CH 13 STUDY GUIDES QUESTIONS

Whole grains vs refined grains, vitamin content

Whole grains. These are unrefined grains that haven't had their bran and germ removed by milling. Whole grains are better sources of fiber and other important nutrients, such as selenium, potassium and magnesium. Whole grains are either single foods, such as brown rice and popcorn, or ingredients in products, such as buckwheat in pancakes or whole wheat in bread. Refined grains. Refined grains are milled, a process that strips out both the bran and germ to give them a finer texture and extend their shelf life. The refining process also removes many nutrients, including fiber. Refined grains include white flour, white rice, white bread and degermed cornflower. Many breads, cereals, crackers, desserts and pastries are made with refined grains, too.

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-NIACIN :Symptoms of pellagra include diarrhea and dementia. Thus, pellagra is identified by the 3 Ds: dermatitis, diarrhea, and dementia. Death, the fourth D, can result if the disease is not treated. The niacin deficiency disease pellagra, once a significant public health problem in the U.S., is now eradicated here, thanks to the enrichment of grains and protein-rich diets. Pellagra develops from a poor diet, rather than a bacterial infection. Pellagra has long been associated with corn-based diets. -BIOTIN:Overall, biotin deficiencies are rare. About 1 in 112,000 infants is born with a genetic defect that results in very low amounts of the enzyme biotinidase.27 As a result, these infants cannot break down biocytin in foods for absorption. A biotin deficiency develops, and symptoms (skin rash, hair loss, convulsions, low muscle tone, and impaired growth) occur within a few weeks to months following birth. The affected individual is typically treated throughout life with regular doses of biotin supplements.Term: avidin Def: Protein, found in raw egg whites, that can bind biotin and inhibit its absorption. Cooking destroys avidin.

Conditions/symptoms related to water soluble vitamin deficiencies

-THIAMIN:As described previously, the thiamin deficiency disease beriberi is associated with diets consisting mainly of white rice. For example, in the 1800s, 25 to 40% of those in the Japanese navy experienced beriberi because ship rations included white rice and little else. When meat and legumes were added to the navy rations, beriberi was eliminated Although much less common today, beriberi is still a problem in parts of Asia, particularly among refugees and impoverished elderly people and infants.9 Individuals who abuse alcohol, and those with heart failure, gastrointestinal diseases, or eating disorders, as well as the elderly, also are at risk of thiamin deficiency. -RIBOFLAVIN: deficiency, called ariboflavinosis, primarily affects the mouth, skin, and red blood cells. The symptoms include inflammation of the throat, mouth (stomatitis), and tongue (glossitis); cracking of the tissue around the corners of the mouth (angular cheilitis); and moist, red, scaly skin (seborrheic dermatitis). Anemia, fatigue, confusion, and headaches also may occur. Some of the symptoms of ariboflavinosis may result from deficiencies of other B-vitamins because they work in the same metabolic pathways as riboflavin and are often supplied by the same foods.

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-Vitamin B-12 Deficiency :Researchers in mid-19th-century England noted a form of anemia that causes death within 2 to 5 years of initial diagnosis. They called this disease pernicious anemia Anemia that results from the inability to absorb sufficient vitamin B-12; is associated with nerve degeneration, which can result in eventual paralysis and death. also results from malabsorption caused by various stomach and intestinal problems and the use of some medications. Of course, insufficient vitamin B-12 intake due to very low intake of animal foods also can cause a deficiency VITAMIN C: A deficiency of vitamin C prevents the normal synthesis of collagen, thus causing widespread, significant changes in connective tissue throughout the body. The first signs and symptoms of scurvy, the vitamin C deficiency disease, appear after about 20 to 40 days on a diet free of vitamin C and include fatigue and pinpoint hemorrhages around hair follicles These hemorrhages are the most characteristic sign of scurvy. In addition, the gums and joints bleed, a classic sign of connective tissue failure. Other effects of scurvy include impaired wound healing, bone pain, fractures, and diarrhea. Psychological problems, such as depression, are common in advanced scurvy. Scurvy is fatal if not treated.

Digestion and absorption of Vitamin B-12, factors that interfere with absorption

Factors that Interfere with Absorption Defective/Absence of secretions R-protein, trypsin, intrinsic factor Defective binding of intrinsic factor/B-12 Surgical removal of ileum or stomach Diseases/Conditions Atrophic gastritis (elderly) Infections stomach (H. Pylori), bacterial overgrowth in the intestinal trac

Major functions of water soluble vitamins

Thiamin: Thiamin pyrophosphate (TPP)(Co enzyme form) 1. Decarboxylation reactions 2. Pentose phosphate pathway role Transketolase enzyme Riboflavin: Coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) Energy metabolism Citric Acid Cycle Beta-oxidation Electron transport system Other B vitamin functions Antioxidant function (glutathione synthesis) Niacin: Coenzymes: NAD+ and NADPH Required in at least 200 reactions Macronutrient catabolism Oxidation-reduction reactions Biotin: Coenzyme in carboxylase reactions (adds CO2 ) Macronutrient metabolism Vitamin B-6: Metabolism PLP coenzyme is involved in 100+ reactions (nitrogen compounds) Transamination reactions Glycogenolysis Folate: Central coenzyme form: Tetrahydrofolic acid (THFA) DNA synthesis Amino acid metabolism Homocysteine methionine High homocysteine Issues Neurotransmitter synthesis Vitamin B-12: Vitamin B12 and folate depend on each other for activation Removes methyl group for activation from folate Regeneration of methionine DNA & RNA synthesis Individual roles of vitamin B12 Protects nerve fibers Active in bone cell activity and metabolism Vitamin C: Functions Reduction-oxidation reactions (electron donor) Collagen synthesis Cofactor for metalloenzymes Synthesis of other vital compounds Antioxidant activity Iron absorption Immune function

Food sources of water soluble vitamins

Thiamin: Pork, sunflower seeds and legumes Riboflavin: Milk, enriched grains, eggs, and meat Niacin: Poultry, meat, fish Synthesized in the body (tryptophan niacin) Biotin: Widely distributed in the food supply Whole grains, eggs, nuts and legumes Vitamin B-6:Meat, fish, poultry, fortified cereals, potatoes Folate: Legumes, leafy green vegetables, avocados, and oranges Vitamin B-12: For humans, the sources of vitamin B-12 are foods of animal origin, such as meat, poultry, seafood, eggs, and dairy products. Especially rich sources of vitamin B-12 are organ meats, such as liver, kidneys, and heart, and fortified foods, such as ready-to-eat cereals Vitamin C: Most fruits and vegetables contain some vitamin C, but the richest sources are citrus fruits, peppers, and green vegetables. The major contributors of vitamin C to North American diets are oranges and orange juice, grapefruit and grapefruit juice, tomatoes and tomato juice, fortified fruit drinks, tangerines, and potatoes.

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VITAMIN B-6:MICROCYTIC HYPOCHROMIC ANEMIA: characterized by small, pale red blood cells that lack sufficient hemoglobin and thus have reduced oxygen-carrying ability. It is often caused by an iron deficiency. deficiency is rare in North America. When a deficiency does occur, the symptoms may include seborrheic dermatitis, microcytic hypochromic anemia (from decreased hemoglobin synthesis), convulsions, depression, and confusion due to altered tryptophan metabolism or neurotransmitter synthesis.2,29 About 10% of the U.S. population has low vitamin B-6 blood concentrations.32 The elderly, Blacks, smokers, users of oral contraceptive agents, alcoholics, and those who are underweight or consume poor diets are at risk of low blood vitamin B-6 concentration. FOLATE:A deficiency of folate first affects cell types that are actively synthesizing DNA because these cells have a short life span and rapid turnover rate. For instance, red blood cells have a 120-day life span and are vulnerable to folate deficiency. Without folate, precursor cells in the bone marrow cannot form new DNA and therefore cannot divide normally to become mature red blood cells. The cells grow larger because there is continuous formation of RNA, leading to the increased synthesis of protein and other cell components. Hemoglobin synthesis also intensifies. However, when it is time for the cells to divide, they lack sufficient DNA for normal division.