1. Diet and Health Guidelines to Lower
Risk of Cancer
Presented by
Janice Hermann, PhD, RD/LD
OCES Adult and Older Adult Nutrition Specialist
Oklahoma Cooperative Extension Service
02/22/14
2. Cancer
Cancer second leading cause of death in the
United States
Cancer not a single disorder
Many types
Different characteristics
Occur in different body locations
Take different courses
Require different treatments
3. Cancer Development
Genes work together to regulate cell division
and ensure new cells are replicas of parent
cells
Process allows:
Body to grow
Replace dead cells
Repair damaged cells
4. Cancer Development
Cancer develops from mutations in genes
regulating cell division
Mutations inhibit genes that ordinarily monitor
and correct errors
Affected cells lose ability to stop cell division
Result is an abnormal mass of cells
5. Cancer Development
An abnormal mass of cells is called a tumor
Benign
Tumors that stop growing without intervention or can
be surgically removed
Most often pose no threat to health
Malignant
Tumors that multiply out of control
Threaten surrounding tissues and health
6. How Cancer Develops
As a malignant tumor grows, blood vessels
form to supply the tumor with nutrients
Eventually, the tumor invades more and
more healthy tissue and may metastasize
Malignant cancers are described by:
Location
Size
Extent of growth
If spread to surrounding lymph nodes
If spread to distant sites in the body
9. Cancer Development
Genetic factors
All cancers have a genetic component in that a
mutation causes abnormal cell growth
Some cancers have a genetically inherited
component as well
Example: someone with a family history of color cancer
has a greater risk of developing colon cancer than
someone without a genetic predisposition; however, this
does not mean that they will develop colon cancer
10. Cancer Development
Immune factors
A healthy immune system recognizes foreign cells
and destroys them
Theorized an ineffective immune system may not
recognize tumor cells as foreign, thus allowing
unchecked cell growth
Aging affects immune function, and incidence of cancer
increases with age
Diseases that weaken the immune system can increase
cancer risk
12. Cancer Development
Physical Activity
Lack of physical activity may play a role in the
development of some types of 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 by other mechanisms
unrelated to body weight
13. Cancer Development
Dietary Factors
Estimates are 1/3 of cancers attributed to
nutrition
Cancer Initiators
Some dietary factors may initiate cancer development
Cancer Promoters
Other dietary factors may promote cancer development
once it has started
Protective Factors
Still other dietary factors may protect against cancer
development
14. Diet and Cancer Studies
Epidemiological studies try to identify relationships
between the diet of population groups and
incidence of specific cancers
Diet complexity makes identifying relationships
difficult
Thousands of chemicals in a diet
Diets contain initiators, promoters and protective factors
Changing one factor in the diet may change others, making
identifying individual factors difficult
Many cancers have a long latency period, thus diet at
initiation or promotion may not be the same as at
diagnosis
15. Dietary Factors: Cancer Initiators
Pesticides
Some pesticides may be carcinogenic at extremely
high doses, however, they are safe at the levels
permitted on fruits and vegetables
The benefits of eating fruits and vegetables are
far greater than any potential risk
Food additives
Those approved for use in foods are not
carcinogenic
16. Dietary Factors: Cancer Initiators
Alcohol
Alcohol associated with increased risk of mouth,
esophageal and breast cancer
Mouth and esophageal cancer are especially increased if
alcohol is combined with smoking
17. Dietary Factors: Cancer Initiators
Alcohol
If alcohol intake causes liver cirrhosis, there is an
increased risk of liver cancer
Malnutrition associated with alcoholism is also
likely to be important in the increased risk for
certain cancers
Thus, potential benefits of moderate alcohol
intake for cardiovascular disease must be
weighed against potential risks
18. Dietary Factors: Cancer Initiators
Food preparation methods
Cooking meat, poultry, and fish at high
temperatures and smoking meat causes
carcinogens to form on food surfaces which have
been related to colon, breast and stomach cancer
High heat cooking methods such as grilling, broiling, and
barbecuing
Healthier cooking methods include roasting,
broiling, poaching, steaming, stewing, braising
and microwaving
Fruits and vegetables appear to provide a
protective effect
19. Dietary Factors: Cancer Initiators
Food preparation methods
Large amounts of salt-cured and salt-pickled foods
have been related to stomach, colon and bladder
cancers
Sodium and potassium nitrates used in salting, pickling,
and curing processes
Nitrates can be converted into nitrite, which can form
potential carcinogens nitrosamines
Diets with high amounts of fruits and vegetables
contain vitamin C and phytochemicals can retard
conversion of nitrites to nitrosamines
20. Dietary Factors: Cancer Promoters
High fat diets
High dietary total fat and saturated fat may be
related to increased risk of breast, colon,
endometrial and prostate cancer
Omega-3 fatty acids however, may be protective
Thus same dietary fat advice applies to cancer
protection as to heart disease
Reduce total fat and saturated fat
Increase omega-3 fatty acids
21. Dietary Factors: Cancer Promoters
High fat diets
May increase cancer risk by increasing:
Obesity
Bile acid production
Estrogen levels
Because fat is calorie dense it is difficult to
distinguish between the effects of high dietary fat,
and total calories
22. Dietary Factors: Cancer Promoters
High calorie intake
In most epidemiologic studies, a positive
association has been seen with high calorie intake
and promotion of breast, colon and endometrial
cancer
Increased risk may be due to:
Excess calories themselves
Weight gain due to excess calories
High fat intake that often supplies excess calories
23. Dietary Factors: Cancer Promoters
Obesity may increase risk of colon,
endometrial and breast cancer
Increased risk may be due to:
Extra weight
Adipose tissue production of estrogen
Extra calories
High fat intake that often supplies excess calories and
contributes to weight gain
Protective effect of physical activity related to
breast and colon cancer may be due in part to
helping to control obesity
24. Dietary Factors: Cancer Promoters
Protein
Excessive muscle meat sources of protein have
been related to increased risk of colon and
prostate cancer
Not know if increased risk due to:
Protein level
Fat content
Fat type
Increased calories from fat
Other factor such as being low in fiber, antioxidants and
phytochemicals
Further research needed
25. Dietary Factors: Cancer Promoters
Protein
In general tumor development is:
Suppressed by diets that contain protein below that
required for optimal growth
Enhanced by protein levels two to three times the
amount required
26. Dietary Factors: Protective Factors
Fruits, vegetables, whole grains and legumes
Epidemiological studies show a link between diets
with plenty of fruits, vegetables, whole grains and
legumes and reduced incidence oral cavity,
esophagus, stomach, colon and lung cancer
Compounds in these foods that may help lower
cancer risk:
Dietary fiber
Vitamin C
Vitamin E
Phytochemicals
Low fat
27. Dietary Factors: Protective Factors
Fruits, vegetables whole grains and legumes:
Fiber
Fiber-rich diets may protect against colon cancer
In the intestine bile can be converted into potential
cancer causing substances. Soluble fibers can bind bile
acids and increase their excretion
Insoluble fibers absorb water making a larger, softer stool
which can dilute potential cancer causing substances
A larger, softer stool moves through intestine faster so
colon exposed to cancer causing substance for less time
Foods high in fiber are typically lower in fat, which may
also help protect against colon cancer by reducing bile
acid production
28. Dietary Factors: Protective Factors
Fruits, vegetables, whole grains and legumes:
Antioxidants
Fruits, vegetables, whole grains and legumes also
contain antioxidant nutrients that may protect
against cancer
Antioxidants stop free radical oxidation which may help
to prevent cell and tissue damage that can promote
cancer
Possible these nutrients have many other effects in the
body which lower cancer risk
29. Dietary Factors: Protective Factors
Fruits, vegetables, whole grains and legumes:
Phytochemicals
Fruits, vegetables, whole grains and legumes also
contain phytochemicals that may protect against
cancer
Some function antioxidants, protecting against harmful
cell damage from oxidation
Others lower cancer risk in different ways such as
activating enzymes that destroy carcinogens
30. Dietary Factors: Protective Factors
Fruits, vegetables, whole grains, and legumes
Because it is not known which specific substances
in fruits, vegetables, whole grains and legumes
help to lower cancer and whether it is the
substances themselves or their presence in food,
the best recommendation is to eat a variety of
these foods.
Best to get these nutrients from foods not
supplements.
31. Dietary Factors: Protective Factors
Calcium
Calcium may have a role in lowering colon cancer;
however, more research is needed
In the meantime, adequate calcium is known to
be important for growth and bone development
32. Cancer Development
Evidence suggests millions of cases of cancer
could be prevented by changes in:
Diet
Weight control
Physical activity
Smoking
33. Consequences of Cancer
Nonspecific effects of cancer include:
Anorexia and reduced food intake
Metabolic alterations
Tissue wasting and weight loss
Anorexia, tissue wasting, weight loss and
fatigue typify cancer cachexia
Occurs in as many as 80% of people with cancer
34. Consequences of Cancer
Anorexia and Reduced Food Intake
Major contributors to wasting
With cancer body may not be able to respond to
reduced nutrient intake and nutrient stores are
rapidly depleted
Without adequate energy and nutrients, the body is
poorly equipped to:
Maintain immune defenses
Support organ function
Absorb nutrients
Repair damaged tissues
35. Consequences of Cancer
Anorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food
intake:
Chronic nausea and early satiety
People with cancer frequently experience nausea and a premature
feeling of fullness after eating small amounts of food
Fatigue
People with cancer often tire easily and lack the energy to prepare
and eat meals
If cachexia develops, these tasks become even more difficult to
handle
36. Consequences of Cancer
Anorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food
intake:
Pain
People in pain may have little interest in eating, particularly if
eating makes pain worse
Mental stress
A cancer diagnosis can cause distress, anxiety, and depression, all
of which may reduce appetite
Facing and undergoing cancer treatments causes additional
psychological stress
37. Consequences of Cancer
Anorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food
intake (cont.):
Effects of cancer therapies
Therapies for cancer (including medications, chemotherapy
radiation therapy, surgery, and bone marrow transplants) can
affect food intake by causing nausea, vomiting, altered taste
perceptions, food aversions, inflammation of the mouth and
esophagus, dry mouth, mouth sores, difficulty swallowing,
intestinal cramping, diarrhea, and constipation
38. Consequences of Cancer
Anorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food
intake (cont.):
Obstructions
A tumor may partially or completely obstruct a portion of the GI
tract, causing complications such as nausea and vomiting, early
satiety, delayed gastric emptying, and bacterial overgrowth
Some patients with obstructions are unable to tolerate oral diets
39. Consequences of Cancer
Metabolic Alterations
Metabolic changes can also exacerbate wasting
Increased protein turnover, but reduced muscle protein
synthesis
Increased gluconeogenesis, further straining supply of
body proteins
Increased triglyceride breakdown, but decreased fat
synthesis
Many develop insulin resistance
Metabolic alterations help explain why people
with cancer fail to regain lean body mass or
maintain healthy body weights even when
receiving adequate energy and nutrients
40. Consequences of Cancer
Tissue Wasting
Weight loss often evident at time cancer diagnosed
Factors contributing to wasting
Anorexia and reduced food intake
Metabolic alterations
Cytokines released by both tumor and immune cells
induces a hypermetabolic, catabolic state
Diversion of nutrients to support tumor growth result in
lower energy and nutrients available to healthy tissues
Severe tissue wasting, often seen in the later stages
of cancer, may be ultimate cause of death
41. Cancer Treatments
Primary medical treatments for cancer are:
Surgery
Chemotherapy
Radiation Therapy
Aim is to remove cancer cells, prevent
further tumor growth, and alleviate
symptoms
Medical treatments can effect nutritional
status
42. Cancer Treatments
Surgery
Performed to remove tumors
Can affect nutritional status
Acute metabolic stress caused by surgery raises protein
and energy needs and can exacerbate wasting
Surgery may also contribute to pain, fatigue, anorexia
and reduced food intake
Blood loss further contribute to nutrient losses
43. Cancer Treatments
Chemotherapy
Used to inhibit tumor growth
Interfere or prevent cell division
Affect rapidly growing cancer cells
Unfortunately, most of these drugs can effect
normal cells (especially rapidly dividing cells, such
as those in the GI tract, skin and bone marrow)
and can effect nutritional status due to:
Anorexia
Nausea
Malabsorption
Diarrhea
44. Cancer Treatments
Radiation Therapy
Bombarding cancer cells with radiation induces
formation of reactive oxygen species, such as
superoxide and hydroxyl radicals, which can
damage cellular DNA and cause cell death
Radiation can effect normal cells and can effect
nutritional status
Radiation to head and neck may damage salivary glands
and taste buds, causing dry mouth and altered taste
Radiation to lower abdomen can cause radiation
enteritis, inflammation of the small intestine, causing
nausea, vomiting, diarrhea, and malabsorption
45. Cancer Treatments
Bone Marrow Transplants
Replace bone marrow destroyed by
chemotherapy or radiation
Primary treatment for leukemia
Can substantially effect nutritional status
After bone marrow is destroyed, immune function is
suppressed, increasing the risk of foodborne illness
Effects of transplant include anorexia, dry mouth,
inflamed mucous membranes, altered taste, and
diarrhea
Patients often unable to consume adequate food and
may require nutritional support
46. Cancer Treatments
Medications to combat anorexia and wasting
Medications sometimes prescribed to
stimulate the appetite and promote weight
gain
47. Cancer Treatments
Alternative therapies
60 to 80% of cancer patients combine
complementary and alternative medicine (CAM)
approaches with standard treatment
Many people do not discuss their use of
complementary and alternative medicine
approaches with their physicians
48. Cancer Treatments
Alternative therapies
Dietary supplements and herbal remedies among
most frequently used CAM
Many supplements can be used without risk;
however, others may have adverse effects or
interfere with conventional treatments
St. John’s wort can reduce effectiveness of some
anticancer drugs
Antioxidant supplementation may interfere with
chemotherapy and radiation treatment
49. Nutritional Therapy
Objectives of medical nutrition therapy are to:
Minimize tissue wasting and weight loss
Protein and energy needs are considerable to prevent
tissue wasting and weight loss.
Correct nutritional deficiencies
Help people maintain their strength and immune
function
Provide a diet that can be tolerated and enjoyed
despite the complications of illness
50. Nutrition Therapy
Nutrition therapy depends on the type and
severity of cancer, side effects of treatment
and patient’s nutritional status
In addition, factors may interfere with eating
51. Nutrition Therapy
Enteral (tube) and parenteral (intravenous) nutrition
support
Tube feedings and intravenous nutrition not routinely
recommended for adequately nourished or mildly
malnourished people with cancer who are able to eat
However, these approaches help to maintain nutrition
status when anorexia persists or when a patient is severely
malnourished and is about to undergo aggressive cancer
therapy
Each case is decided individually
52. Nutrition Therapy
Nutrition support for bone marrow transplants
People undergoing a bone marrow transplant routinely
receive total parenteral nutrition (TPN) before and after
the transplant because the GI tract is severely
compromised by the preparatory procedure
When GI function return, the patient begins to receive
foods orally along with TPN, whenever possible
As oral intake improves, TPN is gradually tapered off
Notas do Editor
Cancer is the second leading cause of death in the United States.
Cancer not a single disorder. There are:
Many types
Different characteristics
Occur in different body locations
Take different courses
Require different treatments
Genes in the body work together to regulate cell division and ensure new cells are replicas of parent cells.
This process allows:
Body to grow
Replace dead cells
Repair damaged cells
Cancer develops from mutations in genes regulating cell division resulting in mutations that inhibit genes that ordinarily monitor and correct errors. Affected cells lose ability to stop cell division. This results in an abnormal mass of cells.
An abnormal mass of cells is called a tumor. A benign tumor is one that stop growing without intervention or can be surgically removed. Most benign tumors pose no threat to health. A malignant tumor is one that multiplies out of control. A malignant tumor can threaten surrounding tissues and health.
As a malignant tumor grows, blood vessels form to supply the tumor with nutrients. Eventually, the tumor invades more and more healthy tissue and may metastasize (spread to other areas of the body).
Malignant cancers are described by:
Location
Size
Extent of growth
If spread to surrounding lymph nodes
If spread to distant sites in the body
There are many factors that can influence cancer development:
Genetic Factors
Immune Factors
Environmental Factors
Physical Activity
Dietary Factors. Dietary factors may initiate, promote or inhibit the growth of cancer cells.
Genetic factors
All cancers have a genetic component in that a mutation causes abnormal cell growth. Some cancers have a genetically inherited component as well. For example, someone with a family history of color cancer has a greater risk of developing colon cancer than someone without a genetic predisposition; however, this does not mean that they will develop colon cancer.
Immune factors
A healthy immune system recognizes foreign cells and destroys them. Theorized an ineffective immune system may not recognize tumor cells as foreign, thus allowing unchecked cell growth.
Aging affects immune function, and incidence of cancer increases with age. Diseases that weaken the immune system can increase cancer risk.
Environmental Factors
Some environmental factors are known to cause cancer:
Exposure to radiation and sunlight
Water and air pollution
Smoking
Physical Activity
Lack of physical activity may play a role in the development of some types of cancer.
For example 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 by other mechanisms unrelated to body weight.
Dietary Factors
Estimates are 1/3 of cancers attributed to nutrition. Dietary factors may initiate, promote or inhibit the growth of cancer cells. Different dietary factors affects different types of cancer.
Cancer Initiators. Some dietary factors may initiate cancer development
Cancer Promoters. Other dietary factors may promote cancer development once it has started
Protective Factors. Still other dietary factors may protect against cancer development
Diet and Cancer Studies
Epidemiological studies try to identify relationships between the diet of population groups and incidence of specific cancers. Diet complexity makes identifying relationships difficult because:
Thousands of chemicals in a diet
Diets contain initiators, promoters and protective factors
Changing one factor in the diet may change others, making identifying individual factors difficult
Many cancers have a long latency period, thus diet at initiation or promotion may not be the same as at diagnosis
Dietary Factors: Cancer Initiators
Pesticides
Some pesticides may be carcinogenic at extremely high doses, however, they are safe at the levels permitted on fruits and vegetables. The benefits of eating fruits and vegetables are far greater than any potential risk.
Food additives
Those approved by the FDA for use in foods are not carcinogenic.
Dietary Factors: Cancer Initiators
Alcohol
Alcohol is associated with increased risk of mouth, esophageal and breast cancer.
Mouth and esophageal cancer are especially increased if alcohol is combined with smoking.
The relationship between alcohol and breast cancer may be due to alcohol-induced increases of estrogen levels, reduction of folic acid levels or direct effect of alcohol or its metabolites on breast tissue.
Dietary Factors: Cancer Initiators
Alcohol
If alcohol intake causes liver cirrhosis, there is an increased risk of liver cancer.
Malnutrition associated with alcoholism is also likely to be important in the increased risk for certain cancers.
Thus, potential benefits of moderate alcohol intake for cardiovascular disease must be weighed against potential risks.
Dietary Factors: Cancer Initiators
Food Preparation Methods
Cooking meat, poultry, and fish at high temperatures and smoking meat causes carcinogens to form on food surfaces which have been related to colon, breast and stomach cancer.
High heat cooking methods such as grilling, broiling, and barbecuing. Polycyclic aromatic hydrocarbons and hetrocyclic amines are formed when high-heat cooking methods such as grilling, broiling, barbecuing, and smoking meats are used. These substances are formed during combustion of carbon fuel and pyrolysis of protein.
Healthier cooking methods include roasting, broiling, poaching, steaming, stewing, braising and microwaving.
Fruits and vegetables appear to provide a protective effect against this risk.
Dietary Factors: Cancer Initiators
Food Preparation Methods
Large amounts of salt-cured and salt-pickled foods have been related to stomach, colon and bladder cancers.
Sodium and potassium nitrates used in salting, pickling, and curing processes. Nitrates can be converted into nitrite, which can interact with dietary compounds, such as amines and amides, to produce nitrosamines and nitrosamides, potential carcinogens.
The risk is primarily for individuals who consume excessive amounts of these types of foods, and is not a major issue for most individuals.
Diets with high amounts of fruits and vegetables contain vitamin C and phytochemicals can retard conversion of nitrites to nitrosamines.
Dietary Factors: Cancer Promoters
High Fat Diet
High dietary total fat and saturated fat may be related to increased risk of breast, colon, endometrial and prostate cancer. However, omega-3 fatty acids however, may be protective.
Thus same dietary fat advice applies to cancer protection as to heart disease:
Reduce total fat and saturated fat
Increase omega-3 fatty acids
Dietary Factors: Cancer Promoters
High Fat Diet
High fats diets may increase cancer risk through increasing obesity, bile acid production, and estrogen levels. Because fat is calorie dense it is difficult to distinguish between the effects of dietary fat and total calories.
Dietary Factors: Cancer Promoters
High Calorie Intake
In most epidemiologic studies, a positive association has been seen with high calorie intake and promotion of breast, colon and endometrial cancer.
The increase in cancer risk may be due to the excess calories themselves, weight gain due to excess calories, or high fat intake that often supplies excess calories and contributes to weight gain.
Dietary Factors: Cancer Promoters
Obesity
Obesity may increase risk of colon, endometrial and breast cancer. The increased risk may be due to:
Extra weight
Adipose tissue production of estrogen
Extra calories
High fat intake that often supplies excess calories and contributes to weight gain
Protective effect of physical activity related to breast and colon cancer may be due in part to helping to control obesity.
Dietary Factors: Cancer Promoters
Protein
Excessive muscle meat sources of protein have been related to increased risk of colon and prostate cancer. Not know if increased risk due to:
Protein level
Fat content
Fat type
Increased calories from fat
Other factor such as being low in fiber, antioxidants and phytochemicals
The amount of muscle meat protein recommended by USDA Daily Food Plan is not excessive.
Further research needed
Dietary Factors: Cancer Promoters
Protein
In general tumor development is:
Suppressed by diets that contain protein below that required for optimal growth
Enhanced by protein levels two to three times the amount required
Dietary Factors: Protective Factors
Fruits, vegetables whole grains and legumes
Epidemiological studies show a link between diets with plenty of fruits, vegetables, whole grains and legumes and reduced incidence oral cavity, esophagus, stomach, colon and lung cancer.
These foods contain essential nutrients and other important substances that may help lower the risk of cancer, as well as being low in fat. Some of the compounds in these foods that may help lower cancer risk:
Dietary fiber
Vitamin C
Vitamin E
Phytochemicals
Low fat
Dietary Factors: Protective Factors
Fruits, vegetables whole grains and legumes: Fiber
Fiber-rich diets may protect against colon cancer. There are two types of fiber, water-soluble fiber and water-insoluble fiber. Both insoluble and soluble fibers may protect against colorectal cancer.
Bile acids are released into the intestine to help with fat digestion. In the intestine bile can be converted into potential cancer causing substances. Soluble fibers can bind bile acids and increase their excretion.
Insoluble fibers absorb water making a larger, softer stool which can dilute potential cancer causing substances. A larger, softer stool moves through intestine faster so colon exposed to cancer causing substance for less time.
Foods high in fiber are typically lower in fat, which may also help protect against colon cancer by reducing bile acid production.
In addition high fiber foods including fruits, vegetables, whole grains and legumes provide many other nutrients that can lower risk including antioxidants; selenium, Vitamin C, vitamin E and beta-carotene and phyotochemicals. This is another important reason to increase fiber from food sources, rather than supplements, because food sources provide both types of fiber.
Dietary Factors: Protective Factors
Fruits, vegetables whole grains and legumes: Antioxidants
Fruits, vegetables, whole grains and legumes also contain antioxidant nutrients; vitamin C, vitamin E and selenium that may protect against cancer.
Antioxidants stop free radical oxidation which may help to prevent cell and tissue damage that can promote cancer. It’s also possible these nutrients have many other effects in the body which lower cancer risk.
Dietary Factors: Protective Factors
Fruits, vegetables whole grains and legumes: Phytochemicals
Fruits, vegetables, whole grains and legumes also contain phytochemicals that may protect against cancer.
Some phytochemcials function as antioxidants, protecting against harmful cell damage from oxidation. Others lower cancer risk in different ways such as activating enzymes that destroy carcinogens.
Dietary Factors: Protective Factors
Fruits, vegetables whole grains and legumes
Because it is unclear which specific substances in fruits, vegetables whole grains and legumes help to lower cancer risk, at the present time the best recommendation is to eat a variety of these foods.
Even though these nutrients can be purchased as supplements, the best way to get them is through food sources. It is not known whether these nutrients by themselves, or as they occur in food, or other nutrients in these foods is the beneficial factor. In addition to these nutrients fruits, vegetables, whole grains, and legumes contain hundreds of different compounds called phytochemicals. Research into the role of phytochemicals in reducing cancer risk is just beginning.
Dietary Factors: Protective Factors
Calcium
Calcium may have a role in lowering colorectal cancer; however it is too early to be sure. In the meantime, it is known that adequate calcium throughout the lifespan is important for growth and bone development.
There is a relationship between diet and cancer. In fact one-third of cancer deaths are estimated to be attributed to nutrition and other lifestyle factors, and another third is related to cigarette smoking and tobacco use.
Evidence suggests millions of cases of cancer could be prevented by changes in:
Diet
Weight control
Physical activity
Smoking
Consequences of Cancer
Nonspecific effects of cancer include:
Anorexia and reduced food intake
Metabolic alterations
Tissue wasting and weight loss
Loss of appetite, tissue wasting, weight loss and fatigue typify cancer cachexia, which occurs in as many as 80% of people with cancer.
Consequences of Cancer
Anorexia and Reduced Food Intake
Anorexia and reduced food intake are major contributors to wasting.
With cancer the body may not be able to respond to reduced nutrient intake and nutrient stores are rapidly depleted. Without adequate energy and nutrients, the body is poorly equipped to:
Maintain immune defenses
Support organ function
Absorb nutrients
Repair damaged tissues
Consequences of Cancer
Some factors that may contribute to anorexia and reduced food intake include:
Chronic nausea and early satiety. People with cancer frequently experience nausea and a premature feeling of fullness after eating small amounts of food.
Fatigue. People with cancer often tire easily and lack the energy to prepare and eat meals. If cachexia develops, these tasks become even more difficult to handle.
Consequences of Cancer
Some factors that may contribute to anorexia and reduced food intake include (cont.):
Pain. People in pain may have little interest in eating, particularly if eating makes pain worse.
Mental stress. A cancer diagnosis can cause distress, anxiety, and depression, all of which may reduce appetite. Facing and undergoing cancer treatments causes additional psychological stress.
Consequences of Cancer
Some factors that may contribute to anorexia and reduced food intake include (cont.):
Effects of cancer therapies. Therapies for cancer (including medications, chemotherapy radiation therapy, surgery, and bone marrow transplants) can affect food intake by causing nausea, vomiting, altered taste perceptions, food aversions, inflammation of the mouth and esophagus, dry mouth, mouth sores, difficulty swallowing, intestinal cramping
Consequences of Cancer
Some factors that may contribute to anorexia and reduced food intake include (cont.):
Obstructions. A tumor may partially or completely obstruct a portion of the GI tract, causing complications such as nausea and vomiting, early satiety, delayed gastric emptying, and bacterial overgrowth. Some patients with obstructions are unable to tolerate oral diets.
Consequences of Cancer
Metabolic Alterations
Metabolic changes can also exacerbate wasting. Examples of metabolic changes with cancer include:
Increased protein turnover, but reduced muscle protein synthesis
Increased gluconeogenesis, further straining supply of body proteins
Increased triglyceride breakdown, but decreased fat synthesis
Many develop insulin resistance
Metabolic alterations help explain why people with cancer fail to regain lean body mass or maintain healthy body weights even when receiving adequate energy and nutrients.
Consequences of Cancer
Tissue Wasting
Weight loss often evident at time cancer diagnosed.
Factors contributing to wasting:
Anorexia and reduced food intake
Metabolic alterations
Cytokines released by both tumor and immune cells induces a hypermetabolic, catabolic state
Diversion of nutrients to support tumor growth result in lower energy and nutrients available to healthy tissues
Severe tissue wasting, often seen in the later stages of cancer, may be ultimate cause of death.
Cancer Treatments
Primary medical treatments for cancer are:
Surgery
Chemotherapy
Radiation Therapy
The aim of treatment is to remove cancer cells, prevent further tumor growth, and alleviate symptoms.
However, medical treatments can effect nutritional status.
Cancer Treatments
Surgery
Surgery is often performed to remove tumors.
Surgery can affect nutritional status:
Acute metabolic stress caused by surgery raises protein and energy needs and can exacerbate wasting.
Surgery may also contribute to pain, fatigue, anorexia and reduced food intake.
Blood loss further contribute to nutrient losses.
Cancer Treatments
Chemotherapy
Used to inhibit tumor growth by interfering or preventing cell division. These treatments affect rapidly growing cancer cells.
Unfortunately, most of these drugs can effect normal cells (especially rapidly dividing cells, such as those in the GI tract, skin and bone marrow) and can effect nutritional status due to:
Anorexia
Malabsorption
Diarrhea
Cancer Treatments
Radiation Therapy
Bombarding cancer cells with radiation induces formation of reactive oxygen species, such as superoxide and hydroxyl radicals, which can damage cellular DNA and cause cell death.
Radiation can effect normal cells and can effect nutritional status:
Radiation to head and neck may damage salivary glands and taste buds, causing dry mouth and altered taste.
Radiation to lower abdomen can cause radiation enteritis, inflammation of the small intestine, causing nausea, vomiting, diarrhea, and malabsorption.
Cancer Treatments
Bone Marrow Transplants
Replace bone marrow destroyed by chemotherapy or radiation is a primary treatment for leukemia.
Bone marrow transplants can substantially effect nutritional status:
After bone marrow is destroyed, immune function is suppressed, increasing the risk of foodborne illness
Effects of transplant include anorexia, dry mouth, inflamed mucous membranes, altered taste, and diarrhea
Patients often unable to consume adequate food and may require nutritional support
Cancer Treatments
There are medications to combat anorexia and wasting. Medications sometimes prescribed to stimulate the appetite and promote weight gain.
Cancer Treatments
Alternative Therapies
60 to 80% of cancer patients combine complementary and alternative medicine (CAM) approaches with standard treatment.
Many people do not discuss their use of complementary and alternative medicine approaches with their physicians
Cancer Treatments
Alternative Therapies
Dietary supplements and herbal remedies among most frequently used complementary and alternative medicine (CAM) approaches.
Many supplements can be used without risk; however, others may have adverse effects or interfere with conventional treatments:
St. John’s wort can reduce effectiveness of some anticancer drugs
Antioxidant supplementation may interfere with chemotherapy and radiation treatment
Nutrition Therapy
Objectives of medical nutrition therapy are to:
Minimize tissue wasting and weight loss
Protein and energy needs are considerable to prevent tissue wasting and weight loss.
Correct nutritional deficiencies
Help people maintain their strength and immune function
Provide a diet that can be tolerated and enjoyed despite the complications of illness
Nutrition Therapy
Nutrition therapy depends on the type and severity of cancer, side effects of treatment and patient’s nutritional status. In addition, factors may interfere with eating.
Nutrition Therapy
Enteral (tube) and parenteral (intravenous) nutrition support
Tube feedings and intravenous nutrition not routinely recommended for adequately nourished or mildly malnourished people with cancer who are able to eat.
However, these approaches help to maintain nutrition status when anorexia persists or when a patient is severely malnourished and is about to undergo aggressive cancer therapy.
Each case needs to be decided individually.
Nutrition Therapy
Nutrition support for bone marrow transplants
People undergoing a bone marrow transplant routinely receive total parenteral nutrition (TPN) before and after the transplant because the GI tract is severely compromised by the preparatory procedure.
When GI function return, the patient begins to receive foods orally along with TPN, whenever possible. As oral intake improves, TPN is gradually tapered off.