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 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.