Chapter 7
Vitamins
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

Key Concepts

Vitamins do not provide energy

Vitamins work as “coenzymes” to
activate other enzymes in the body
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
Era of Vitamin Discovery
Most vitamins discovered in early
1900’s
 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.
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

Function of Vitamins
1. Metabolism: coenzyme needed for
metabolism
 2. Tissue & Bone building
 3. Prevention of deficiency diseases

 Scurvy,
beri beri, pellagra
Vitamins:
Classes

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
Fat-Soluble Vitamins:
Vitamin 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
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
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
Child with Rickets
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
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)
Water-Soluble Vitamins:
Vitamin C (Ascorbic Acid)

Functions






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Build connective tissue (collagen)
Antioxidant function (protect from free rad.)
Helps w/ absorption of iron
NOT truly proven to treat colds & URI’s
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
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
Riboflavin (Vitamin B2)

Functions



Energy production
Tissue building
Requirements: increased w/ preg. &
lactation

Deficiency: usually occurs with protein
malnutrition
Toxicity: none
 Food sources: Milk !

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 D’s)
Toxicity: from supplements = reddened skin




w/ itching and burning

Food sources: meat, poultry, fish, whole
grains
Niacin Defeciency
4 D’s
 Dermatitis

Diarrhea

Dementia

Death
Pellegra
Folate

Functions


Regulation of blood homocysteine levels – high levels
can cause CV disease !
Reduces likelihood of neural tube defects in
unborn

Requirements:

Deficiency diseases: Neural tube defects
400 mcg/day. Pregnant women,
women of child bearing age should take in dietary form +
supplements = 600mcg/day
(spina bifida, anencephaly)


Toxicity: minimal, some nerve damage
Food sources–green leafy veg, beans, OJ
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
Vitamin Supplementation
Ongoing debate……yes or no ??
 Biochemical individuality: the body’s

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)
Vitamin Supplementation,
cont’d

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 B’s)

Disease (increased nutrient needs)
Vitamin Supplementation,
cont’d

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
