Nutrients Involved in Energy Metabolism 8 Nutrients Involved in Energy Metabolism 1

Energy Metabolism Vitamins and minerals Do not directly provide energy Are needed for generating energy from macronutrients B-complex vitamins are particularly important in assisting energy metabolism Often function as coenzymes 2

Energy Metabolism 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 in cell regeneration and red blood cell synthesis 4

Thiamin (vitamin B1) Coenzyme thiamin pyrophosphate is required for metabolism of carbohydrate and branched- chain amino acids Assists in production of DNA and RNA and synthesis of neurotransmitters Good sources: pork products, sunflower seeds, beans, whole or enriched grains Deficiency (beriberi): muscle wasting, nerve damage 8

Riboflavin (Vitamin B2) Involved in oxidation−reduction reactions Part of coenzyme glutathione peroxidase (antioxidant) Good sources: milk, enriched foods, meat Light sensitive (use opaque milk cartons) Ariboflavinosis: riboflavin deficiency; sore throat, swollen mucous membranes 11

Niacin (Vitamin B3) Two forms: nicotinic acid and nicotinamide Required for oxidation–reduction reactions of carbohydrates, proteins, and fats Can be made from amino acid tryptophan Good sources: meat, fish, poultry, enriched breads and cereals Toxicity symptoms from supplements Pellagra: severe niacin deficiency 15

Vitamin B6 (Pyridoxine) Group of three related compounds Coenzyme in amino acid metabolism and gluconeogenesis Good sources: meat, fish, poultry, enriched cereals, starchy vegetables Toxicity from high-dose supplements: nerve damage, skin lesions Deficiency involves skin, blood, nerve tissues 17

Pantothenic Acid Essential for fatty acid metabolism Required for synthesizing cholesterol, steroids, detoxification of drugs Good sources: chicken, beef, egg yolk, potatoes, oat cereals, tomato products No adverse effects from excess amounts Deficiencies are very rare 21

Biotin Coenzymes for fatty acid synthesis, gluconeogenesis Carbohydrate, fat, and protein metabolism Content determined for very few foods Deficiency seen in large consumption of raw egg whites over time 23

Choline Vitamin-like substance: metabolism, cell membranes, neurotransmission Fat and cholesterol metabolism/transport Homocysteine metabolism Widespread in foods Deficiency: fat accumulation in the liver Toxicity from excess supplementation 25

Iodine Component of thyroid hormones Regulates body temperature, metabolism Important for reproduction and growth Good sources: saltwater fish, iodized salt, foods prepared with iodized salt Excess interferes with thyroid function Goiter: enlarged thyroid gland 26

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 29

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 30

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 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 31

Manganese Cofactor in protein, fat, and carbohydrate metabolism, gluconeogenesis, cholesterol synthesis, and urea formation Part of antioxidant superoxide dismutase Good sources: whole-grain foods Toxicity impairs the nervous system, causing spasms and tremors 32

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 34

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 35