Chapter 67: Vitamins

Question 1

vitamins

Answer 1

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​

Question 2

intake of vitamins

Answer 2

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​

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Question 3

classification of vitamins

Answer 3

Fat soluble​
Vitamins A, D, E, K​

Water soluble​
Vitamin C​
Vitamin B complex: Thiamin, riboflavin, niacin, pyridoxine, pantothenic acid, biotin, folic acid, cyanocobalamin ​

Question 4

Vitamin A (retinol)

Answer 4

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

Question 5

vitamin D

Answer 5

Regulates calcium and phosphorus​

Deficiency causes rickets or osteomalacia​

Question 6

vitamin E

Answer 6

Antioxidant properties​

Dietary sources: Fresh greens, seeds, oils​

Toxicity may increase the risk for bleeding​

Increased risk of hemorrhagic stroke​

may case some petitache

Question 7

vitamin K

Answer 7

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​

Question 8

vitamin C

Answer 8

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​

Question 9

Vitamin B Complex

Answer 9

Niacin (nicotinic acid)​

Riboflavin (vitamin B2)​

Thiamin (vitamin B1)​

Pyridoxine (vitamin B6)​

Cyanocobalamin (vitamin B12)​

Folic acid​

Question 10

Niacin (Nicotinic Acid) deficiency

Answer 10

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​

Question 11

niacin ADR

Answer 11

Small doses devoid of adverse effects​

Large doses​
Vasodilation with flushing, dizziness, nausea ​

Question 12

niacin therapeutic uses

Answer 12

As a vitamin, used only as treatment for niacin deficiency​

If given in large doses can decrease cholesterol​
Take ASA to help with ADR ​

Question 13

Riboflavin (Vitamin B2)​ actions

Answer 13

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​

Question 14

Riboflavin (Vitamin B2)​ uses

Answer 14

Riboflavin deficiency​
Cracks around corners of mouth, glossitis​

Migraine headaches ​
Take for 3 m​

daily dose: ~400mg

Question 15

Thiamin (Vitamin B1)​

Answer 15

Actions​
Coenzyme for carbohydrate metabolism​
Requirements increased slightly during pregnancy and breastfeeding​

Deficiency​
Beriberi​
Wernicke-Korsakoff syndrome​

Question 16

beriberi

Answer 16

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​

Question 17

Wernicke-Korsakoff syndrome (caused by alcoholism)​

Answer 17

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 ​

Question 18

Pyridoxine (Vitamin B6)​

Answer 18

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​

Question 19

Pyridoxine (Vitamin B6) deficiency

Answer 19

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​

Question 20

Cyanocobalamin (vitamin B12) and folic acid

Answer 20

Both essential factors in the synthesis of DNA​

Deficiency of either manifests as megaloblastic anemia ​

Cyanocobalamin deficiency also results in neurologic damage​

Question 21

Folic Acid

Answer 21

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​

Question 22

Pantothenic Acid

Answer 22

Essential component of two biologically important molecules: Coenzyme A and acyl carrier protein​

​vitamin b5

Question 23

Biotin

Answer 23

Essential cofactor for several reactions involved in the metabolism of carbohydrates and fats​

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