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Diet and Health
Introduction
2 main kinds of diseases afflict
people worldwide:
• Infectious diseases
– Diseases that are caused by bacteria, viruses,
parasites, and other microbes
– Can be transmitted from one person to another
through air, water, food or contact; or through
vector organisms such as mosquitoes and fleas
• Degenerative diseases
– Chronic, irreversible diseases characterized by
degeneration of body organs
– Due in part to such personal lifestyle elements as
poor food choices, smoking, alcohol use, and lack
of physical activity
– Also called lifestyle diseases, chronic diseases, or
the diseases of age
2
Introduction
• Infectious diseases have been major
killers of humankind since before the
dawn of history
– In any society not well defended against
them, infectious diseases can cut life short
so that people die at 20, 30, or 40 years
of age
• With the advent of vaccines and
antibiotics, people in developed
countries had become complacent
about infectious diseases - until the
threat of bioterrorism became an
issue.
3
Introduction
• Individuals can take steps to protect
themselves from disease
– Although nutrition cannot directly prevent or
cure infectious diseases, it can strengthen or
weaken your body’s defenses against them
•“immune-strengthening” foods, dietary
supplements, and herbs are hoaxes
•The best help you can provide your
immune system is to nourish it properly to
ensure that it works to its capacity every
day
4
•In developed nations, degenerative diseases far outrank
infections as the leading cause of death and illness
•The longer a person lives, the more likely to occur!
5
Introduction
• Degenerative diseases do not arise
from a straightforward cause such as
infection
– But from a mixture of three factors
• Genetic predisposition
• Personal medical history
• Lifestyle choices
– As people age, their bodies accumulate
the effects of the lifestyle choices
• In the later years these impacts can make the
difference between a life of health or one of
chronic disability
6
Nutrition and Immunity
• Deficient intakes of many vitamins and
minerals are associated with impaired
disease resistance
– As are some excessive intakes
• Immune tissues are among the first to be
impaired in the course of a nutrient
deficiency or toxicity
• Some deficiencies are more immediately
harmful than others
– The speed of the impact is affected by
• Whether another nutrient can perform some of
the metabolic tasks of the missing nutrient
• How severe the deficiency is
• Whether an infection has already taken hold
• The person’s age
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Nutrition and Immunity
• Once a person becomes
malnourished, malnutrition
often worsens disease, which,
in turn, worsens malnutrition
• The cycle often begins when
impaired immunity opens the
way for disease
– The disease impairs food
assimilation, and nutrition
status suffers further
– Drugs become necessary, and
many of them impair nutrition
status even further
– Treatments, such as surgery,
take a further toll
– Young, old, sick, poor,
hospitalized most susceptible
8
Nutrition and Immunity
• Malnutrition can result not only from a
lack of available food but also from
diseases, such as AIDS and cancer,
and their treatments
• These conditions alter the appetite and
metabolism
– Causing a wasting of the body’s tissues
similar to that seen in the last stages of
starvation
– The body uses its fat and protein reserves
for survival
9
Lifestyle Choices and Risks of Degenerative
Disease
• Degenerative diseases of adulthood
have suspected contributors known as
risk factors
– Factors known to be related to (or
correlated with) diseases but not known to
be causal
• Environmental factors
• Behavioral factors
• Social factors
• Genetic factors
10
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Many of these conditions are also risk factors for
other degenerative diseases
Note: Obesity is linked to all of the
degenerative diseases
12
Lifestyle Choices and Risks of Degenerative
Disease
• The exact contribution diet makes to each
disease is hard to estimate
– Many experts believe that diet accounts for
about a third of all cases of coronary heart
disease
– The links between diet and cancer incidence
are harder to pin down
• Some choices, such as avoiding tobacco, are
important to almost everyone’s health
• Other choices, such as those relating to diet,
are more important for people who are
genetically predisposed to certain diseases
– Be aware of family medical history and own
blood work values
13
Cardiovascular Diseases
• Worldwide, CVD accounts for more deaths
among people of developed nations yearly
than any other single cause
• Not just for men, as more women die of
yearly of CVD than men; first time heart
attacks for women more likely to be fatal
• Atherosclerosis
– The most common form of cardiovascular
disease
– Characterized by plaques along the inner
walls of the arteries
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• No one is free of
atherosclerosis
– The question is how far
advanced it is and what you
can do to retard or reverse it
– Usually begins with the
accumulation of soft, fatty
streaks along the inner walls
of arteries, especially at
branch points
– These gradually enlarge and
become hardened fibrous
plaques (lipids mixed with
smooth muscle and
calcium
Cardiovascular
Disease
• Plaques damage artery
walls
– Making them inelastic
– Narrowing the passage
through them
– Most people have welldeveloped plaques by the time
they reach age 30
15
Cardiovascular Diseases
What causes plaque formation?
• A diet high in saturated fat is a major
contributor to the development and
progression of the disease
• Atherosclerosis-Damage may begin from a
number of factors interacting with the cells
that line the arteries and produce
inflammation
• High LDL cholesterol
• Hypertension
• Toxins from cigarette smoking
• Elevated blood levels of the amino acid
homocysteine-causes inflammation
• Or some viral and bacterial infections
16
Cardiovascular Diseases
• Normally, the arteries expand with each
heartbeat to accommodate the pulses of
blood that flow through them
– Arteries hardened and narrowed by
plaques cannot expand
– So blood pressure rises
– The increased pressure damages the
artery walls further and strains the heart
• Because plaques are more likely to form at
damaged sites, the development of
atherosclerosis becomes a self-accelerating
process
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Cardiovascular Diseases
• As pressure builds up
in an artery, the
arterial wall may
become weakened
and balloon out,
forming an aneurysm
(brain, abdomen)
– An aneurysm can burst
• In a major artery, such
as the aorta, the leads
to massive bleeding and
death
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Cardiovascular Diseases
• Abnormal blood clotting can also
threaten life
– Arterial damage, plaques in the arteries,
and the inflammatory response favor the
formation of blood clots
• Platelets normally cause clots to form
when they encounter injuries in blood
vessels
• In atherosclerosis, when platelets
encounter hardened plaques, they
respond to them as to an injury - clotting
blood
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Cardiovascular Diseases
• A clot may remain
attached to a plaque in
an artery and grow
until it shuts off the
blood supply to the
surrounding tissue
– That tissue may die
slowly and be replaced
by nonfunctional scar
tissue
– The stationary clot is
called a thrombus
-If it grows large enough
to close off artery,
called thrombosus
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Cardiovascular Diseases
• A clot can break loose becoming an
embolus
– Which travels along the system until it
reaches an artery too small to allow for its
passage
– There the clot becomes stuck and is
referred to as an embolism
• The tissues fed by this artery will be robbed of
oxygen and nutrients and will die suddenly
• Such a clot can lodge in an artery of the heart,
causing a heart attack, or lodge in an artery
of the brain, causing a stroke
21
Cardiovascular Diseases
• Opposing the clot-forming actions of platelets
are active products of omega-3 fatty acids
– A diet lacking in seafoods that contain these
essential fatty acids may contribute to clot
formation
• Occasionally, heart attacks and stroke occur
without apparent blockage and are due to a
spasm of the artery
• Arterial spasms may be caused by:
– Taking certain drugs, such as cocaine
– Emotional stress
– Exposure to cold
– Cigarette smoking
22
Cardiovascular Diseases
• Hypertension
– Hypertension worsens atherosclerosis because a
stiffened artery, already strained by each pulse of
blood surging through it, is stressed further by
high internal pressure
• Injuries multiply, more plaques grow, and more
weakened vessels become likely to burst and bleed
– Since hardened arteries cannot expand, the
heart’s beat raises blood pressure
– Hardened arteries also fail to let blood flow freely
through the kidneys, which control blood
pressure
• The kidneys sense the reduced flow of blood and
respond as if the blood pressure were too low
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Major Risk Factors for Heart Disease
Factors which can be modified include:
•
•
•
•
•
•
•
Poor lipid profile (low HDL, High LDL, High TG)
High blood pressure
Diabetes
Obesity
Physical inactivity
Cigarette smoking
Atherogenic diet (too much saturated/trans fat and
too little fruits, vegetables, whole grains)
Factors that cannot be modified:
Aging, male gender, family history of early heart
disease
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Risk Factors for CVD
• Age, Gender, and Family History
– The increasing risk associated with
growing older reflects the steady
progression of atherosclerosis in most
people as they age
• Men: age becomes a significant risk factor for
heart disease at age 45 or older
• Women: age becomes a significant risk factor
after age 55 when estrogen levels decrease
• Family history
– Early heart disease in immediate family
members is a major risk factor
25
Risk Factors for CVD
HDL and LDL factors:
– LDL carry cholesterol to the cells
• Including the cells that line the arteries where
it can build up as part of the plaques of
atherosclerosis
– HDL carry cholesterol away from the cells to the
liver for other uses and disposal
• Elevated HDL indicates a reduced risk of
atherosclerosis and heart attack
• With growing evidence that it may prevent
stroke as well
– High LDL and low HDL correlate directly with
heart disease
– Low LDL and high HDL correlate inversely with
risk
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Risk Factors for CVD
• How elevated LDL increases the risk of
heart disease remains unclear
– One mechanism may be through reducing
plaque stability
• As LDL is incorporated into plaques, the
plaques weaken and become unstable
• When this happens, they can rupture, causing
heart attack
• In advanced atherosclerosis, a goal of
treatment is to lower LDL cholesterol to
stabilize existing plaques while slowing the
development of new ones
27
Risk Factors for CVD
• Hypertension
– Chronic hypertension worsens CVD
• The higher the blood pressure above normal,
the greater the risk of heart attack or stroke
• The relationship between hypertension and
disease holds for
– Men and women
– Young and old
• Hypertension injures the artery walls and
accelerates plaque formation
– Initiating or worsening the progression of
atherosclerosis
28
Risk Factors for CVD
• Diabetes
– A major independent risk factor for all forms of
cardiovascular disease
– In diabetes, atherosclerosis progresses rapidly
• Blocking blood vessels and diminishing
circulation
– For many people with diabetes, the risk of a
future heart attack is roughly equal to that of a
person with a confirmed diagnosis of heart
disease
• 2x-4x as high as that of a person without
diabetes
– When heart disease occurs in conjunction with
diabetes, the condition is likely to be severe 29
Risk Factors for CVD
• Obesity and Physical Inactivity
– Obesity, especially central obesity, and physical
inactivity amplify a person’s risk of CVD
•
•
•
•
Elevates LDL cholesterol
Lowers HDL cholesterol
Worsens hypertension
Worsens diabetes
• Weight loss and physical activity
–
–
–
–
Lower LDL
Raise HDL
Improve insulin sensitivity
Lower blood pressure
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Risk Factors for CVD
• Routine physical activity
– Strengthens all muscles, including heart
– Improves the heart’s response to everyday
demands
– Stimulates the development of new arteries
to nourish heart muscle
– Favors lean over fat tissue
– Only 30 minutes of light, balanced exercise,
performed at intervals throughout the day,
can improve the odds against heart disease
• An hour a day, as recommended by the DRI,
benefits the heart even more
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Risk Factors for CVD
• Smoking
– Cigarette smoking is a powerful risk factor for heart disease
and other forms of CVD
– Smoking damages the heart directly with toxins and
burdens it by raising the blood pressure.
• Deprives the heart muscle of the oxygen it needs to
maintain a steady beat
• Damages platelets
– Making blood clots likely
• Toxins in cigarette smoke directly damage the lining
of blood vessels making atherosclerosis more likely
• When people quit smoking the risk of heart disease
begins to drop within a few months
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Risk Factors for CVD
• A well-chosen diet often lowers the risk
of CVD
– Does so to a greater degree than might be
expected from its effects on blood lipids
alone
– Factors that might take credit
•Vitamins
•Minerals
•Antioxidant phytochemicals
•Omega-3 fatty acids
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Diet to Reduce CVD Risk
• Diet’s effects are felt in two opposing ways
– A diet high in saturated fat and trans fatty acids
contributes to high blood LDL cholesterol
(promotes plaque instability)
– Reducing those fats in the diet lowers blood LDL
cholesterol and may reduce the rate of CVD
34
Diet to Reduce CVD Risk
• Controlling Dietary Lipids
– Lowering intakes of saturated fat and trans fat
lowers blood LDL cholesterol and reduces heart
disease risk
• Other authorities recommend: no more than
30% of total calories from fat
• DRI recommendations: the diet should contain
no more that 35% of total calories from fat
• Healthy people should limit cholesterol
intake to 300 mg a day (one egg yolk has
200-250 mg cholesterol)
– Although cholesterol plays a lesser role than
saturated fat and trans fatty acids, it still elevates
blood cholesterol
35
Diet to Reduce CVD Risk
• Strictly limiting all kinds of dietary fats
is probably not necessary to maintain
the health of the heart
– As long as the diet is low in saturated fat
and trans fat, energy intake is controlled
– The diet is ample in fish, fruit, vegetables,
and low fat milk products
• It matters what people choose to eat
instead of saturated fats
– Simple carbohydrates seem to elevate
blood triglycerides and reduce HDL
cholesterol
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Fish oils:
– Rich in omega-3
polyunsaturated fatty acids
Diet to Reduce
CVD Risk
– Lower triglycerides
– Prevent blood clots
– May reduce the sudden
death associated with CVD
-Other rich sources of omega3 fatty acids include:
walnuts, flaxseed, high
omega-3 fatty acid eggs,
canola and soybean oil
37
Diet to Reduce CVD Risk
• Effects of Fiber, Nutrients, and Phytochemicals
– The soluble fiber of oats, barley, legumes, and
pectin-rich fruits and vegetables helps to improve
blood lipids
• These fibers bind cholesterol and bile in the intestine,
reducing their absorption; 5-10 gms of soluble fiber
decreases cholesterol levels by about 5%
– A high-fiber diet may reduce a blood marker of
inflammation thought to indicate an elevated risk
of having a heart attack (C reactive protein)
– Foods rich in viscous or soluble fiber provide
antioxidants and helpful minerals to help protect
38
against LDL oxidation
Diet to Reduce CVD Risk
• Alcohol
– Research on middle-aged and older people
who drink one or two drinks a day with no
binge drinking supports the idea that
moderate consumption of alcohol will
reduce their CVD risk
• For this group, moderate alcohol consumption
has been reported to raise HDL cholesterol
levels or reduce the risk of blood clots
• May also raise triglyceride levels
• Heavy alcohol use, more than three
drinks a day:
– Elevates blood pressure, damages heart
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muscle, elevates risk of stroke
Diet to Reduce CVD Risk
Other Dietary Factors
Sterol and stanol esters
• Block absorption of cholesterol from the
intestine
• Dropping blood cholesterol by about
7%-10%
• The effect may be as powerful as some
medication in lowering blood LDL
cholesterol
• Sterol and stanol esters reduce the
absorption of some potentially beneficial
phytochemicals
• Use may be best reserved for
those who fail to lower their
elevated cholesterol by other
means
40
41
Diet to Reduce CVD Risk
• Diet and exercise form a powerful and safe
combination for improving health
• Needed weight loss often reduces blood
pressure
• So does eating a diet
– Low in fat
– Restricted in cholesterol
– High in complex carbohydrates, whole
grains, fruits, and vegetables
– Normalizes blood glucose
• More Strategies against CVD
– Don’t smoke and relax
42
Nutrition and Hypertension
• Chronic high blood pressure
(hypertension) remains one of the
most prevalent forms of CVD
– Affecting almost one-third of the entire
U.S. adult population
• For people age 65 or older, the lifetime risk of
developing it approaches 90%
– Contributes to half a million strokes and
over a million heart attacks each year
– Especially threatening when paired with
atherosclerosis
43
Nutrition and Hypertension
• Blood pressure-120/80
• 120 - (systolic-highest pressure during contraction
of left ventricle)
80 - (diastolic-lowest arterial pressure during
relaxation or between beats)
• Ideal resting blood pressure is 120/80
• High blood pressure presents no symptoms you can
feel-”Silent Killer”
– A reading of 130/85 can be considered borderline
normal
– Above this level the risks of heart attacks and
strokes rise in direct proportion to increasing
blood pressure
44
Role of kidneys in blood pressure control…
• For the kidneys to filter waste materials out of
the blood and into the urine, blood pressure
must be high enough to force the blood’s fluid
out of the capillaries into the kidneys’ filtering
networks
• If the blood pressure is too low, the kidneys act
to increase it, sending hormones to constrict
blood vessels and retain salt and water
• Atherosclerosis fools kidneys, which perceive
the body is water deficient when it may not be
• The kidneys raise the blood pressure high
enough to get the blood they need but too high
for the arteries and heart to withstand long term
45
How Does Blood Pressure Work in the Body…
• Risk factors that precipitate or aggravate
hypertension:
– Atherosclerosis-kidneys try to compensate
– Obesity (especially central obesity); for each 2.2
pounds of fat on your body, you add about 400
miles of additional blood vessels. These miles of
blood vessel promote more vascular resistance
which promotes higher blood pressure.
– Insulin resistance-increases obesity
– Age-Frequently occurs at 50-60 years of age
– Genetics-family history or African American race
46
How Does Nutrition Affect Hypertension?
• Nutrition factors for lowering blood pressure
– Lowering sodium intake
– If overweight, lose weight; control fat intake
– Using moderation with regard to alcohol
– Increasing intakes of fruit, vegetables, fish,
and low-fat dairy products
– Calcium, potassium, magnesium, and other
nutrients seem to play roles
• Translates to:
– Control weight
– Consume a nutritious diet
– Exercise regularly
– Control alcohol intake
– Hold sodium intake to prescribed levels
47
How Does Nutrition Affect Hypertension?
• DASH (Dietary
Approaches to Stop
Hypertension)
– Recommends significant
increases in fruit and
vegetable intakes
– Provides 30% of its
calories from fat
– Emphasizes legumes
over red meats
– Restricts sodium
– Meets other
recommendations of the
Dietary Guidelines for
Americans
DASH plan consistently
improves blood pressure
48
How Does Nutrition Affect Hypertension?
• Weight Control and Physical Activity
– For people who are overweight and hypertensive,
a weight loss of as little as 10 pounds can
significantly lower blood pressure
– Those who are taking medication to control their
blood pressure can often cut down on their doses
if they lose weight
• Moderate physical activity (walking, jogging)
– Helps in weight loss
– Redistributes body water
– Changes the hormonal climate in which the body
does its work
• By reducing stress, physical activity reduces
the secretion of stress hormones
• This lowers blood pressure
49
How Does Nutrition Affect Hypertension?
• Salt, Sodium, and Blood Pressure
– A high dietary intake of salt and sodium is
associated with hypertension
– The benefit of reducing salt intake in the
treatment of hypertension is unquestionable
• Reducing sodium and salt may also prevent
hypertension in healthy people
– People who consistently consume diets low in
sodium have lower blood pressure than people
with higher intakes
– Recommendation: everyone should moderately
restrict salt and sodium intake to a level not
exceeding the DRI committee’s UL
• No more than 2,300 mg of sodium per day
50
How Does Nutrition Affect Hypertension?
• Alcohol
– In moderate doses, alcohol initially relaxes
the peripheral arteries and so reduces
blood pressure
• High doses raise blood pressure
– Hypertension is common among people
with alcoholism
• Is apparently caused directly by the alcohol
• Alcohol may cause strokes
– Even without hypertension
51
How Does Nutrition Affect Hypertension?
Calcium, Potassium, Magnesium, and Vitamin C
– Increasing calcium often reduces blood pressure in
both healthy people and those with hypertension
– Diets low in potassium are often associated with
hypertension and high potassium diets seem to
prevent and correct hypertension
– Magnesium deficiency causes the walls of arteries
and capillaries to constrict and so may raise blood
pressure
– Consuming a diet adequate in vitamin C seems to
52
help normalize blood pressure
How Does Nutrition Affect Hypertension?
• To get all of the nutrients needed to keep
blood pressure low
– Consume a low-fat diet with abundant fruits,
vegetables, and low-fat dairy products that
provide the needed nutrients while holding
sodium intake in bounds
– DASH diet
• Reduces blood pressure
• May lower blood cholesterol
• Should diet and exercise fail to reduce blood
pressure, drugs such as diuretics or other
medications may be prescribed
– Diuretics work by increasing fluid loss in the
urine which also increases potassium excretion
- Need to consume extra potassium rich foods
53
Nutrition and Cancer
• Cancer ranks second only to heart disease as a
leading cause of death and disability in the
U.S.
• Inherited tendencies exert only a modest
effect on most people’s risk of cancer
development
– Very few rare cancers are known to be caused by genetic
inheritance alone
• 20%-50% of total cancers are influenced by
diet (Dietary fat, alcohol, excess calories, and low
intakes of fruits and vegetables have been
implicated in research studies)
• Most often lifestyle and environmental factors
come into play in the development of cancer
54
(smoking, diet, obesity)
Nutrition and Cancer
Physical activity and cancer:
• Restricting energy intake seems to limit
cancer
• Physical activity that can balance energy
intake may lower risk of developing cancer
• People whose lifestyles include regular,
vigorous physical activity have the lowest
risk of colon cancer
• Physical activity may also protect against
breast cancer by reducing body weight and
55
by other mechanisms
How Does Cancer Develop?
• Cancer is really a disease of the genes
– Cancer begins with one healthy cell whose genetic material
sustains damage from a carcinogen such as a free-radical
compound, radiation or other influence
• Damage to a cell’s DNA occurs every day
– But most of the damage is quickly repaired
– Sometimes DNA collects bits of damage here and there
over time
– If the damage cannot be repaired the cell may self destruct
• Occasionally, a damaged cell loses its ability to self
destruct also loses the ability to stop reproducing;
at this point millions of cancer cells form a tumor
which can be life threatening if it takes over a
56
healthy organ
How Does Cancer Develop?
Cancer develops through the following steps
1) Exposure to a carcinogen
2) Entry of the carcinogen into a cell
3) Initiation of a cancer as the carcinogen
damages or changes the cell’s genetic
material (Carcinogenesis)
4) Acceleration by other carcinogens, called
promoters, so that the cell begins to
multiply out of control - tumor formation
5) Often, spreading of cancer cells via blood
and lymph (metastasis)
6) Disruption of normal body functions
57
(Some compounds in
foods may stop the
process of feeding the
malignancy)
Other
carcinogens
Exposure
Initiation
Promoters
Cancerous tumor
entry of
by carcinogen enhance
releases cells into
carcinogen
that damages
tumor
the bloodstream
cell DNA
development
58
Researchers think steps 1-4 are key to
prevention
1) Exposure to a carcinogen
2) Entry of the carcinogen into a cell
3) Initiation of a cancer as the carcinogen
damages or changes the cell’s genetic
material (Carcinogenesis)
4) Acceleration by other carcinogens, called
promoters, so that the cell begins to
multiply out of control - tumor formation
5) Often, spreading of cancer cells via blood
and lymph (metastasis)
6) Disruption of normal body functions 59
Which Dietary Factors Most Influence A
Person’s Risk…
• Under study for possible effects
regarding cancer are
–
–
–
–
–
Excess calories-cancer rates increase
Diets high in certain fats
Daily use of alcohol
Vitamins and minerals in foods
Diets in which meat plays a dominant
role
60
Which Dietary Factors Most Influence A
Person’s Risk…
• In studies of human beings evidence
is mixed as to whether a diet high in
fat promotes cancer
– World population data reveal that highfat diets often correlate with high cancer
rates
• Studying the effects of high fat
intakes in complicated
– Because fat is extremely calorie dense
– Researchers must untangle the effects of
fat alone from those of the energy
61
content of the diet
Which Dietary Factors Most Influence A
Person’s Risk…
• The type of fat in the diet may be
important
– Some evidence implicates omega-6
polyunsaturated fatty acids in cancer
promotion
– Some evidence suggests that omega-3
fatty acids from fish may protect against
some cancers and may support recovery
during treatment for cancer
• Moderation in fat intake and inclusion
of several fish meals a week remain
sound principles
62
Which Dietary Factors Most Influence A
Person’s Risk…
•
Alcohol
-Cancers of the head, neck, breast correlate
strongly with alcohol intake
•
Smoked, Grilled, and Well-Done Meats
-Chemical reactions during browning of meat
at high temperatures form known
carcinogens
•
Acrylamide (French fries)
-Produced when carbohydrate rich foods are
cooked at high temperatures
63
Which Dietary Factors Most Influence A
Person’s Risk…
•
•
Fiber
–
–
Epidemiological studies often report links
between eating plenty of fruits and vegetables
and a low incidence of many cancers
Fiber rich foods are source of phytochemicals
A prominent theory is that a fiber-rich diet
may protect against some cancers by:
–
–
–
increasing stool weight and diluting the colon’s
contents
stimulating bacterial fermentation which
nourishes colon cells
and speeding up the transit time of materials
through the colon thus minimizing exposure of
the colon walls to cancer-causing substances in
the feces
64
Which Dietary Factors Most Influence A
Person’s Risk…
• Fluids and cancer
– Men who drink about 10 cups of fluid a
day have been reported to develop
substantially less bladder cancer than
those drinking only about half this
amount
– A greater fluid intake dilutes the
carcinogens that naturally form in urine
and causes more frequent urination
– Plain water seems most beneficial
65
Which Dietary Factors Most Influence A
Person’s Risk…
•
Folate and Other Vitamins
–
Folate deficiency seems to make cancers
of the cervix and colon more likely
•
•
Up to 10% of the U.S. population, and a much larger
percentage of people with low incomes, consume a
diet low enough in folate to cause breaks in DNA that
make cancer likely to develop
Vitamin A
–
–
Regulates aspects of cell division and
communication that go awry in cancer
Helps to maintain the immune system
•
Immune system cells can often identify cancerous cells
and destroy them before cancer can develop
66
Which Dietary Factors Most Influence A
Person’s Risk…
• Vitamin D and exposure to sunshine
have long been suggested as
protective against cancers
– Other than skin cancer
– The relationship is not clearly defined
• Calcium and Other Minerals
– Laboratory evidence suggests that a
high-calcium diet may help to prevent
colon cancer
• Supplemental calcium seems to suppress
changes in the lining of the colon associated
with the onset of cancerous changes
67
Which Dietary Factors Most Influence A
Person’s Risk…
• A recent review revealed that the
majority of studies since 1990
confirm an association between colon
cancer and both increased dietary
iron intake and high body iron stores
• Iron is a powerful oxidizing substance
-Oxidation may damage cell DNA to initiate
cancer
-Whether iron increases a person’s risk for
colon cancer may depend on inherited
tendency to store too much iron, degree
of iron intake
68
Foods with phytochemicals and cancer
•
Whole foods and whole diets composed of
them, not single nutrients, may be most
influential on cancer development
-The phytochemicals in some fruits and
vegetables are thought to be anticarcinogens
-Some phytochemicals for fighting cancer include
lycopene (tomato based foods and watermelon)
and ellagic acid (blueberries)
-Phytochemicals in foods interfere with cancer
cell progression at all stages of development
•
Phytochemical rich foods called functional foods
69
Foods with phytochemicals and cancer
-A low intake of fruits and vegetables
may leave cells unprotected against
DNA damage in the initiation of many
cancers
-Infrequent use of cruciferous
vegetables - broccoli, brussels
sprouts, cabbage, cauliflower, turnips,
and the like - is common in colon and
breast cancer cases
-Incidence of stomach cancer correlates
with too few vegetables in the diet
• In one study, with vegetables in general
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Controversy: The Obesity Epidemic How Can We
Gain Control?
• 97 million obese
people
– Are at increased risk
of serious illnesses
associated with
obesity (heart
disease, arthritis,
cancer)
• $60 billion spent on
obesity-related
health care
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The Obesity Epidemic - How Can We Gain
Control?
• Why Has Our Society become Obesity-Prone?
– Today, many people regularly overeat large
portions of inexpensive high-calorie foods500 more calories than in 1970
– Changes in how leisure time spent
– Limited physical activity
– Lends itself to weight gain and poor sleep
– May worsen with high calorie or caffeine
drinks/foods to promote more energy
– and other inappropriate supplements,
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alcohol, tobacco, or other drugs
The Obesity Epidemic - How Can We
Gain Control?
• Changing Physical Activity
– Technological advances have relieved
people of many physical labor saving
activities that would have expended
calories in the past
• Changing Home Life
– Changes in the family structure (more
time in work force, less meals at home)
– The diet has changed more over the past
40 years than in any other comparable
period of human existence
73
The Obesity Epidemic - How Can We Gain
Control?
• Food Advertising
– The food industry spends more than $33
billion each year on advertising which often
promotes less healthy options
• The “Buy More” Strategy
– Appeals to economic sense-”supersizing”
– Larger food packages at retail level may
prompt cooking larger portions
• Portion sizes and obesity rates have increased
proportionately over the years
• Marketing to Children-billions spent to market
high calorie snack foods and beverages
74
The Obesity Epidemic - How Can We
Gain Control?
• Nutrition Education
– Part of the blame for unheeded dietary
advice is placed on inadequate education in
today’s schools
– A law passed in 1977 mandates that federal
funds be supplied to states for training
teachers to teach nutrition, but sufficient
funds not always made available
– Some schools have set an example for
healthier eating by removing soda pop
machines
– Some school districts have decreased
physical education requirements
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The Obesity Epidemic - How Can We Gain
Control?
• Consumers can choose to live a lifestyle that
can promote health and decrease obesity
– Turn off the television and take up a physically
active recreation
– Park farther away than usual and walk through the
parking lot
– Seek out and use stairways instead of elevators
– Obtain an inexpensive pedometer and vow to walk
10,000 steps each day
– Watch portion sizes, eat out less often
– Save enticing fatty and sugary fast foods and
snacks for special occasions
– Teach the children in our lives to think differently
about food
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