinar cells. Zn (ZnT8, ZnT2, ZIP11) stabilize during the acid secretion by parietal cells in the stomach by replacing H+ during gastric acid release. (Ross, 2014).
Zinc ions facilitate diverse essential protein function due to his lack of redox -activity . Zinc finger domains are found in cluster of four or more in a single protein and give stabilization on the structure each protein in order to facilitate DNA and RNA interaction.
Reference:
1) Keith A. McCall, Chih-chin Huang, Carol A. Fierke. (2011). Function and Mechanism of Zinc Metalloenzymes, The Journal of Nutrition, Volume 130, Issue 5.
2) Pace, N.J., Weerapana, E. (2014). Zinc-binging Cysteines: diverse functions and structural motifs. Biomolecules Journal.
3) Ross, A. C., Caballero, B., Cousins, R. J., Tucker, K. L., & Ziegler, T. R. (2012). Modern nutrition in health and disease (11th ed.). New York: NY: Lippincott Williams & Wilkins.
4) Rolfes, S. R., Pinna, K., Whitney, E. (2018). Understanding Normal and Clinical Nutrition. (11th ed.). Boston, MA: Cengage Learning.
Question 3: 12 points
Discuss major risk factors in the development of osteoporosis. What population groups are most at risk? What dietary measures are advocated for high-risk groups?
Bone health depends on calcium (Rolfes, 2018). Calcium is essential for bone mineralization and teeth development. Is involved in muscle contraction and relaxation, nerve function, blood clothing and blood pressure.
Low calcium intake cause abnormal bone mass which leads to Osteoporosis. For elderly population , calcium intake through food is not enough to meet the required amount needed by the body.
Bone strength depends primarily on the born forming years during youth development; children’s that doesn’t get enough calcium wouldn’t have strong bones. More than 90% of Bone Mass is accrued during childhood and adolescence; during aging Osteoclasts activity increases and Osteoblasts activity decreases leading to loss of bone mass.
Osteoporosis is a condition in which bones compromised strength and loss of bone mineral density (BMD) occurs which increase the risk of fracture. Based on Ross, (2014) Osteoporotic bone tissue have deterioration of the micro architecture, with thinner trabeculae. The loss of bone height is the most common deformity caused by a collapse vertebrae.
Risk factors for Osteoporosis include:
o Being a female
o More than 50 yrs.old increase the chances of development
o Hispanic, Caucasian, Asian Nationality
o Family history of Osteoporosis
o History of fractures
o Women with estrogen deficiency and male with testosterone deficiency
o Sedentary lifestyle
o Smoking and alcohol abuse
o Glucocorticoids, aluminum containing anti acids and anti-seizures drugs increase the chances.
To prevent Osteoporosis individuals need to maintain an optimum bone mass and a healthy lifestyle through lifetime. The RDI is 1300 mg/day from 9 years old through 18 years old. Girls are at mayor risk because the low intake during childhood having less bone density . As adults women should take 1,200 mg/day from food sources and 1500 mg/day for postmenopausal women’s (Rolfes, 208).
People in high risk of developing deficiency are the ones that doesn’t consume milk and their diet is lacking of calcium; postmenopausal women’s; elderly people and white women.
Food sources rich in calcium are tofu, small fish with bones, broccoli, chard, book choy, cabbage, kale, rutabaga, legumes and leafy greens (Rolfes, 2018).
Treatments can be combined with calcium supplements and food sources. Individuals need to follow a healthy diet, exercises regularly and low alcohol intake. Bisphosphonates is the most common prescribed drug for Osteoporosis treatment and is proved to be safe and effective for up to 10 years. Dual energy X-ray absorpiometry (DEXA) scan test measure the bone mineral density and is a tool to determine individuals risk of fracture. DEXA provides measurements of bone pelvis and the spine. DEXA is the gold standard to diagnose Osteoporosis.
References:
1) Ross, A. C., Caballero, B., Cousins, R. J., Tucker, K. L., & Ziegler, T. R. (2012). Modern nutrition in health and disease (11th ed.). New York: NY: Lippincott Williams & Wilkins.
2) Rolfes, S. R., Pinna, K., Whitney, E. (2018). Understanding Normal and Clinical Nutrition. (11th ed.). Boston, MA: Cengage Learning.
Question 4: 12 points
Discuss the essential nature of selenium. Where and why are deficiencies observed in the world?
Based on Rolfes, (2018) Selenium have similars characteristics with Sulfur, this similarity allows selenium to substitute sulfur in methionine, cysteine and cystine amino acids.
Selenium is essential for thyroid function and works against oxidation process; is involved in the activation of glutathione peroxidase enzymes which is one of the most powerful antioxidant in the body; activation and conversion process of the enzymes T3 and T4 which are involved in thyroid function; involved in the activation of Thioredoxin reductase which is involved in energy production and metabolism and also works with vitamin E. Some research suggest that Selenium have anticancer properties due to his antioxidants effects; supplements are not recommended in cancer prevention because the high risk of DNA damage in the cell (Ross, 2014).
Selenium enter into the body commonly in two forms: Selenomethionine (plants sources derived) and Selenocysteine (derived from animal sources). Selenomethionine is found in blood and tissues as methionine- containing protein and is used when amino acids are catabolized in the liver or in the kidney. The selenium enters in the metabolic pool and is added as selenoproteins and transported to others organs or excreted through respiration. (Ross, 2014)
Selenium is found in soil, seafood and organ meats; individuals that growth in areas that soil is lack of selenium are in high risk of deficiency (Rolfes, 2018). In China selenium deficiency is observed and is associated with Keshan Disease, a cardiomyopathy condition caused by a virus or a toxin where adequate amounts of selenium intake prevent the development of it, this condition is seen in children and adolescents (Ross, 2014). Symptoms of selenium deficiency includes impaired cognition and weak immune system (Rolfes, 2018). Based on Ross, (2014) China and British populations are in high risk to develop deficiency due to the lack of selenium amounts int heir soils. The combination of Vitamin E deficiency with Selenium deficiency causes liver necrosis , exudative diathesis and white muscle disease (Ross, 2014).
Selenium status can be evaluated through dietary intake or biochemical tests. The Recommended Intake for infants is in between 15-20 ug/day; children between 1-3 yrs.old is 20 ug/day, 4-8 yrs. Old is 30 ug/day and 9-13 yrs. Old is 40 ug/day; adolescents born 14-18 yrs old is 55 ug/day and adults 19-55 or more is 55 ug/day; Pregnant women should intake 60 ug/day and lactating women should consume 70 ug/day (Ross, 2014).
Other food sources rich in selenium includes brazil nuts, oysters, seafood, meat and grains.
References:
1) Ross, A. C., Caballero, B., Cousins, R. J., Tucker, K. L., & Ziegler, T. R. (2012). Modern nutrition in health and disease (11th ed.). New York: NY: Lippincott Williams & Wilkins.
2) Rolfes, S. R., Pinna, K., Whitney, E. (2018). Understanding Normal and Clinical Nutrition. (11th ed.). Boston, MA: Cengage Learning.
Question 5: 10 points
Explain how a deficiency of copper can lead to "iron deficiency" anemia.
Copper is essential for different enzymes activities that have metabolic roles in which all of them involves oxygen and oxygen radicals reactions. Some enzymes that contains copper catalyze the oxidation of ferrous iron to ferric iron , which allows iron binds to transferrin being this a key role for hemoglobin synthesis (Rolfes, 2018) , this is why copper deficiency can lead to iron deficiency anemia. Aging influence Copper and iron interactions in all organs that manage the levels of metal in the human body (Collins, 2010).
Copper deficiency cause alteration in immune and cardiovascular functions and skeletal abnormalities. Copper deficiency is accompanied with low serum ferroxidase activity; which is the main cause of anemia, leukopenia and neutropenia (Ross, 2014).
Dietary intakes of Copper for adults includes 900 ug/day for 19-51+ yrs.old , pregnant women between 14-50 yrs.old should take 1,000 ug/day and lactating women 1,300 ug/day Ross, 2014). Sources of Copper are whole grains, shellfish, seeds and legumes. Toxicity is rare but can lead into liver damage (Rolfes, 2018).
Reference:
1) Ross, A. C., Caballero, B., Cousins, R. J., Tucker, K. L., & Ziegler, T. R. (2012). Modern nutrition in health and disease (11th ed.). New York: NY: Lippincott Williams & Wilkins.
2) Rolfes, S. R., Pinna, K., Whitney, E. (2018). Understanding Normal and Clinical Nutrition. (11th ed.). Boston, MA: Cengage Learning.
3) Collins, J. F., Prohaska, J. R., & Knutson, M. D. (2010). Metabolic crossroads of iron and copper. Nutrition reviews.
Question 6: 16 points
In your opinion, what is the ideal macronutrient distribution for improving body composition (could be losing fat, gaining muscle; weight gain for those underweight, etc.)? Why? Please support your answer with additional resources. Be sure to cite your sources.
Macronutrients are chemical compounds that individuals consume in daily basis. Macronutrients are displayed in grams on nutritional labels as carbohydrates, proteins and fats and they are essential and required by large amounts in the body (Rolfes,2018). They are essential for an optimum body composition and should be combined with an healthy and active lifestyle. Macronutrients are essential for the body energy metabolism, and are important factors to build body tissue and acts as regulators in various body activities (Rolfes, 2018). Individual body composition reflects their accumulation of nutrients and substrates that they have acquired and retaining in their body (Ross, 2014).
The start point to improve body mass composition in Obese individuals will be losing fat; whit 45% of calories coming from protein, 30% from carbohydrates and 25% from fat. Protein is the most satiating macronutrient and high protein diets can be helpful for calorie intake restriction (Tang, 2018). According to Current Sport Medicine (2005) individuals should consume two essential fatty-acids: linoleic acid and linolenic, men should take 14-17 g/day for the first and 1.6 g/day for the later. Women needs 11-12 g/day for the first and then 1.1 g/day. Water or fluid intake between 3.0L and 2.2L per day. Macronutrient intake will depends on the individual goals and body mass index, this intake should be determined by a nutritionist. Proteins storages is limited, protein is found in muscle and skin and helps to regulates digestion and energy metabolism (Rolfes, 2018).
Reference:
1) Monroe, M.M., (2005). Exercise and the Institute of Medicine recommendations for nutrition. The Journal of Current Sports Medicine Reports.
2) Wang,T. (2018). How to calculate Macros to lose fat and maintain muscle.
3) Rolfes, S. R., Pinna, K., Whitney, E. (2018). Understanding Normal and Clinical Nutrition. (11th ed.). Boston, MA: Cengage Learning.