The Vitamins
Chapter 10 & 11
The Water-Soluble Vitamins:
B and C
(there are 8 B Vitamins)
The Fat-Soluble Vitamins:
A, D, E, and K
What are Vitamins?
- small organic molecules
- essential nutrients
- required in very small quantities
e.g.
5 g / day of Vit D
400 g / day of folate
14 g / day of biotin
Compare this to the energy nutrients
Energy Nutrients
Assume a 2000 kcal / day diet
% Carbs:
% Lipids:
% Proteins:
?
?
?
Energy Nutrients
Assume a 2000 kcal / day diet
% Carbs: 55% x 2000 kcal = 1100 kcal
% Lipids: 30% x 2000 kcal = 600 kcal
% Proteins: 15% x 2000 kcal = 300 kcal
275 g Carbs, 67 g Lipids, 75 g Protein
What do Vitamins look like?
O
H3C
H3C
N
N
N
N
O
O
CHOH
CHOH
OH
O P O
O
CH2
CHOH
O
H
H
N
H
Riboflavin
(Vit. B2)
Pyridoxal phosphate
(Vit. B6)
CH2
OH
CH3
HO
O
HOCH2
HO
O
OH
Ascorbic Acid
(Vit. C)
What do Fat Soluble Vitamins look like?
H3C
CH3
CH3
CH3
OH
CH3
Retinol
(Vit. A)
H3C
CH3
H2C
Pre-Vit. D
HO
What do Vitamins actually do?
- they are co-factors or co-enzymes
- they help proteins perform various
functions within the body.
e.g.
- enzymes in energy metabolism
- vision (Vit. A)
Coenzyme Action
The Water-Soluble Vitamins:
B and C
Metabolic
pathways
involving B
Vitamins
Getting Proper Levels of Vitamins
If the guidelines of diet-planning are
followed, individuals in the developed world
should not have a problem.
However, there are things to consider:
1)
2)
3)
4)
Bioavailability
Stability
Solubility
Toxicity
Understanding Dose Levels vs Health Effects
The B Vitamins
- Thiamin
- Riboflavin
- Niacin
- Biotin
- Pantothenic acid
- Pyridoxine
- Folate
- Cyanocobalamin
Lets look at 2……
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Thiamin
Pork is the
richest source
of thiamin, but
enriched or
whole-grain
products
typically make
the greatest
contribution to
a day’s intake
because of the
quantities
eaten.
Thiamin (TPP) - Vit B1
- involved in the
conversion of pyruvate
to acetyl-CoA
- deficiency results
in a condition known
as beriberi
- damage to nervous
system, brain function,
heart and muscles.
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Folate
(Folic Acid)
Leafy green
vegetables,
legumes,
liver, and
some fruits
are
naturally
rich in
folate.
Folate (Folic acid)
- involved in the synthesis of DNA,
especially in newly formed cells
- deficiency results in anemia and GI
tract deterioration
- in the developing fetus, neural
tube defects have been linked to low
folate levels
Vitamin C (Ascorbic Acid)
When dietitians say “vitamin C,” people think
“oranges,” but these foods also are rich in vitamin
C.
Vitamin C (Ascorbic Acid)
- deficiency results in scurvy
- involved in the synthesis of
collagen
Ascorbic Acid
(Vit. C)
O
H2N
+
O
O
H2N
+
OH
O
2000
Vitamin C
RDA
(75 - 100 mg/day)
Linus Pauling
90
75
Common cold
And
Heart Disease
The Fat-Soluble Vitamins:
A, D, E and K
Forms of Vitamin A
OH
retinol
H
O
retinal
OH
O
retinoic acid
-carotene
Vitamin A Deficiency
- 100 million children worldwide suffer
from some form of Vit A deficiency
- Infectious Disease - Measles kills 2
million children each year
- Night Blindness and Xerophthalmia
- Keratinization
(RDA = 700 - 900 g / day)
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning ™ is a trademark used herein under license.
The
carotenoids in
foods bring
colors to
meals
….. the
retinoids in
our eyes
allow us to
see them.
Retinol’s Role in Vision
11-trans-retinal
11-cis-retinal
light
metarhodopsin-II
N
OPSIN
rhodopsin
N
OPSIN
retinal
isomerism
H
O
OPSIN
light
H
O
OPSIN
Vitamin D Deficiency
- rickets in children
- osteomalacia in adults leading to
osteoporosis
(AI = 5 g / day)
Vitamin D
synthesis
and
activation
Part from diet
Part from
biosynthesis
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Vitamin D synthesis and Latitude
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Vitamin D can be synthesized in the body with
the help of sunlight or obtained from foods
derived from animals. A deficiency causes
rickets in childhood. Fortified Milk is an
important food source.
Vitamin E Deficiency: a-tocopherol
- Primary deficiency is very rare
- Secondary deficiency:
(usually associated with a lack of fat absorption)
- Erythrocyte hemolysis
- Neuromuscular dysfunction
(RDA = 15 mg / day)
Free Radical Formation
e- 2 H+
e-
e- H+
.
O
O2
H2O2
2
.
protein
protein
or
lipids
(PUFA)
.
OH
+
.
OH
or
.
lipids
(PUFA)
+
H2O
Anti-oxidant Protection Against
Free Radicals
.
protein
or
protein
+ Vit. E
lipids .
(active)
(PUFA)
Vit. E
.
(inactive)
+ Vit. C
or
lipids
(PUFA)
Vit. E
(active)
+ Vit. E
.
(inactive)
+ Vit. C
Vitamin E Supplements
Vitamin E has 3 stereogenic centres
Therefore, when made synthetically:
2 x 2 x 2 = 8 different forms
ONLY 1 is the NATURAL & ACTIVE form
1 / 8th
Vitamin K Deficiency
- Primary deficiency is rare because it is
produced from bacteria in the GI.
- Secondary deficiency:
1) altered fat absorption
2) drugs such as antibiotics kill or
disrupt bacterial production of Vit. K
(AI = 90 - 120 g / day)
Vitamin K Deficiency
- Hemorrhagic disease
(uncontrolled bleeding)
- Bone Health - i.e. osteoporosis
(involved in the activation of 3 bone
health related proteins)
- Calcification of Arterial Plaques
(increased risks of heart disease
and arterial sclerosis)
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Notable food
sources of
vitamin K
include:
milk, eggs,
brussels
sprouts,
collards, liver,
cabbage,
spinach, and
broccoli.
Phytochemicals in Disease Prevention
Phytochemicals metabolites produced by plants
e.g.
1) Antioxidant activity
2) Phytosterols
Anti-oxidant Protection Against
Free Radicals
.
protein
or
.
lipids
(PUFA)
protein
+ Phyto
chemical
(active)
or
lipids
(PUFA)
.
Phyto
+
chemical
(inactive)
Phytochemicals in Disease Prevention
Broccoli Sprouts
Red Wine:
Resveratrol
Apples:
Flavonoids
Garlic & Onions:
Allicin (S)
Flax:
Lignan
Tomatoes:
Lycopene