Chapter 67: Vitamins Flashcards
vitamins
Organic compounds
Required in minute amounts for growth and maintenance of health
Are not a source of energy
Essential for energy transformation and regulation of metabolic processes
Several vitamins are inactive in native form and must be converted to active compounds in the body
intake of vitamins
Recommended dietary allowances (RDAs) for vitamins are set by the Food and Nutrition Board of the National Academy of Sciences
RDAs represent the average daily dietary intake sufficient to meet the nutrient requirements of nearly all healthy individuals (97% to 98%) in a particular life stage or gender group
The tolerable upper intake limit (UL) for a vitamin is the highest average daily intake that can be consumed by nearly everyone without significant risk of adverse effects
The UL is an index of safety; it is not a recommendation to exceed the RDA
The estimated average requirement (EAR) is the level of intake that meets nutritional requirements for 50% of the healthy individuals in any life stage or gender group
The acceptable macronutrient distribution range (AMDR) is a range of macronutrients (e.g., proteins, carbohydrates, fats) associated with optimal health. Intake of a nutrient below the established range for that nutrient increases the risk of malnourishment. Intake of a nutrient above the established range for that nutrient increases the risk of chronic diseases
classification of vitamins
Fat soluble
Vitamins A, D, E, K
Water soluble
Vitamin C
Vitamin B complex: Thiamin, riboflavin, niacin, pyridoxine, pantothenic acid, biotin, folic acid, cyanocobalamin
Vitamin A (retinol)
Multiple functions in the eyes
Toxicity
Teratogenic, birth defects, hypervitaminosis liver injury, bone-related disorders
Deficiency results in:
Night blindness
Xerophthalmia
Keratomalacia
Blindness
Therapeutic uses
For eyes
should have 3,000mg/day
vitamin D
Regulates calcium and phosphorus
Deficiency causes rickets or osteomalacia
vitamin E
Antioxidant properties
Dietary sources: Fresh greens, seeds, oils
Toxicity may increase the risk for bleeding
Increased risk of hemorrhagic stroke
may case some petitache
vitamin K
Action required for synthesis of prothrombin and other clotting factors
Deficiency produces bleeding
Adverse effects
Hypersensitivity reaction
Hyperbilirubinemia in parenteral administration to newborns
Therapeutic use
Correction or prevention of hypoprothrombinemia and bleeding caused by vitamin K deficiency
Control of hemorrhage caused by warfarin
vitamin C
Action required for production of collagen and other compounds that bind cells together
Part of the biochemical reaction for the synthesis of adrenal steroids
Sources
Citrus fruits/juices, tomatoes, potatoes, strawberries, melons, spinach, broccoli
Has antioxidant properties
Facilitates iron absorption
Deficiency can lead to scurvy
Vitamin B Complex
Niacin (nicotinic acid)
Riboflavin (vitamin B2)
Thiamin (vitamin B1)
Pyridoxine (vitamin B6)
Cyanocobalamin (vitamin B12)
Folic acid
Niacin (Nicotinic Acid) deficiency
Deficiency
Pellagra: Dermatitis characterized by scaling and cracking of the skin in areas exposed to the sun
GI disturbances
Central nervous system (CNS)
Irritability, insomnia, memory loss, anxiety, dementia
niacin ADR
Small doses devoid of adverse effects
Large doses
Vasodilation with flushing, dizziness, nausea
niacin therapeutic uses
As a vitamin, used only as treatment for niacin deficiency
If given in large doses can decrease cholesterol
Take ASA to help with ADR
Riboflavin (Vitamin B2) actions
Involved in numerous enzymatic reactions
First, must be changed to flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN)
Adverse effects
None for humans, no UL
Riboflavin (Vitamin B2) uses
Riboflavin deficiency
Cracks around corners of mouth, glossitis
Migraine headaches
Take for 3 m
daily dose: ~400mg
Thiamin (Vitamin B1)
Actions
Coenzyme for carbohydrate metabolism
Requirements increased slightly during pregnancy and breastfeeding
Deficiency
Beriberi
Wernicke-Korsakoff syndrome
beriberi
Wet beriberi
Fluid accumulation in the legs
Cardiovascular complications (palpitations, electrocardiograph [ECG] abnormalities, high-output heart failure)
May progress to circulatory collapse and death
Recovery is dramatic with replacement therapy
Dry beriberi
Neurologic and motor deficits, no edema or cardiovascular symptoms
Recovery is slow
Wernicke-Korsakoff syndrome (caused by alcoholism)
Alcoholism is the most common cause of thiamin deficiency in the United States
Serious CNS disorder (neurologic and psychologic)
Nystagmus, diplopia, ataxia, inability to remember recent past
Pyridoxine (Vitamin B6)
Coenzyme in the metabolism of amino acids and proteins
Must first be converted to its active form, pyridoxal phosphate
Sources
Fortified breakfast cereals, meat, fish, poultry, white potatoes, other starchy vegetables, noncitrus fruits
Pyridoxine (Vitamin B6) deficiency
Deficiency
May result from poor diet, isoniazid use, inborn errors of metabolism
Symptoms
Seborrheic dermatitis, microcytic anemia, peripheral neuritis, convulsions, depression, confusion
Dietary deficiency of vitamin B6 is rare in the United States except among alcoholics
Cyanocobalamin (vitamin B12) and folic acid
Both essential factors in the synthesis of DNA
Deficiency of either manifests as megaloblastic anemia
Cyanocobalamin deficiency also results in neurologic damage
Folic Acid
Food folate versus synthetic folate
Synthetic form is more stable
U.S. Food and Drug Administration (FDA) ordered synthetic folate to be added to all enriched grain products
Deficiency of folic acid during pregnancy can impair CNS development
Can result in neural tube defects, anencephaly, spina bifida
Important for any patient who may become pregnant to take additional folic acid
Pantothenic Acid
Essential component of two biologically important molecules: Coenzyme A and acyl carrier protein
vitamin b5
Biotin
Essential cofactor for several reactions involved in the metabolism of carbohydrates and fats
