Vitamins

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Chapter 7

• Vitamins

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Key Concepts

• Noncaloric
• Essential nutrients necessary for many metabolic
  tasks and the prevention of certain diseases
• Organic substances
• Needed by body for normal metabolism, growth
  maintenance

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Key Concepts

• Vitamins do not provide energy
• Vitamins work as coenzymes to activate other
  enzymes in the body

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Discovery Early Observations

• Discovered while searching for cures for classic
  diseases
• Dr. James Lind, 1753
• Sailors dying on long voyages without fresh food
• Scurvy deficiency vitamin C, causes severe
  bleeding
• Lemons and limes provided, no one became ill

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Era of Vitamin Discovery

• Most vitamins discovered in early 1900s
• At first scientists assigned letters to each
  vitamin
• A, C, D, E, K
• This practice was abandoned in favor of more
  specific names
• Riboflavin, niacin, thiamine, etc.

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Definition of Vitamin

• vital, organic substance
• only necessary in extremely small amounts.
• cannot be manufactured by the body in sufficient
  quantities to sustain life
• Vitamins micronutrients
• Carb/fat/protein macronutrients

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Function of Vitamins

• 1. Metabolism coenzyme needed for metabolism
• 2. Tissue Bone building
• 3. Prevention of deficiency diseases
• Scurvy, beri beri, pellagra

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VitaminsClasses

• Fat soluble (vit. A,D,E,K)
• Best absorbed when eaten with fat
• May be stored for long periods in liver and
  adipose tissue
• ie Vit A best absorbed w/ whole milk
• Water soluble (vit. B,C, folate)
• Easily absorbed by intestinal cells and
  transported by the portal (liver) circulation
• Not stored, so must be eaten on regular basis

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Fat-Soluble VitaminsVitamin A

• Functions
• Vision (healthy retina, prevent macular
  degeneration)
• Immunity (production of immune cells, fight
  infection)
• Growth (of muscle and soft tissue)
• Deficiency Night Blindness
• Toxicity symptoms IU 3000mcg/day, liver damage,
  joint pain, headaches
• Food sources Liver, egg yolk, milk fat, butter
• Stability cooking veggies can inactivate vit A
• best absorption w/ fat

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Vitamin D

• Functions
• Absorption of calcium and phosphorus
• Bone mineralization
• Requirements none if exposed to sun
• Deficiency Rickets (malformation of long bones
  in kids) and osteoporosis
• Deficiency rare milk is fortified w/ Vit. D
• Toxicity unusual, kidney damage
• Food sources Milk, margarine

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Vitamin D

• OTC vitamin D (ie Caltrate w/ D)
• From a plant source
• Humans lack enzyme needed to adequately absorb
  vit. D
• We only absorb about 1
• Rx vit. D much more effective Drisdol
• given orally, weekly or monthly
• recommended for US residents living north
  of
• Virginia, less daily sunshine
• Kidneys must activate Vit. D
  first

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Child with Rickets
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Vitamin E

• Functions
• Antioxidant (prevents oxidation of molecules
  prevents free radicals from changing healthy
  cells, accepts oxygen)
• Deficiency Hemolytic anemia (breakdown of RBC),
  premature infants
• Toxicity none
• Food sources vegetable oils, nuts, avocado,
  fortified cereals

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Vitamin K

• Functions
• Blood clotting
• Bone development
• Requirements intestinal bacteria produces vit. K
  
• Deficiency Uncommon, newborns, long term
  antibiotic use
• Toxicity none
• Food sources green, leafy vegetables
• Spinach, broccoli, turnip greens)

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Water-Soluble Vitamins Vitamin C (Ascorbic
Acid)

• Functions
• Build connective tissue (collagen)
• Antioxidant function (protect from free rad.)
• Helps w/ absorption of iron
• NOT truly proven to treat colds URIs
• Requirements More w/ preg, lactation, smokers
• Deficiency Scurvy
• Toxicity tissue, gum bleeding, soft teeth, poor
• wound healing
• Food sources strawberries, melon, oranges,
• tomato, broccoli, potato, peppers,
  cabbage

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Thiamin (Vitamin B1)

• Functions needed for utilization of energy,
  helps metabolize carbohydrates
• GI system (normal appetite, digestion and
  elimination)
• CNS (alertness, normal reflexes)
• CV (normal function)
• Requirements increased in pregnancy
• Deficiency Alcoholism, Beriberi (CNS)
• Food sources beef, pork, enriched grains,
  legumes

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Riboflavin (Vitamin B2)

• Functions
• Energy production
• Tissue building
• Requirements increased w/ preg. lactation
• Deficiency usually occurs with protein
  malnutrition
• Toxicity none
• Food sources Milk !

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Niacin (Vitamin B3)

• Functions
• Energy production (extracts energy from CHO, fat,
  prot.)
• Helps to improve lipid levels
• Requirements higher w/ preg., lact.
• Deficiency Pellagra (4 Ds)
• Toxicity from supplements reddened skin w/
  itching and burning
• Food sources meat, poultry, fish, whole grains

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Niacin Defeciency

• 4 Ds

• Pellegra

• Dermatitis
• Diarrhea
• Dementia
• Death

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Folate

• Functions
• Regulation of blood homocysteine levels high
  levels can cause CV disease !
• Reduces likelihood of neural tube defects in
  unborn
• Requirements 400 mcg/day. Pregnant women, women
  of child bearing age should take in dietary form
  supplements 600mcg/day
• Deficiency diseases Neural tube defects (spina
  bifida, anencephaly)
• Toxicity minimal, some nerve damage
• Food sourcesgreen leafy veg, beans, OJ

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Vitamin B12 (Cobalamin)

• Functions
• Regulation of blood homocysteine levels
• Hemoglobin production
• Nervous system functioning
• Requirements higher w/ preg, lact.
• Deficiency Pernicious anemia (irreversible nerve
  damage)
• Toxicity none
• Food sources lean meats, clams, oysters, crab

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Vitamin Supplementation

• Ongoing debateyes or no ??
• Biochemical individuality the bodys chemical
  composition varies for each person, this also
  changes based upon
• Life cycle needs
• Pregnancy and lactation (folic acid )
• Infancy (vit K at birth)
• Children and adolescents (rapid growth)
• Aging (decreased food intake)

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Vitamin Supplementation, contd

• Lifestyle
• Oral contraceptive use (may lack B C)
• Restricted diets (vegetarians may lack B12)
• Exercise programs (may need more riboflavin)
• Smoking (need more vit. C)
• Alcohol (thiamin, folate)
• Caffeine (4-6 c/day coffee diuretic effect
  may lack Bs)
• Disease (increased nutrient needs)

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Vitamin Supplementation, contd

• Megadoses
• Toxicity megadose of fat soluble vitamins (vit.
  A) - liver/brain damage fat sol. stored
  in body
• Vit. B6 - folate (over 5 gm/day) - severe nerve
  damage
• Vit. C (ascorbic acid) (over 2 gm/day) -kidney
  stones