Defined
Vitamins
Vitamin Organic compounds Not energy yielding Essential nutrients
Cannot be synthesized in sufficient quantity to meet the body's needs Must be supplied by the diet
Vitamin Defined
Not digested or broken down in GI tract Required in only minute amounts Essential for growth and maintenance Participants in chemical reactions including those of metabolism
Often functioning as co-enzymes
Classification
Fat Soluble A, D, E and K
Water soluble All others
History
1747 Lind Scurvy 1897 Eijkman Beriberi 1912 McCollum Vitamin A (1916) 1912 Funk "Vital Amines" 1940's Water soluble B and C vitamins
Vitamin Facts
Severe lack can lead to development of deficiency diseases Diets seldom deficient in only one vitamin Need for most vitamins increase during
pregnancy lactation periods of rapid growth
Vitamin Facts
Water soluble vitamins are not stored in the body to any great extent Must be consumed regularly Excess amounts usually not dangerous but wasteful Fat soluble vitamins can be stored in body Excess amounts can become toxic Mostly from supplements
Vitamin Facts
Vitamin content of food can be reduced by:
Exposure to oxygen Exposure to light Cooking in alkaline solution Processing
Discarding
cooking/soaking water
Vitamin Facts
A diet based on a wide variety of whole foods will provide an adequate intake of vitamins and minerals
Vitamins of Metabolism
Vitamins and Metabolism
Vitamins and minerals
Are required for proper metabolism Do not directly provide energy Are necessary for obtaining energy from the macronutrients Often function as coenzymes
Vitamins and Metabolism
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Co-Enzyme
FAD
B6
Niacin B6 Pantothenic Acid Riboflavin Niacin
Thiamin
Niacin Niacin
Pantothenic Acid
B6 B6 B6
Figure 8.3
Riboflavin
Niacin Thiamin Riboflavin
Water Soluble Vitamins Water Soluble Vitamins
Characteristics
Hydrophilic Absorbed in the bloodstream Circulates freely in the blood Needed in frequent small doses Excess vitamins are excreted in the urine Generally not toxic
Examples
Vitamin C B vitamins
B-complex Vitamins
The B-complex vitamins are especially important for energy metabolism.
thiamin (B1) riboflavin (B2) niacin vitamin B6 folate * vitamin B12 * pantothenic acid biotin
*Will cover in later chapter
Thiamin B1
Function
Coenzyme
Energy metabolism (CHO and some amino acids) DNA and RNA synthesis
Nervous system function
Stability
Damaged by heat Lost in water
Deficiency
reduced absorption increased excretion
B-complex Vitamins
Thiamin (vitamin B1)
Good food sources:
pork products whole grains enriched foods
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Thiamin Deficiency
Beriberi
Alcohol Thiamin Deficiency
Wernicke Korsakoff Syndrome
Disorientation Loss of short-term memory Jerky eye movements Staggering gait
Riboflavin B2
Function
Coenzyme Energy metabolism (FAD and FMN) Healthy skin Normal vision
Stability
Destroyed by ultraviolet light and irradiation Stable in heat
RDA
1.3 mg/day males 1.1 mg/day females
Toxicity None
B-complex Vitamins
Riboflavin (vitamin B2)
Good food sources milk enriched foods meat
Riboflavin Deficiency
Cheilosis cracks around the mouth
Deficiency is rare Eye problems Skin disorders Cheilosis Inflamed tongue Hypersensitivity to light
Niacin B3
Nicotinic acid and nicotinamide
Function
Coenzyme - NAD
Energy metabolism (CHO, fat, protein) Alcohol Metabolism
RDA
16 mg niacin NE males (niacin equivalent) 14 mg NE females
convert Can the AA tryptophan --> niacin 60 mg tryptophan = 1 mg niacin
Niacin
Good food sources:
meat fish poultry enriched bread products
Niacin Deficiency
Pellagra "rough skin" Diarrhea Dermatitis Dementia Low protein and Low tryptophan corn
Niacin Toxicity
Not caused by food intake Pharmacological doses used to treat high cholesterol - Painful flush (niacin flush) - Excessive sweating - Liver damage - GI disturbance Tolerable Upper Limit - 35 mg/day - Based on flushing
Biotin
Function Coenzyme Energy metabolism (CHO, fat, protein) gluconeogenesis Adequate intake rather than RDA Deficiency Rare Raw egg white Avidin binds Biotin Toxicity -- none
Biotin Sources
Found in a wide assortment of foods including:
Pantothenic Acid
Function
Coenzyme
Energy metabolism component of Co-A
Adequate Intake rather than RDA Deficiency
Very rare
Toxicity
None
Pantothenic Acid
Good sources: chicken, beef, egg yolk, potatoes, oat cereals, tomato products
B6
Pyridoxal, Pyridoxine & Pyridoxamine
Function
Coenzyme Amino Acid metabolism (very involved all aspects) Glycogen breakdown Heme synthesis Neurotransmitter synthesis
RDA Deficiency Rare Toxicity with supplements
Nerve damage UL 100 mg/day
B6
Good sources:
enriched cereals meat fish poultry starchy vegetables
Copyright 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Choline
Choline is a vitamin-like substance.
Assists in homocysteine metabolism Accelerates the synthesis of acetylcholine, a neurotransmitter Good sources: milk, liver, eggs, peanuts Deficiency can lead to fat accumulation in the liver Toxicity can result from supplements
B-vitamin Status
Poor B-vitamin status impacts exercise
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
Minerals of Metabolism
Iodine
Iodine is a trace mineral.
Critical for the synthesis of thyroid hormones Thyroid hormones regulate body temperature and resting metabolic rate Important for healthy reproduction and growth Good sources: saltwater fish, shrimp, iodized salt, milk and dairy products
Iodine
Excess iodine
Interferes with thyroid function
Iodine deficiency disorders (IDDs)
Goiter thyroid enlarges to more iodine capture
Iodine
Iodine deficiency disorders
Cretinism mental retardation from iodine deficiency during embryonic development Hypothyroidism low thyroid hormone results in low body temperature, cold intolerance, weight loss, fatigue
Chromium
Chromium is a trace mineral Assists insulin to transport glucose from the bloodstream into the cells Important for RNA and DNA metabolism Supports normal growth and immune function Good sources: mushrooms, prunes, dark chocolate, nuts, whole grains Chromium deficiency uncommon Induced in labs: raises blood glucose and insulin High-dose supplementation safety is unknown Chromium and weight loss???
Manganese
Manganese is a trace mineral.
Coenzyme involved in energy metabolism Part of the antioxidant enzyme superoxide dismutase Good sources: whole-grain foods, brown rice, pineapple, pine nuts, okra, spinach Toxicity impairs the nervous system causing spasms and tremors
Sulfur
Sulfur is a major mineral.
Component of thiamin and biotin Required for detoxification of alcohol and drugs by the liver Found in a few amino acids - structure Sufficient sulfur can be supplied from the protein in our diets
Table 8.1
Table 8.1
Table 8.1
Table 8.1
Table 8.2