1. Chapter 8: Nutrients Involved in Energy Metabolism
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2. 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
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4. 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
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7. 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
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10. 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
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13. 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
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15. 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
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16. 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)
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20. 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.
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22. 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
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24. 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
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27. 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
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29. 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
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30. 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
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33. 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
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34. 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
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35. 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
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36. 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
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38. Minerals: Sulfur 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
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39. 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
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