Download Chapter 7

Chapter 7
The Vitamins:
A Functional
Approach
Ask Yourself
True or False?
1. The most important role that vitamins play is
providing energy.
2. You can’t overdose on vitamins, because the
body excretes them in the urine.
3. Serving for serving, fruits and vegetables
tend to be the richest sources of vitamins.
4. Vitamin D is also known as the “sunshine
vitamin” because the body can make vitamin
D with the help of sunlight.
5. Vitamin C supplements prevent colds.
Ask Yourself
6. Several major public health associations
recommend that all adults take antioxidant
supplements.
7. Fresh vegetables contain more vitamins than
frozen vegetables.
8. Phytochemicals are beneficial nonnutrient
substances found in fruits, vegetables, and
whole grains.
9. In general, nutrients are absorbed equally as
well from foods as from supplements.
10. Maintaining a healthy weight may be one of
the most important ways to protect against
cancer.
Turning Back the Clock
Many vitamin deficiency diseases
have been eliminated today with the
discovery of vitamins.
• Scurvy
The vitamin C deficiency disease characterized by bleeding
gums, tooth loss, and even death in severe cases.
• Rickets
A disease that occurs in children as a result of vitamin D
deficiency and that is characterized by abnormal growth of
bone, which in turn leads to bowed legs and an outwardbowed chest.
• Pellagra
Niacin deficiency characterized by diarrhea, inflammation of
the skin, and, in severe cases, mental disorders and death.
The Vitamins
• Vitamin:
A potent, indispensable compound that
performs various bodily functions that
promote growth and reproduction and
maintain health.
 Vitamins are organic, meaning that
they contain or are related to carbon
compounds.
 Contrary to popular belief, vitamins do
not supply calories.
 They are essential to helping the body
make use of the calories consumed via
foods.
Two Classifications of Vitamins
Water-Soluble Vitamins
• Water-soluble vitamins act as coenzymes.
 Coenzymes
Enzyme helpers; small molecules that interact with
enzymes and enable them to do their work.
• Water-soluble vitamins are fragile:
 Can be washed out or destroyed during food storage,
processing and preparation.
Coenzyme
A
A
B
Enzyme
Without the coenzyme,
compounds A and B
don’t respond to the
enzyme.
AB
B
Enzyme
With the coenzyme in place, The reaction is completed.
A and B are attracted to the A new product, AB, has
active side on the enzyme, Been formed.
and they react.
Fat-Soluble Vitamins
• ADEK
• Absorbed from the digestive tract
with the aid of fats in the diet and
bile produced by the liver.
• Transported by protein carriers in
the bloodstream.
• Stored in the liver and body fat:
Do not need to consume daily.
Antioxidant Vitamins:
• Enhance the immune system
• Limit free-radical formation
• Destroy free radicals and prevent oxidative
damage to cells
• Reduce inflammation in blood vessel walls
• Vitamin C defends body cells and tissues
such as skin, lungs, and blood.
• Vitamin E and beta-carotene defend the
body’s lipids such as cell membranes and
lipoproteins.
The Antioxidant Vitamins
• Some chemical reactions in the
body involve the use of oxygen.
• These reactions create toxic
compounds called free radicals.
• These free radicals contribute to
cell damage and the development
of chronic diseases such as cancer
and heart disease.
Chronic disease (heart disease,
cancer) and aging
Damage cell
membrane lipids and proteins
Sunlight
Cigarettes
Free
Radicals
Damage
protein
enzymes
Alter cellular DNA
Oxidize
blood cholesterol
Environmental
pollution
Body
processes
The
Antioxidant
Team
Neutralize free
radicals
The Antioxidant Vitamins
• Antioxidant nutrients are the
body’s defense against free radical
damage.
• Antioxidant nutrients include:
Vitamin C
Vitamin E
The carotenoids—beta-carotene
Selenium - found in an enzyme that
helps to fight free radicals (Chapter 8)
The Antioxidant Vitamins
Vitamin C:
• Blocks free radical formation and along
with vitamin E may reduce heart
disease and cancer.
• Is a powerful scavenger of air
pollutants.
• Required for the production and
maintenance of collagen.
• Boosts the body’s ability to fight
infections.
The Antioxidant Vitamins
Vitamin C
• Potential role as a chronicdisease fighter stems from
its workings as an
antioxidant.
• Antioxidant: a substance,
such as a vitamin, that is
“anti-oxygen” – that is, it
helps to prevent damage
done to the body as a result
of chemical reactions that
involve oxygen.
• It’s role in preventing the
common cold is insignificant.
• Widespread in the food
supply but deficiencies do
occur.
The Antioxidant Vitamins
Sources of Vitamin C
Vitamin C is widespread in the food supply.
Deficiencies arise both in infants not given a
source of vitamin C and in children and the
elderly.
The Antioxidant Vitamins
Vitamin E
• Known as a vitamin in search of a
disease.
• Widespread in the food supply, and
deficiencies of the nutrient are rare.
• Performs a key role as an antioxidant in
the body.
 May protect membranes of the lungs,
heart, brain, and other organs against
pollutants and other environmental
hazards.
The Antioxidant Vitamins
Vitamin E
• People who run the
risk of deficiency:
 Premature infants who
are born before
vitamin E is
transferred to them
from their mothers.
 Those who cannot
absorb fats as a result
of diseases.
 Those with certain
blood disorders.
The Antioxidant Vitamins
The Antioxidant Vitamins
The Vitamin A Precursor: Beta Carotene
• Beta-carotene is a member of the
carotenoid family.
 The carotenoids possess antioxidant
properties.
 May help prevent age-related macular
degeneration and lower risk of cataracts.
• Beta-carotene: an orange pigment
found in plants that is converted into
vitamin A inside the body.
The Antioxidant Vitamins
Vitamin A
• One of the most versatile vitamins; plays
roles in several important body
processes.
• Best known function is in vision.
 Night blindness accompanies deficiency
• Helps to maintain healthy epithelial
tissue.
• Up to a year’s supply can be stored in
the body, 90% of it in the liver.
The Antioxidant Vitamins
• Deficiency symptoms appear after your
stores are depleted.
• Consequences include blindness and
reduced resistance to infection.
• Toxicity can pose a hazard for those
taking preformed vitamin A
(supplements).
• There is no toxicity risk for betacarotene.
The Antioxidant Vitamins
Sources of Vitamin A and Beta-Carotene
•The major sources of vitamin A are almost all
brightly colored hues of green, yellow, orange and
red.
•Vitamin A is measured in Retinol Activity
Equivalents (RAE). This is a measure of both
preformed vitamin A and beta-carotene in foods.
Vitamins for Healthy Blood
• The body needs a
continuous supply
of water, oxygen,
energy, and
building materials.
• Blood carries
oxygen and
nutrients to cells.
• Blood carries away
carbon dioxide and
waste products.
Vitamins for Healthy Blood
• Folate is needed for formation and
maintenance of healthy red blood cells.
• Vitamin B12 is needed for formation of
healthy red blood cells.
• Vitamin B6 is needed for synthesis of
hemoglobin, which carries oxygen in
the blood.
• Vitamin K is needed for blood clotting.
Vitamins for Healthy Blood
Folate
• Folic acid or folacin
• Coenzyme with many
functions in the body.
• Important in the synthesis
of DNA and the formation of
red blood cells.
• A deficiency makes the red
blood cells misshapen and
unable to carry sufficient
oxygen...
 Causing a certain kind of
anemia.
 Anemia: any condition in
which the blood is unable to
deliver oxygen to the cells
of the body.
Vitamins for Healthy Blood
Folate and Birth
Defects
• Plays a crucial role in a
healthy pregnancy.
• Reduces the risk of
bearing a baby with a
type of birth defect
called a neural tube
defect.
 Like spina bifida
Vitamins for Healthy Blood
Sources of Folate
The Food and Drug Administration has mandated
that all enriched grain products be fortified with
folic acid to improve intakes in the United States
population.
Vitamins for Healthy Blood
B Vitamins and Heart Disease
• Low intakes of folate, vitamin B12, and
vitamin B6 are linked to increased risk of
heart attack or stroke.
• Increased levels of homocysteine in
blood.
• Enhanced blood clot formation and
damage to arterial walls.
• Homocysteine may be toxic to the brain.
Vitamins for Healthy Blood
Vitamin B12
• Maintains the sheaths
that surround and
protect nerve fibers.
• Works closely with
folate, enabling it to
manufacture red blood
cells.
 A vitamin B12 deficiency
can prevent folate from
building healthy red
blood cells, resulting in
anemia.
 Treatment with folate
will cure the anemia but
mask the vitamin B12
deficiency.
Vitamins for Healthy Blood
Vitamin B12
• Deficiencies are unlikely for individuals
who consume animal-based foods.
• Some groups at risk of deficiency
include:
 Strict vegetarians.
 Those with a genetic defect that leaves
the body unable to make a compound
known as intrinsic factor.
 And those elderly who may develop
atrophic gastritis.
Vitamins for Healthy Blood
Sources of Vitamin B12
Vitamins for Healthy Blood
Vitamin B6
• Functions as a coenzyme.
• Helps make hemoglobin for red blood cells.
• Plays a role in protein metabolism.
 Requirements are proportional to protein
intake.
• Deficiency symptoms:
 Weakness
 Irritability
 Insomnia
Vitamins for Healthy Blood
Sources of Vitamin B6
Vitamins for Healthy Blood
Vitamin K
• Key function: its role in the bloodclotting system of the body.
• Works with vitamin D to help regulate
the calcium levels in the blood.
• Is obtained both in the diet and via the
intestinal bacteria, making deficiencies
rare.
 Newborn babies are the one group that
is commonly susceptible to a vitamin K
deficiency.
 A baby’s digestive tract is free of
bacteria until birth.
Vitamins for Healthy Blood
Sources of Vitamin K
Color Your Plate with
Vitamin Rich Foods
• Shop at least once a
week
• Store most fruits and
vegetables whole in
the frig
• Eat within a month
of purchase
• Cook in the least
amount of water and
for the shortest time
Vitamins for Healthy Bones
• Bones are made up of a matrix of living tissue
based on collagen, into which the crystals of
bone minerals are deposited.
 Calcium and phosphorus are the principle
bone minerals in the matrix.
 Bones undergo remodeling throughout life
but peak bone mass is reached at about 30
years of age.
• Vitamins essential for healthy bones:
 Vitamin D
 Vitamin K
 Vitamin B12
Vitamins for Healthy Bones
Electron micrograph of healthy
trabecular bone
Electron micrograph of trabecular
bone affected by osteoporosis
Vitamins for Healthy Bones
Bone Making and Maintenance Team
• Vitamin D directs the team consisting of:
Vitamins: vitamin C and vitamin K
Hormones
Protein: collagen
Minerals: calcium, phosphorus,
magnesium, and fluoride (Chapter 8)
Vitamins for Healthy Bones
Vitamin D
• Assists the absorption of
dietary calcium.
• Helps to make calcium
and phosphorus
available in the blood so
these minerals can be
deposited into bone.
• Acts much like a
hormone, exerting
influence on other
organs like kidneys and
the intestines.
Vitamins for Healthy Bones
Vitamin D
• Regardless of dietary
consumption, the body
can synthesize vitamin
D with the help of
sunlight.
• The liver makes a
vitamin D precursor and
with the help of the
sun’s ultraviolet rays, it
becomes an active form
of vitamin D.
Vitamin D is the sunshine vitamin
Vitamins for Healthy Bones
Vitamin D Deficiency:
• Needs can be met through
diet or sun exposure.
• Sun exposure of face, hands
and arms for 5-15 minutes
several times per week will
meet needs.
• Deficiency risk includes:
 Living in northern climate.
 Institutionalized or
housebound elderly people.
• Deficiency disease:
 In children, rickets.
 In adults, osteomalacia.
Bones become soft,
porous, and weak
Vitamins for Healthy Bones
Only a few foods contain vitamin D
Vitamins for Healthy Bones
Vitamin K
• Works in conjunction with vitamin
D to synthesize a bone protein that
regulates the calcium levels in the
blood.
• Low levels have been associated
with low bone mineral density and
hip fracture in older women
Vitamins for Energy Metabolism
• When the body needs energy it
breaks down glycogen to glucose,
triglycerides to fatty acids &
glycerol, or protein to amino acids.
• When the body does not need
energy, it builds glycogen, body
proteins, or body fat.
• Many vitamins and minerals are
essential for energy metabolism.
Vitamins for Energy Metabolism
•Thiamin
•Riboflavin
•Niacin
•Vitamin B6
•Folate
•Vitamin B12
•Pantothenic acid
•Biotin
Vitamins for Energy Metabolism
Thiamin
• One of the B vitamins.
• Acts primarily as a coenzyme in
reactions that release energy from
carbohydrate.
• Plays a crucial role in nerve processes
• Beriberi
The thiamin deficiency disease,
characterized by irregular heartbeat,
paralysis, and extreme wasting of
muscle tissue.
Vitamins for Energy Metabolism
Sources of Thiamin
Vitamins for Energy Metabolism
Riboflavin
• Also one of the B vitamins.
• Acts as a coenzyme in energy-releasing
reactions in the body.
• Helps to prepare fatty acids and amino
acids for breakdown.
• Deficiencies of the vitamin (rare), are
characterized by severe skin problems,
including painful cracks at the corners
of the mouth; a red, swollen tongue;
and teary or bloodshot eyes.
Vitamins for Energy Metabolism
Sources of Riboflavin
Vitamins for Energy Metabolism
Niacin
• Also one of the B
vitamins.
• Also part of a
coenzyme vital to
obtaining energy.
• Recall that
pellagra is the
deficiency
disease.
Vitamins for Energy Metabolism
• Can be made from
the amino acid
tryptophan in the
body.
• 60 milligrams of
tryptophan yield 1
milligram of niacin.
• Thus, the DRI for
niacin is expressed
in niacin equivalents
(NE).
Vitamins for Energy Metabolism
Sources of Niacin
Vitamins for Energy Metabolism
Pantothenic acid and biotin
• Both are B vitamins needed to
synthesize coenzymes that are active in
many body systems.
• Biotin is required for cell growth,
synthesis of DNA, and maintenance of
blood glucose levels.
• Both are widespread in foods, so people
who eat a varied diet are not at risk for
deficiencies.
Vitamins for Energy Metabolism
Sources of Biotin and Pantothenic Acid
Phytonutrients in Foods
Cruciferous vegetables, such as
cauliflower, broccoli, and Brussels
sprouts, contain nutrients and
nonnutrients that protect against
cancer.
• Phytochemicals
Physiologically active
compounds found in
plants that are not
essential nutrients but
that appear to help
promote health and
reduce risk for cancer,
heart disease, and
other conditions.
• Also called
phytonutrients.
 phyto = plant
Phytonutrients in Foods
Phytonutrients
• Give plants their brilliant colors and distinct
aromas
• Found in edible parts of plants including fruits,
vegetables, & whole grains.
• They do not provide energy or building
material.
• Ongoing research indicates they act as
powerful antioxidants, decreasing blood
pressure & cholesterol, preventing cataracts,
reducing menopause symptoms & risk for
osteoporosis, & slowing or reversing certain
cancers.
Phytonutrients in Foods
Phytonutrients
• Many foods contain numerous phytochemicals,
each one acting on one or several
mechanisms.
 Antioxidant properties - protect against
harmful cell damage.
 Anticancer properties - preventing initiation
and promotion of cancer.
 Anti-estrogen properties - blocking action of
estrogen and lowering risk of some cancers.
 May protect against other diseases
 Heart disease, eye disease, osteoporosis and
cancer
Phytonutrients in Foods
Optimizing Intake of Phytochemicals
• Pure extracts in supplements are less effective
than phytochemicals in whole food.
• Absorption, metabolism, distribution, and
function depends on the combination of
phytochemicals and other substances naturally
occurring in food.
• Until more is known, it is best to follow
recommendations of MyPlate for fruit,
vegetables, whole grains, soy foods, legumes,
nuts, and seeds.
Choosing a Vitamin-Mineral Supplement
• Remember most
people should be
able to get all
needed nutrients
from diet
• Particular groups
of people may
need
supplementation
Keep these points in mind when
choosing a supplement
1. Remember that price is not an
indication of quality.
2. Look for a supplement that contains
both vitamins and minerals, with no
more than 100 percent to 150 percent
of the recommended Daily Values for
each.
3. Buy products sold in childproof bottles
or packages if you have children
around.
Nutrition & Cancer Prevention
Genetic and related risk factors (Total) 14%
Family history of cancer 5%
Perinatal factors/growth 5%
Reproductive factors 3%
Prescription drugs/medical procedures 1%
Environmental
risk factors
(Total) 9%
Viruses/other
biologic agents 5%
Pollution 2%
Ionizing/ultraviolet
radiation 2%
Lifestyle risk factors (Total) 77%
Tobacco use 30%
Adult diet/obesity 30%
Sedentary lifestyle 5%
Occupation/job-related factors 5%
Alcohol 3%
Socioeconomic status 3%
Salt/food additives, and other
preservatives/contaminants
1%
Cancer initiation: Initiation by a carcinogen causes
cancerous alterations in previously healthy body cells.
Examples of Carcinogens
A. Cancer initiation. Initiation by a carcinogen causes cancerous alterations in
previously healthy body cells.
Ultraviolet light/
radiation
Cigarettes
Healthy
body cells
Toxic environmental
pollution/contaminants
Damaged cellular Development of
DNA and altered cancerous cells
genetic material
Cancer promotion: Cancer promoters enhance the
growth of abnormal cancerous cells.
B. Cancer promotion. Cancer promoters enhance the growth of abnormal
cancerous cells.
Cancerous cells
Cancer progression
Examples of Cancer Promoters:
Ultraviolet
light/radiation
Cigarettes
Toxic environmental
pollution/contaminants
Excess alcohol
Lack of physical
activity and obesity
Excess dietary fat
Cellular repair: Cancer antipromoters squelch free
radical damage and enhance the body’s ability to
repair damaged DNA strands.
C. Cellular repair. Cancer antipromoters squelch free radical damage and
enhance the body’s ability to repair damaged DNA strands.
Damaged cellular
DNA and altered
genetic material
Healthy
body cells
Examples of Cancer Antipromoters:
The antioxidant, fiber,
and phytochemical team
Strong immune system
and healthy body weight
Factors that Decrease or Increase Cancer Risk
Nutrition & Cancer Prevention
1. Be as lean as possible without becoming
underweight.
2. Be physically active for at least 30 minutes
every day.
3. Avoid sugary drinks. Limit consumption of
energy-dense foods
4. Eat more of a variety of vegetables, fruits,
whole grains, and legumes such as beans.
5. Limit consumption of red meats (such as
beef, pork, and lamb) and avoid processed
meats.
Nutrition & Cancer Prevention
6. If you do drink alcohol, limit your
consumption to no more than two drinks a day
for men and one drink a day for women.
7. Limit consumption of salty foods and foods
processed with salt (sodium).
8. Don’t use supplements to protect against
cancer.
9. And always remember—do not smoke or chew
tobacco.