The science of nutrition 4th edition thompson manore vaughan chapter 08
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Chapter 8 Lecture
Chapter 8:
Nutrients Involved in Energy
Metabolism
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Energy Metabolism
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Vitamins and minerals
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Do not directly provide energy
Are needed for generating energy from macronutrients
Often function as coenzymes
B-vitamins are particularly important in assisting energy metabolism
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Energy Metabolism (cont.)
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Coenzyme: a molecule that combines with an enzyme to activate it
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Thiamin, riboflavin, vitamin B6, niacin, pantothenic acid, and biotin function
primarily in energy metabolism
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Folate and vitamin B12 function secondarily in cell regeneration and red blood
cell synthesis
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Thiamin (Vitamin B1)
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Coenzyme thiamin diphosphate is required for metabolism of glucose and
branched-chain amino acids
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Assists in production of DNA and RNA and synthesis of neurotransmitters
Food sources: pork products, sunflower seeds, beans, whole or enriched grains
Deficiency (beriberi): muscle wasting, nerve damage
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Riboflavin (Vitamin B2)
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Involved in oxidation−reduction reactions within the electron transport chain
Part of coenzyme required by glutathione peroxidase to fight oxidative damage
(antioxidant)
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Food sources: milk, dairy, eggs, meat, broccoli, enriched grains and breads
Light sensitive (use opaque milk cartons)
Ariboflavinosis: riboflavin deficiency; sore throat, swollen mucous membranes
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Niacin (Vitamin B3)
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Two forms: nicotinic acid and nicotinamide
Required for oxidation–reduction reactions of carbohydrates, proteins, and fats
Can be made in limited amounts from amino acid tryptophan
Food sources: meat, fish, poultry, enriched breads and cereals
Toxicity symptoms from supplements
Pellagra: severe niacin deficiency
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Vitamin B6 (Pyridoxine)
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Group of three related compounds
Roles include:
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Amino acid and carbohydrate metabolism
Gluconeogenesis
Neurotransmitter and heme synthesis
Immune function
Metabolism of niacin, folate and carnitine
Reduction in cardiovascular disease
Vitamins: Vitamin B6 (Pyridoxine) (cont.)
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Food sources: meat, fish (tuna), poultry, enriched cereals, starchy vegetables
Toxicity from high-dose supplements: nerve damage, skin lesions
Deficiency affects skin, blood, nerve tissues (anemia, convulsions, depression, and
confusion)
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Folate
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Works with enzymes
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These enzymes are critical for DNA synthesis, cell differentiation, amino acid
metabolism
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Synthesis of new cells and repair of damaged cells
Plays a special role in embryo development
Deficiency issues include neural tube defects in infants, anemia, and heart disease
Food sources include green leafy vegetables, bread and grain products (fortified), liver,
lentils, asparagus, and oatmeal.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Vitamin B12 (Cyanocobalamin)
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Includes a number of compounds that have a cobalt center surrounded by a ring
structure
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Works with coenzymes to assist DNA synthesis for the formation of red blood cells
Essential for nervous system functioning
Food sources are animal and non-plant products; meat, eggs, dairy, and seafood
Absorption is complex and requires intrinsic factor
Deficiencies are rare; associated with anemia
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Pantothenic Acid
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Essential for fatty acid metabolism
Required for synthesizing cholesterol, steroids, detoxification of drugs
Food sources: chicken, beef, egg yolk, potatoes, oat cereals, tomato products,
certain mushrooms
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No adverse effects from excess amounts
Deficiencies are rare
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
