Chapter 8: Nutrients Involved in Energy Metabolism

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Chapter 8 Lecture
Chapter 8:
Nutrients
Involved in
Energy
Metabolism
© 2017 Pearson Education, Inc.
Energy Metabolism
• Vitamins and minerals
• 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.)
• Coenzyme: a molecule that combines with an
enzyme to activate it
• Thiamin, riboflavin, vitamin B6, niacin,
pantothenic acid, and biotin function primarily
in energy metabolism
• 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)
• Coenzyme thiamin diphosphate is required for
metabolism of glucose and branched-chain
amino acids
• 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)
• Involved in oxidation−reduction reactions within
the electron transport chain
• Part of coenzyme required by glutathione
peroxidase to fight oxidative damage
(antioxidant)
• 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)
• 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)
• Group of three related compounds
• Roles include:
• Amino acid and carbohydrate metabolism
• Gluconeogenesis
• Neurotransmitter and heme synthesis
• Immune function
• Metabolism of niacin, folate and carnitine
• Reduction in cardiovascular disease
© 2017 Pearson Education, Inc.
Vitamins: Vitamin B6 (Pyridoxine) (cont.)
• 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
• Works with enzymes
• These enzymes are critical for DNA synthesis,
cell differentiation, amino acid metabolism
• 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)
• Includes a number of compounds that have a
cobalt center surrounded by a ring structure
• 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
• 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
• No adverse effects from excess amounts
• Deficiencies are rare
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Biotin
• A component of coenzymes used for fatty acid
synthesis, gluconeogenesis
• Also contributes to carbohydrate, fat, and protein
metabolism
• Content had been determined for very few foods
• Deficiencies are seen in large consumption of
raw egg whites over time, and in people who
must consume food intravenously
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Vitamins: Choline
• Vitamin-like substance: metabolism, cell
membranes, neurotransmission (acetylcholine)
• Fat and cholesterol metabolism/transport
• Homocysteine metabolism
• Widespread in foods
• Deficiency: fat accumulation in the liver
• Toxicity from excess supplementation
© 2017 Pearson Education, Inc.
Minerals: Iodine
•
•
•
•
Component of thyroid hormones
Regulates body temperature, metabolism
Important for reproduction and growth
Food sources: saltwater fish, iodized salt, foods
prepared with iodized salt
• Excess interferes with thyroid function
• Goiter (enlarged thyroid gland) occurs with both
toxicity and deficiency
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Minerals: Iodine
• Iodine deficiency disorders (IDDs)
• Cretinism: mental retardation, stunted
growth
• Hypothyroidism: low thyroid hormone
results in decreased body temperature, cold
intolerance, weight gain, fatigue,
sluggishness
© 2017 Pearson Education, Inc.
Minerals: Iodine
• Hyperthyroidism: high levels of thyroid
hormone caused by Graves' disease
• Weight loss, increased heat production,
muscular tremors, nervousness, racing
heartbeat, and protrusion of the eyes
© 2017 Pearson Education, Inc.
Minerals: Chromium
• Assists insulin to transport glucose from the
bloodstream into the cells
• Important for RNA and DNA metabolism
• Supports immune function and growth
• Dietary adequacy is controversial
• Widely distributed in foods
• High-dose supplementation safety is unknown
• Deficiency induced in labs: inhibit glucose
uptake into the cells, causing a rise in blood
glucose and insulin levels
© 2017 Pearson Education, Inc.
Minerals: Manganese
• A cofactor in protein, fat, and carbohydrate
metabolism, gluconeogenesis, cholesterol
synthesis, and urea formation
• Part of antioxidant enzyme superoxide
dismutase
• Food sources: whole-grain foods
• Toxicity impairs the nervous system, causing
spasms and tremors
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Minerals: Sulfur
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A major mineral
Component of thiamin and biotin
Part of amino acids: methionine, cysteine
Required by liver for alcohol detoxification
Assists in maintaining acid–base balance
Obtained from dietary proteins
No known toxicity or deficiency symptoms
© 2017 Pearson Education, Inc.
Inadequate B-Vitamin Intake
• Impacts ability to perform physical activity
• Limited studies show poor work performance:
lower intensity and duration
• Diets high in unenriched processed foods
provide inadequate levels of B-vitamins
• Some B-vitamins lost in milling of grains are
replaced by the enrichment process
© 2017 Pearson Education, Inc.
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